The correlation between protein turnover and serum thyroid hormone levels was studied in 10 children, ages 1 to 16 years subsequent to severe burn injuries. In contrast to published studies that have shown depression of triiodothyronine (T3) and elevations of reverse T3 (rT3) in stressed patients, no change was found in the mean level of T3 and a 69% decrease in rT3 compared to healthy controls of similar age. Whole body rates of protein synthesis and breakdown were determined using a [15N]glycine turnover technique. The difference between synthesis and break-down was negatively correlated with the ratio, rT3/T3 in serum. Thus, in burned children, a decrease in N balance was associated with a rise in rT3/T3 which is qualitatively similar to that observed in fasted individuals or in stressed patients who may be semistarved.

Radioimmunoassay was used to determine plasma corticosterone concentration (PCC) in turkeys inoculated with Pasteurella multocida via either the palatine air spaces or the drinking water and maintained at high (33.4-37.4 C), low (2.6-5.3 C) and moderate )19.8-22.4 C) temperatures in temperature-controlled chambers. In uninoculated turkeys maintained at high temperatures, the PCC was generally lower than in turkeys maintained at moderate temperatures, whereas the opposite occurred in turkeys maintained at low temperatures. After inoculation with P. multocida, all groups of inoculated turkeys showed an increase in the average PCC, which attained a level in some turkeys of over 40 ng/ml, in relation to the average in the uninoculated turkeys, which ranged from 1.8 to 27.3 ng/ml. This increase was proportional to the severity of the infection that developed. The PCC was found to be a sensitive indicator of an incubating infection of P. multocida, since it was markedly increased in turkeys that were bled one day before the onset of depression. In turkeys that were inoculated via the palatine air spaces and maintained at 20 C, the PCC on the day of inoculation was significantly (P less than 0.05) lower in the turkeys that later died than in those that survived. Generally, the PCC was higher in the turkeys that either died between 5 and 10 days after inoculation or were depressed aa the end of the experiment on day 10, relative to the turkeys that were alert at the end of the experiment.

A method of determining corticosterone concentration in turkey plasma was developed using radioimmunoassay. Compared to fluorometric analysis and competitive protein-binding radioassay, this method had the following advantages: 1) results were consistent, 2) the method was simple and rapid to perform, 3) only 20 lambda of plasma was required, 4) all procedures were performed using the same tube except for counting, and 5) unknown and standard samples were treated identically. The coefficient of variation with the 5 ng/ml standard sample between 14 sets of assays was 12.6% and the average coefficient of variation within duplicate assays of unknown samples randomly selected from each of the 14 series was 4%. Using this method, there was an increase in the average plasma corticosterone concentration in all groups of inoculated turkeys one day after inoculation of Pasteurella multocida which was significantly (P less than .05) greater than that of the noninoculated groups.

We studied the correlation between protein turnover and serum thyroid hormone levels in 10 children, age 1-16 yrs., with severe burn injuries. Whole body protein synthesis (S) and breakdown (C) were determined using an (15N) glycine infusion technique. Patients were maintained in good nutritional status as evidenced by a net anabolism (S,C) in 14 of 21 studies. There was no change in mean levels of serum 3,3′,5′ triiodothyronine (T3), a decrease in serum thyroxine (T4) and a suppression of serum reverse T3 levels. The difference between protein synthesis and breakdown (S minus C) was negatively correlated with the rT3/T3 ratio (r=-.0.46,p .05). Thus, a decrease in N balance was associated with a rise in rT3/T3 ratio, similar to observations made in humans during fasting or severe stress. These studies suggest that the rT3/T3 ratio may be useful clinically as an indicator of relative dietary energy deficiency.

An athyreotic infant presented with hypothyroidism at 12 months of age. History, detailed growth data and photographs documented absence of symptoms and maintenance of normal growth (>90%ile) until age 10 months when breast feeding was discontinued. Yet, his bone age was that of a newborn, thus supporting the congenital nature of athyreosis. These observations suggested that breast feeding attenuated hypothyroidism possibly by providing significant quantities of thyroid hormones in the milk. To test this hypothesis we measured T4, T3 and reverse T3 (rT3), in serial breast milk samples collected from five “La Leche League” volunteers between 96 days prior, to 128 days after delivery. RIA determinations of iodothyronines were preceeded by alcohol extraction to correct for variations in protein and lipld content. During pregnancy breast milk T4 averaged 1.3ug% and fell to 0.8ug% within 3 days postpartum. With delivery there was a highly significant increase in milk T3 content from 145ng% to 283ng%, levels far exceeding serum T3 concentration. This postpartum rise in breast milk T3 was apparently not due to a shift in deiodination of T4, since rT3 levels were low and remained unchanged. (5.2-7.2ng%) The rise in milk T3 postpartum preceeded the fall in total protein, albumin and immunoglobulin and the rise in α1-antitrypsin content. It is concluded that: a) T3 is secreted selectively by the mammary gland, b) human breast milk contains sufficient thyroid hormone to mitigate congenital hypothyroidism.

Recent data on various environmental stressors and blood hormone patterns are presented for lactating cattle. Known stressor effects of such factors as environmental temperature, air pollution, and noise on the plasma thyroxine, growth hormone, cortisol, prolactin, progesterone, luteinizing hormone, epinephrine, and norepinephrine of lactating cattle are discussed. Information on stressor effects is lacking on glucagon, insulin, vasopressin, calcitonin, oxytocin, thyrotrophic hormone, follicle stimulating hormone, melatonin, parathyroid hormone, and estrogens in the lactating cow. The importance of evaluating both the effect of environmental stressor and of production or lactation intensity is emphasized in the overall interpretation of changes in hormone of plasma. The short and long term environmental heat effects on thyroxine, cortisol, and growth hormone are clear with initial increases due to acute stressors and a decline of amounts in plasma after prolonged exposure to stressors. The relationship of amounts in plasma of these hormones to milk production appears to be related directly for cortisol, growth hormone, and prolactin with an inverse relationship with thyroxine. Epinephrine and norepinephrine seem to be elevated with prolonged environmental heat stress. However, the influence of intensity of lactation has not been measured. Hormones in plasma as they relate to stressor effects and milk production are important as potential indicators of the physiological state of a cow and reflect the physiological compensations a cow undergoes at various lactation intensities and/or stress exposure.

The effects of milk yield (lactational intensity) and short (18 h) moderate heat exposure (30 C) on plasma thyroxine were studies in spring (March) and fall (October) in the University of Missouri dairy herd. Spring and fall thyroxine did not differ at thermoneutral temperature of 15 C. The relatively short moderate heat exposure had no effect within production groups either in the spring or fall sampling. As stage of lactation progressed, thyroxine also increased. The effect of stage of gestation was an elevation in the first trimester (compared to nonbred) that progressed into the second and third trimesters. In both spring and fall (15 C), the high production group (adjusted and unadjusted) had lower plasma thyroxine compared with middle and low production groups, while no difference in adjusted means was significant between middle and low production groups. Correlations were --.51 between plasma thyroxine and lactational intensity in both spring and fall. The short exposure to moderately high environmental temperature intensified the relationship of lowered plasma thyroxine in hibh producing cows, and thyroxine was negatively correlated (--.63 and --.64) with lactational intensity. Because total plasma thyroxine is inversely related to lactational intensity, studies are warranted to quantitate free hormonal concentrations and utilization by dairy cattle with varying productivity.

Six mature nonlactating Holstein cows were subjected to a test procedure of a sham period (saline injection) of 10 days that prededed and followed each 14 day TRH treatment period at 18.5 and 35 degrees. The objective of this study was to determine the effect of intramuscular injection of TRH (400D 35 DEGREES. The results indicate that im administration of TRH is effective in elevating plasma thyroxine levels at both 18.5 and 35 degrees, but the response is diminished after 7 days at 18.5 degrees and ineffective in sustaining or elevating plasma thyroxine levels in cattle after 6 days of TRH administration at 35 degrees.

1.1. Plasma glucocorticoids were measured in six species of desert rodents. The data indicated that the primary glucocorticoid in all desert rodents is corticosterone.2.2. Corticosterone plasma levels appeared to be related to ecological distribution of desert rodents.3.3. It is suggested that lower corticosterone plasma levels may play an adaptive role in water conservation and lowered metabolic rates of desert rodents.

The repeated systemic infusion of TRH (200 mug, twice daily) was effective in repeatedly elevating plasma T4 levels (20-40 min postinfusion) for the 3 experimental days. The post-TRH treatment (saline infusion) exhibited a depression of plasma thyroxine levels, possibly explained by previous high thyroxine levels exerting a suppressive effect on the hypothalamic-pituitary-thyroid axis. A depression of plasma glucocorticoid levels was shown within 1 hr in both experiments after TRH administration. The results indicate that TRH administration (systemic) is effective in temporarily elevating thyroxine levels and simultaneously lowering plasma glucocorticoids in cattle.

This study indicates that at 15 degrees higher producing cattle (milk yield) have higher plasma glucocorticoid concentrations compared to lower producing cattle with glucocorticoid levels appearing to be positively correlated with lactational intensity. Short term thermal (30 degrees) exposure for 18 hr resulted in glucocorticoid levels being markedly lower in high producing cattle compared to low producers. This shift at 30 degrees (after 18 hr) is possibly due to different time sequence of glucocorticoid response to thermal exposure between high and low producing cows. These data support the concept that glucocorticoids assist the animal in efficiently meeting the greater energy demand of lactation and further studies should be undertaken to denote free plasma levels and their utilization by dairy cattle at various levels of milk production.

The objective of this study was to determine acute effects of SO2 and simultaneous exposure to SO2 and heat on plasma glucocorticoids and thyroxine levels. Male mice (160) were divided into four treatment groups: control, heat, SO2, SO2 and heat. These groups were further divided into four time exposures, 30 min, 1, 12 and 24 hours. The effect of heat and SO2 as compared to heat or SO2 alone appears to be a more rapid and prolonged elevation of glucocorticoids, while thyroxine levels showed a more rapid depression compared to heat and a greater depression as compared to the SO2 treatment group.

1.1. The fur-chewing chincillas showed increased thyroid activity (P < 0·5), increased adrenalcortical function (P < 0·05) and decreased rectal temperature (P < 0·01).2.2. This study suggested that increased endocrine activity could be due to the loss of insulation over the fur-chewed areas.3.3. It is possible, however, that endocrine activity could be a stimulus for fur-chewing.4.4. It is also possible that fur-chewing can be initiated or its incidence increased by “non-specific stressors’.