Current research on empathy for pain emphasizes the overlap in the neural response between the first-hand experience of pain and its perception in others. However, recent studies suggest that the perception of the pain of others may reflect the processing of a threat or negative arousal rather than an automatic pro-social response. It can thus be suggested that pain processing of other-related, but not self-related, information could imply danger rather than empathy, due to the possible threat represented in the expressions of others (especially if associated with pain stimuli). To test this hypothesis, two experiments considering subliminal stimuli were designed. In Experiment 1, neutral and semantic pain expressions previously primed with own or other faces were presented to participants. When other-face priming was used, only the detection of semantic pain expressions was facilitated. In Experiment 2, pictures with pain and neutral scenarios previously used in ERP and fMRI research were used in a categorization task. Those pictures were primed with own or other faces following the same procedure as in Experiment 1 while ERPs were recorded. Early (N1) and late (P3) cortical responses between pain and no-pain were modulated only in the other-face priming condition. These results support the threat value of pain hypothesis and suggest the necessity for the inclusion of own- versus other-related information in future empathy for pain research.

Although evidence is accumulating that prenatal testosterone (T) compromises reproductive function in the female, the effects of excess T in utero on the postnatal development of male reproductive function has not been studied. The aim of this study was to assess the influence of prenatal T excess on age-related changes in pituitary and gonadal responsiveness to GnRH in the male sheep. We used the GnRH agonist, leuprolide (10 microg/kg), as a pharmacologic challenge at 5, 10, 20 and 30 weeks of age. These time points correspond to early and late juvenile periods and the prepubertal and postpubertal periods of sexual development, respectively. LH and T were measured in blood samples collected before and after GnRH agonist administration. The area under the response curve (AUC) of LH increased progressively in both controls and prenatal T-treated males from 5 to 20 weeks of age (P<0.01). The LH responses in prenatal T-treated males were lower at 20 and 30 weeks of age compared to controls (P<0.05). AUC-T increased progressively in control males from 5 through 30 weeks of age and prenatal T-treated males from 5 to 20 weeks of age. The T response in prenatal T-treated males was higher at 20 weeks compared to controls of same age but similar to controls and prenatal T-treated males at 30 weeks of age (P <0.05). Our findings suggest that prenatal T treatment advances the developmental trajectory of gonadal responsiveness to GnRH in male offspring.

LH and FSH secretions depend on the pulsatile secretion of GnRH from the hypothalamus. However, the grade of dependency as well as the relationship between pulses of GnRH and pulses of FSH secretion is less clear. Experiments in monkeys have shown that high GnRH pulse frequency favors LH secretion while low frequency of GnRH pulses preferentially stimulates the FSH secretion. The objective of the present work was to recognize the dependence of GnRH on the FSH secretion in prepubertal female sheep. A GnRH agonist analogue in slow release microcapsule preparation was used (Trp6-GnRH, (Decapeptyl(R))) whose blocking effect on the LH release has been previously demonstrated. The analogue was injected intramuscularly every 4 weeks beginning at 20 weeks of age three times in five Suffolk ewe lambs. Another group of five lambs received the vehicle of Decapeptyl. Studies of FSH pulsatility were carried out at 20 (before the analogue agonist administration), 26 and 30 weeks of age. The CLUSTER program was used to identify characteristics of FSH secretion: transversal mean (ng/ml/5h), frequency Of Pulses (number of pulses/5h), amplitude of pulses (ng/ml) and nadir (ng/ml). In the control group, FSH secretion characteristics did not change between 20 and 30 weeks of age. In the experimental group, mean FSH concentrations decreased from 3.4 +/- 0.3 ng/ml/5h at 20 weeks of age to 0.36 +/- 0.1 ng/mL/ 5h at 30 weeks of age (P<0,05), which was also significantly lower than in the control group of the same age. Amplitude of FSH pulses in lambs of 30 weeks of age were significantly lower than in lambs of 20 weeks of age (4.4 +/- 0.5 versus 0.5 +/- 0.1 ng/mL respectively, P<0.05), and lower than that exhibited by control ewe lambs of 30 weeks of age. FSH pulse frequency did not change between lambs of 20 and 30 weeks of age in either group. Results show that the GnRH analogue is able to block the FSH secretion suggesting that the FSH secretion is dependant on GnRH stimulation in prepubertal female sheep.

Both epidemiological and clinical evidence suggest a relationship between the prenatal environment and the risk of developing diseases during adulthood. The first observations about this relationship showed that prenatal growth retardation or stress conditions during fetal life were associated to cardiovascular, metabolic and other diseases in later life. However, not only those conditions may have lasting effects after birth. Growing evidence suggests that prenatal exposure to steroids (either of fetal or maternal origin) could be another source of prenatal programming with detrimental consequences during adulthood. We have recently demonstrated that pregnant women with polycystic ovary syndrome exhibit elevated androgen levels compared to normal pregnant women, which could provide an androgen excess for both female or male fetuses. We have further tested this hypothesis in an animal model of prenatal androgenization, finding that females born from androgenized mothers have a low birth weight and high insulin resistance, that starts at an early age. On the other hand, males have low testosterone and LH secretion in response to a GnRH analogue test compared to control males and alterations in seminal parameters. We therefore propose that our efforts should be directed to modify the hyperandrogenic intrauterine environment to reduce the potential development of reproductive and metabolic diseases during adulthood.

LH and FSH secretions depend on the pulsatile secretion of GnRH from the hypothalamus.However, the grade of dependency as well as the relationship between pulses of GnRH and pulses of FSH secretion is less clear.Experiments in monkeys have shown that high GnRH pulse frequency favors LH secretion while low frequency of GnRH pulses preferentially stimulates the FSH secretion.The objective of the present work was to recognize the dependence of GnRH on the FSH secretion in prepubertal female sheep.A GnRH agonist analogue in slow release microcapsule preparation was used (Trp6-GnRH, (Decapeptyl®)) whose blocking effect on the LH release has been previously demonstrated.The analogue was injected intramuscularly every 4 weeks beginning at 20 weeks of age three times in five Suffolk ewe lambs.Another group of five lambs received the vehicle of Decapeptyl.Studies of FSH pulsatility were carried out at 20 (before the analogue agonist administration), 26 and 30 weeks of age.The CLUSTER program was used to identify characteristics of FSH secretion: transversal mean (ng/ml/5h), frequency of pulses (number of pulses/5h), amplitude of pulses (ng/ml) and nadir (ng/ml) .In the control group, FSH secretion characteristics did not change between 20 and 30 weeks of age.In the experimental group, mean FSH concentrations decreased from 3.4±0.3ng/ml/5h at 20 weeks of age to 0.36 ±0.1 ng/mL/ 5h at 30 weeks of age (P<0,05), which was also significantly lower than in the control group of the same age.Amplitude of FSH pulses in lambs of 30 weeks of age were significantly lower than in lambs of 20 weeks of age (4.4 ± 0.5 versus 0.5 ± 0.1 ng/mL respectively, P<0.05), and lower than that exhibited by control ewe lambs of 30 weeks of age.FSH pulse frequency did not change between lambs of 20 and 30 weeks of age in either group.Results show that the GnRH analogue is able to block the FSH secretion suggesting that the FSH secretion is dependant on GnRH stimulation in prepubertal female sheep.

Similar to women with Polycystic Ovary Syndrome (PCOS), female sheep treated prenatally with testosterone (T-females) are hypergonadotropic, exhibit neuroendocrine defects, multifollicular ovarian morphology, hyperinsulinemia and cycle defects. Hypergonadotropism and multifollicular morphology may in part be due to developmentally regulated increase in pituitary responsiveness to GnRH and may culminate in increased ovarian estradiol production. In this study, we utilized a GnRH agonist, leuprolide, to determine the developmental impact of prenatal testosterone exposure on pituitary-gonadal function and to establish if prenatal exposure produces changes in the reproductive axis similar to those described for women with PCOS. Eight control and eight T-females were injected intravenously with 0.1 microg of leuprolide acetate per kilogram of body weight at 5, 10 and 20 weeks of age. Blood samples were collected by means of an indwelling jugular vein catheter at 0, 3, 6, 9, 12, 18, 24, 30, 36, 42 and 48 hours after leuprolide. Area under the curve (AUC) of LH response to leuprolide increased progressively between the three ages studied (P<0.05). AUC of LH in T-females was higher than in control females of the same age at 5 and 10 weeks of age (P < 0.05), but similar at 20 weeks of age. AUC of estradiol response was lower at 10 but higher at 20 weeks of age in T-females compared to controls of the same age (P < 0.05). Our findings suggest that prenatal T treatment alters the pituitary and ovarian responsiveness in a manner comparable to that observed in women with PCOS.

Prenatally testosterone (T)-treated female sheep exhibit ovarian and endocrinological features that resemble those of women with polycystic ovarian syndrome ( PCOS), which include luteinizing hormone excess, polyfollicular ovaries, functional hyperandrogenism, and anovulation. In this study, we determined the developmental impact of prenatal T treatment on insulin sensitivity indexes (ISI), a variable that is affected in a majority of PCOS women. Pregnant ewes were treated with 60 mg testosterone propionate intramuscularly in cottonseed oil two times a week or vehicle [ control ( C)] from days 30 to 90 of gestation. T-females weighed less than C-females or males ( P < 0.05) at birth and at 5 wk of age. T-females had an increased anogenital ratio. An intravenous glucose tolerance test followed by an insulin tolerance test conducted after an overnight fast at 5, 20, and 30 wk of age ( n = 7 - 8/group) revealed that ISI were higher at 5 than 30 wk of age in C-females, reflective of a developing insulin resistance associated with puberty. T-females had higher basal insulin levels, higher fasting insulin-to-glucose ratio, and higher incremental area under the insulin curve to the glucose challenge. The ISI of T-females was similar to that of males. No differences in ISI were evident between groups at 20 and 30 wk of age. Mean basal plasma glucose concentrations and glucose disappearance and uptake did not differ between groups at any age. Our findings suggest that prenatal T treatment leads to offspring with reduced birth weight and impaired insulin sensitivity in early postnatal life.

Se ha demostrado, en borregas en crecimiento, que el ayuno esta asociado a resistencia insulinica como un fenomeno adaptativo a la baja ingesta calorica. La restriccion alimenticia es otra situacion natural o experimental que puede enfrentar la hembra en crecimiento, en la cual la disponibilidad de energia esta por debajo de los requerimientos indispensables para el crecimiento. La sensibilidad a la insulina podria cambiar tambien como una adaptacion fisiologica a la escasez de alimento. El objetivo del presente estudio fue reconocer si la sensibilidad a la insulina disminuye durante la restriccion alimenticia de borregas en crecimiento. La sensibilidad a la insulina se evaluo con el test de tolerancia a la glucosa endovenosa (TTGEV). Cinco borregas con crecimiento normal y cinco borregas con restriccion alimenticia por seis semanas, a partir de las 20 semanas de edad, se infundieron con una solucion esteril de glucosa (300 mg/kg peso corporal, solucion al 50%) en dos minutos. Se colectaron muestras de sangre desde la yugular mediante un cateter venoso 15 y 10 minutos antes de la infusion de glucosa, y a los 0, 3, 5, 7, 10, 13, 15, 17, 20, 23, 25, 27, 30 minutos despues del inicio de la infusion en cuyo plasma se midio glucosa e insulina. Las concentraciones de glucosa (g/l) e insulina (µUI/ml) se analizaron con la formula de Matsuda y DeFronzo para determinar el indice de sensibilidad a la insulina (ISI-Composite). Se calculo tambien el area bajo la curva de insulina basal, estimulada e incremental y la constante de utilizacion de la glucosa. El ISI-C fue menor en las borregas con restriccion alimenticia (636,43± 125,66) en comparacion con las borregas controles (1528,18 ± 297,61 P<0,05). En concordancia con estos resultados, el area bajo la curva incremental fue menor en las borregas controles (290,54 ± 79,45 ng/ml/30 min) que en las con restriccion alimenticia (642,16 ± 140,04 ng/mL/30 min, P<0,05). La constante de utilizacion de la glucosa fue similar en ambos grupos. Los resultados sugieren que la restriccion alimenticia conduce a una resistencia insulinica como un proceso adaptativo a la escasa provision de alimento en la oveja en crecimiento

It has been shown that fasting in growing ewes is associated with insulin resistance as an adaptative mechanism to the low energy supply. Food restriction is another experimental or natural situation that may occur for growing ewes where energy supply is under the requirement for growth. Insulin sensitivity may also change as a physiological adaptation to the shortage of food. The aim of the present study was to assess if insulin sensitivity decreases during food restriction in growing ewes. Insulin sensitivity was assessed by the intravenous glucose tolerance test (IVGTT). A glucose solution (300mg/kg body weight, 50% solution) was infused over two minutes into five normal growing 26-week old ewes and five 26 week-old ewes that had been restrictively fed from the age of 20 to 26 weeks. Blood samples were collected from the jugular vein of each ewe by an indwelling jugular vein catheter 15 and 10 min before and at 0, 3. 5. 7. 10, 13, 15 17, 20, 23, 25, 27 and 30 min after the initiation of the glucose infusion, and plasma glucose and insulin were measured by RIA. To determine the insulin sensitivity index (ISI), glucose and insulin concentrations were analyzed using the Matsuda and De Fronzo's formula (ISI-Composite). Basal, stimulated and incremental area under the curve of insulin and the glucose utilization constants were also calculated. ISI-C was lower in food-restricted female sheep (636.43 +/- 125.66) compared to normal growing females (1528.18 +/- 297.6 1), (P < 0.05). Concordant with this, incremental area under the curve of insulin was lower (290.54 +/- 79.45 ng/ml/30 min) in control than in food-restricted females (642.16 +/- 140.04 ng/mL/30 min, P < 0.05). The glucose utilization constant did not differ between groups. Results suggest that food restriction induces insulin resistance as ail adaptative process to the shortage of food in growing female sheep.

The objective of this study was to assess the effect of a GABA receptor antagonist, (Bicuculline) on the pulsatile LH secretion before, during and after fasting in ewe lambs. Five Suffolk ewe lambs of 20 weeks of age were subjected to fasting for 8 days. A study of LH pulsatility was performed before (day 0), after one and eight days of fasting and 48 hours after the end of fasting. This study consisted in collecting blood samples by means of an indwelling jugular vein catheter at 10 min intervals for 10 hours from 9am inwards hours. Five hours after the start of the pulsatility study, a bolus of Bicuculline (50 ug/kg BW) was given intravenously. Thus, the 10-hours study period was divided in two phases of 5-hours each: before and after bicuculline. Parameters of the LH secretion were determined by the CLUSTER program independently for both phases and compared by paired t-test. Basal parameters of LH secretion on each day of the study were analyzed with ANOVA for repeated measures and comparison of the means with the Newman Keuls's test. Body weight was recorded and basal levels of blood glucose, insulin and cortisol were also obtained before, during and after fasting.Body weight and basal plasma glucose concentrations decreased significantly after 8 days of fasting, however, insulin and cortisol did not change. Parameters of pulsatile LH secretion did not change with fasting or after 48 hours of refeeding. Bicuculline tended to increase (p<0.06) both mean plasma concentrations and amplitude of LH pulses before fasting (Day 0), but it had no effect on LH secretion on day 1, 8 of fasting or after two days of refeeding.Results suggest that GABA may be involved in the control of LH secretion in normally fed ewe lambs, however this control is not apparent during fasting. Fasting has an impact on body weight and plasma glucose concentrations but no effect on basal plasma levels of insulin. Plasma cortisol concentrations did not change suggesting that fasting did not evoke a stress condition.

Leptin, the product of the ob gene, has been proposed as a metabolic signal that regulates the secretion of GnRH/LH. This may be critical during prepubertal development to synchronize information about energy stores and the secretion of GnRH/LH. This study aimed to assess the effect of food restriction on the episodic secretion of leptin and LH in young female sheep. Five 20-week-old prepubertal females were fed a low-level diet for 10 weeks to maintain the body weight. Control females of the same age received food ad libitum. Blood samples were collected at 10-min intervals for six hours at 20, 26, and 30 weeks of age, and plasma leptin, LH, insulin and cortisol concentrations were measured. In the control group, no changes were found in pulsatile LH secretion characteristics. Mean LH concentrations and LH amplitude were lower in the food-restricted group than in the control group at 26 and 30 weeks of age. In the control group, pulsatile leptin secretion did not change. When compared to control lambs of the same age, the food-restricted group showed lower mean plasma leptin concentrations, pulse amplitude and plasma insulin levels, after 6 weeks of restriction (week 26), although by week 30, plasma leptin concentrations and plasma insulin rose to those of the control group. Leptin pulse frequency did not change, nor did mean plasma levels of insulin in the control group at any age studied. Mean plasma concentration of cortisol did not change within or between groups. These data suggest that plasma leptin concentrations may not be associated with the onset of puberty under regular feeding and natural photoperiod in lambs. Prolonged food restriction, however, induces metabolic adaptations that allow an increase of leptin during the final period, probably related to the development of some degree of insulin resistance.

Resumen en: The objective of this study was to assess the effect of a GABA receptor antagonist, (Bicuculline) on the pulsatile LH secretion before, during and after ...

La restriccion alimenticia retarda el inicio de la pubertad, producto de una disminucion de la secrecion pulsatil de LH y probablemente de FSH. El objetivo del presente trabajo fue conocer y comparar la secrecion pulsatil diurna de FSH entre borregas con crecimiento normal y con crecimiento retrasado, producido por la restriccion alimenticia. Cinco borregas Suffolk se alimentaron al 2% de su peso corporal con alimento concentrado en dos raciones diarias, mientras que otras 5 se alimentaron a voluntad a partir de las 20 y hasta las 30 semanas de edad. A las 20, 26 y 30 semanas de edad, se realizo un estudio de pulsatilidad de FSH. Este estudio consistio en la coleccion de muestras de sangre cada 10 minutos desde las 10 AM, por cinco horas, en cuyo plasma se midio FSH por RIA. Las caracteristicas de la secrecion pulsatil durante las cinco horas del estudio se reconocieron por medio del programa computacional CLUSTER. Los datos se analizaron con Andeva para muestras repetidas. Las concentraciones plasmaticas promedio (ng/ mL/5h) aumentaron en alrededor de un 50% en las borregas controles, entre las 20 y 30 semanas de edad, pero sin significancia estadistica. A las 30 semanas de edad, las borregas controles tenian una concentracion promedio de FSH plasmatica y una amplitud de pulsos un 50% mas alta que en las borregas con restriccion alimenticia. La secrecion de FSH no aumento estadisticamente entre las 20 y 30 semanas de edad en las borregas controles, mientras que tendio a disminuir en las borregas con restriccion alimenticia. La frecuencia de pulsos de FSH no mostro diferencias entre las edades o entre los grupos. Los resultados sugieren que la restriccion alimenticia tiene un efecto supresor parcial sobre la secrecion de FSH durante el desarrollo prepuberal de la borrega. El retraso en el inicio de la pubertad, debido a restriccion alimenticia en la borrega, se podria atribuir mas bien a una insuficiente secrecion de LH que a una deficiencia en la secrecion de FSH.

Food restriction delays the onset of puberty due to a low secretion of LH and probably the FSH as well. The objective of this work was to assess and to compare the diurnal pulsatile secretion of FSH in normal growing and in growth-retarded ewe lambs due to food restriction. Five Suffolk ewe lambs were fed at 2% of their body weight in two daily rations whereas the other 5 were fed ad-libitum from 20 and until 30 weeks of age and served as a control group. A FSH pulsatile study was conducted, before and after six and ten weeks of food restriction corresponding to 20, 26 and 30 weeks of age respectively. The FSH pulsatile study consisted in collecting blood samples every 10 minutes for 5 hours from 10 AM onwards. In the obtained plasma the FSH was measured by RIA. The characteristics of the pulsatile FSH secretion were assessed using the CLUSTER program. Data obtained from the CLUSTER program were analyzed with analysis of variance for repeated measures. Mean plasma FSH concentrations (ng/mL/5h) increased in almost 50% in control ewe lambs between 20 and 30 weeks of age but without statistical difference. At 30 weeks of age, control lambs had a 50% higher mean plasma FSH concentrations and mean FSH pulse amplitude than food-restricted lambs. FSH pulse frequency did not show any difference between ages within a group or between groups. Results suggest that food restriction has a partial suppressor effect on the FSH secretion. The delay on the onset of puberty due to food-restriction in the ewe lamb could be attributed more to an insufficient LH secretion GnRH-stimulated than to an inadequate FSH secretion.

The antler cycle of pudu is similar to other cervids, but unlike most boreal deer, male Southern pudu (Pudu puda) exhibits two seasonal peaks of LH and testosterone. In that respect, pudu is similar to roe deer. Whereas the antler cycle in some deer species, such as roe deer or white-tailed deer, is very sensitive to variation of testosterone, in other cervids, such as fallow deer or reindeer, a blockade of androgens with cyproterone acetate (CA) has little or no effect on the timing of the antler casting. In order to test the sensitivity of pudu antlers to variations of androgens, CA (administered 2x weekly at 50 mg/buck) was injected intramuscularly for 3 weeks in 5 adult male pudu, starting February 19 (late summer). Four other males of similar age served as controls. The experiment was performed at the University of Concepcion, Chile, latitude 36.6 degreeS. Blood samples were taken once a week between January 19 and April 3. In CA-treated bucks, the antlers were cast approximately 3 weeks after the initiation of CA treatment and a new antler growth began almost immediately. The antlers reached about 5 cm in length, before ceasing to grow at the end of April, when they became mineralized and were subsequently polished. CA had no effect on the already declining levels of LH. Plasma levels of testosterone in controls increased from February 15, whereas in CA-treated bucks remained depresses until March 21. It is concluded that similarly to white-tailed deer, the antler cycle of Southern pudu is very sensitive to manipulation of androgen levels.

Many studies have suggested that leptin modulates the gonadal axis. A synchronicity of luteinizing hormone (LH) and leptin has been described in humans, suggesting that leptin may modulate the episodic secretion of LH. The objective of this study was to establish whether episodic leptin secretion depends on the episodic LH secretion in prepubertal sheep. We used two different approaches. The first consisted of blocking the release of LH using a long-acting LH-releasing hormone (LHRH) agonist and analyzing the episodic LH and leptin secretions. The second method stimulated the pituitary gland with pulses of LHRH and again LH and leptin secretions were analyzed. Spring-born 20-wk-old Suffolk ewe lambs (n=5) received intra-muscularly a long-acting LHRH agonist (Decapeptyl®). Treatment was repeated at 24 and 28 wk of age. Control lambs (n=6) received the vehicle of Decapeptyl. Diurnal and nocturnal pulsatilities of LH and leptin were studied at 20 (before Decapeptyl injection), 26, and 30 wk. Blood samples were taken at 10-min intervals for 6 h, beginning at 10:00 am (diurnal sampling) and at 10:00 pm (nocturnal sampling). In all samples, LH and leptin were measured by radioimmunoassay, and pulsatile hormone secretion characteristics were assessed by the CLUSTER program. To characterize further the synchronicity between LH and leptin pulses, LHRH (10 ng/kg body wt) was injected at 60-min intervals, six times, to another five 30-wk-old ewe lambs, for the same time period as the pulsatility study. In the control group, LH secretion did not change between lambs of 20 and 30 wk of age. In LHRH agonist-treated lambs, LH secretion diminished from 20 to 30 wk of age and was lower than in control lambs at 26 and 30 wk of age (p<0.05). The transversal mean (ng/[mL · 6 h]) of leptin concentrations was different between control lambs of 20 wk of age and 26 and 30 wk of age (p<0.01). Contrary to the findings in LH secretion, in LHRH agonist-treated lambs, mean plasma leptin concentrations did not decrease. Furthermore, the mean diurnal and nocturnal leptin concentrations and the pulse amplitude were higher at 26 and 30 wk than at 20 wk in LHRH agonist-treated lambs (p<0.05). There were no differences between diurnal and nocturnal parameters of leptin secretion in both groups. There was no synchronicity between LH and leptin pulses. LHRH pulses significantly increased plasma LH concentrations, producing discernible LH pulses; however, leptin amplitude and leptin pulse frequency were not modified by the exogenous LHRH pulses, exhibiting no coincidence with LH pulses. The data suggest that pulsatile leptin secretion is independent of LH secretion in ewe lambs.

AbstractThe present study determined the effect of a GnRH and PGF2α treatment on proportion of cows detected in oestrus, the distribution of oestrous activity and subsequent fertility. The study also incorporated the use of ovarian ultrasound and milk progesterone assay to established a better overall assessment of treatments. Holstein-Friesian cows, averaging 9000-kg milk/lactation, and fed according to their requirements were used in the study. Cows were regularly cyclic; at least 60 days postpartum, had had two oestrous cycles and were clinically sound before being considered for either experiment. In Experiment 1, 274 cows were treated at random with an i.m. injection of 10 μg of GnRH (buserelin) followed 7 days later by 0.75 mg oftiaprost based on the ultrasound diagnosis of a corpus luteum. At that time and 3 days later, milk samples were collected and assayed for progesterone. Cows with progesterone concentrations >1 ng/ml were considered to have a corpus luteum, and luteolysis was assumed to have occurred when concentrations 3 days later were <0.8 ng/ml. In Experiment 2, 1431 cows were treated as above. The response to treatment was assessed by presence of a corpus luteum 7 d after GnRH treatment, oestrous detection rate, and distribution of heats and ultimately on conception rate. Conception rate was compared to untreated control cows inseminated by the same inseminator and using semen from the same sires. Artificial breeding was carried out after oestrous detection and pregnancy diagnosis was done by ultrasound. In Experiment 1, luteolysis was induced in 244/274 (89.1%) cows following PGF2α administration, with 198/214 (92.5%) been diagnosed correctly in heat and 16/214 (7.5%) been diagnosed in error based on progesterone profiles. Oestrous activity was most concentrated on day 3 (59.1%), with 20.7% and 16.7% of heats recorded on d 2 and d 4, respectively. When compared to untreated controls, GnRH-PGF2α treated cows had a better conception rate (56.6 vs. 39.5%, P<0.01). In Experiment 2, 1012/1431 (70.7%) had a CL 7 days after GnRH injection; 709/1012 (70.1%) cows were detected in oestrus, and 359/700 (51.3%) cows became pregnant after insemination compared to 182/434 (41.9%) of untreated controls (P<0.05). The utilisation of GnRH and PGF2α seems to be a useful synchronisation scheme based on AI after oestrous detection. However, variations in fertility after treatment demands a better understanding offactors affecting herd fertility under controlled schemes.

Several studies have suggested that leptin modulates hypothalamic-pituitary-gonadal axis function. A synchronicity of LH and leptin pulses has been described in healthy women and in patients with polycystic ovarian syndrome (PCOS), suggesting that leptin may modulate the episodic secretion of LH. The aim of the present investigation was to assess the episodic fluctuations of circulating LH and leptin during lactational amenorrhoea in fully breastfeeding normal and PCOS women at 4 and 8 weeks postpartum, in order to establish LH-leptin interactions in the reactivation of the gonadal axis during this period. Six lactating PCOS patients and six normal lactating women of similar age and body mass index were studied. During a 12 h period on the 4th and 8th weeks postpartum, blood samples were collected at 10 min intervals for 12 h (22:00-10:00). Serum LH and leptin concentrations were measured in all samples. For pulse analysis, the cluster algorithm was used. To detect an interaction between LH and leptin pulses, an analysis of co-pulsatility was employed. LH concentrations tended to increase in both groups between the 4th and 8th weeks postpartum; however, serum leptin concentrations were not modified. Leptin pulse frequencies were similar at the 4th and 8th weeks postpartum, and did not differ between groups. Moreover, leptin pulse frequency was higher than LH pulse frequency in both groups, and in the two study periods. There was no synchronicity between LH and leptin pulses, and there were no increments in leptin concentration during the night. The fact that leptin concentrations were not modified and no synchronicity between LH and leptin pulses was observed suggests that, during lactational amenorrhoea, circulating leptin is probably not involved as a primary signal in promoting the reactivation of pulsatile LH secretion.

AbstractControlled breeding schemes for oestrous detection constitutes a proactive technical response that balances the infrastructural requirement for a profitable dairy operation and the demands for optimal animal performance. The present study compared (a) the reproductive response of a treatment based on a short vs longer-acting PGF2α analogue (tiaprost vs luprostiol), and (b) the reproductive response after a treatment of GnRH-PGF2α vs PGF2α alone for synchronizing dairy cows. Holstein-Friesian cows averaging 9000 kg milk/lactation and fed according to their requirements were used in the study. Cows were cyclic, at least 60 days post partum and were clinically sound before being considered for the experiments. In Experiment 1, animals were synchronised using an i.m. injection of either 15 mg of luprostiol or 0.75 mg of tiaprost, based on ultrasonic diagnosis of a corpus luteum. Animals were inseminated at observed oestrus. In Experiment 2, cows were synchronised, at random, by either an injection of 10pg ofbuserelin (day 0) followed by 0.75 mg of tiaprost at day 7 (GnRH-PGF2α) orjust 0.75 mg of tiaprost (PGF2α). For both treatments only cows with an ultrasonically detected corpus luteum were treated. Animals were inseminated at oestrus. At the time of treatment and again 3 days later, milk samples were collected and assayed for progesterone by RIA. Cows with progesterone concentrations >1 ng/ml were considered to have corpus luteum. Luteolysis was considered to have occurred when concentrations of progesterone were > 1 ng/ml at day 0 and <0.8 ng/ml at day 3. In Experiment 1, both analogues gave similar results in terms of induced luteolysis [luprostiol: 36/39 (92.3%) vs tiaprost: 36/41 (87.8%)], oestrous detection efficiency [luprostiol: 26/36 (72.2%) vs tiaprost: 30/36 (83.3%], oestrous distribution [day 2, 3 and 4, respectively: luprostiol: 26.9%, 50.0%, 19.2% vs tiaprost: 36.7%, 50.0%, 13.3%], and conception rates [luprostiol: 12/25 (48.0%) vs tiaprost: 14/28 (50.0%); P>0.05]. In Experiment 2, oestrous detection efficiency, interval to oestrus and conception rate were similar between treatments [97/149 (65.1%), 71.1 h, 43/95 (45.3%) for PGF2α vs 130/188 (69.1%), 68.2h, 65/126 (51.6%) for GnRH-PGF2α, respectively]. However the oestrous distribution was more concentrated in GnRH-PGF2α treated animals (P<0.01).

The first ten years of research on pudu physiology and behavior concentrated on the investigation of hormone profiles in males. Basic and seasonal levels of LH, FSH, testosterone, prolactin, IGF-1, cortisol and triiodothyronine were determined. The seasonal fluctuations of reproductive and other hormones are related to the reproductive and the antler cycles and the social rank of individual males. In addition, basal and poststimulatory levels of cortisol, growth hormone (GH), LH, FSH and testosterone were reported after ACTH and GnRH challenge tests. Most blood levels of hormones in male pudu are in the low range often less than half of hormonal levels of another small cervid, the roe deer. Pudu responds quickly to simulated stress and GnRH elicits a vigorous increase of LH and T in the dominant males. The next phase of our research is now concentrated on the reproductive physiology of the female pudu, where a delayed implantation of the embryo is suspected.