Polycystic ovary syndrome (PCOS) is associated with impaired ovarian steroidogenesis and ovulation, which necessitates the development of effective ovulation inducers for PCOS. The aim of the study was to evaluate the effects of allosteric luteinizing hormone receptor agonist TP03 and human chorionic gonadotropin (hCG) on ovarian steroidogenesis, as well as ovulation in prepubertal female rats with dehydroepiandrosterone(DHEA)-induced PCOS. Taking into account differences in progesterone levels, cohorts with high (PCOS(H)) and low (PCOS(L)) progesterone were formed and treated with Follimag and Cetrotide. After 48 h, TP03 (25 mg/kg) or hCG (25 IU/rat) were injected, and hormone levels, gene expression, and ovarian morphology were assessed. The PCOS(H)-cohort exhibited irregular estrous cycles, ovarian cysts, and increased ovarian mass and estradiol levels, but the number of corpora lutea (CL) was maintained. In the PCOS(L)-cohort, ovarian weight was increased, and Star, Cyp11a1, and Adamts1 gene expression as well as the CL number were decreased. In both cohorts, TP03 and hCG increased progesterone levels and the expression of steroidogenesis (Star, Cyp11a1) and ovulation (Cox2, Adamts1, Egr1) genes, as well as inducing CL formation. Thus, TP03, like hCG, stimulates steroidogenesis and ovulation in PCOS-rats with different progesterone levels, which provides the first evidence of the effectiveness of allosteric LHR agonists as ovulation triggers in PCOS.

The hypothalamic-pituitary-gonadal (HPG, gonadal) axis is responsible for regulating reproductive functions, and its activity is regulated by numerous hormones, including leptin and insulin. Their primary targets are hypothalamic neurons expressing gonadotropin-releasing hormone (GnRH), which regulate secretion of gonadotropins and, thus, control puberty and fertility. The key function of leptin and insulin in hypothalamus is to mediate functional relationship between the energy availability and expenditure, on the one hand, and reproduction, which is determined, in part, by the activity of GnRH neurons, on the other. The effects of leptin and insulin on the GnRH neurons are typically indirect and mediated through other hypothalamic neurons, providing more specialized, multi-level regulation of their activity. The targets of leptin and insulin are various types of kisspeptin (Kiss1)-expressing neurons, as well as neurons expressing proopiomelanocortin (POMC, a precursor of anorexigenic melanocortin peptides), and the orexigenic factors – agouti-related peptide (AgRP) and neuropeptide Y (NPY). The Kiss1- and POMC-expressing neurons positively regulate GnRH-neurons, while the AgRP/NPY neurons are primarily involved in their negative regulation. The effects of leptin and insulin on the Kiss1-, POMC-, and AgRP/NPY-neurons, and consequently on the GnRH-neurons and the HPG axis, depend on physiological state of the organism, including its metabolic status, puberty, and gender. These effects are significantly altered in obesity and type 2 diabetes mellitus, thereby contributing to etiology and pathogenesis of the associated reproductive disorders. This review focuses on the current state of knowledge on the roles of insulin- and leptin-mediated regulation of the hypothalamic HPG axis in health and disease, as well as on the unresolved issues in this area. Understanding molecular basis of this regulation opens up broad prospects for the development of new pharmacological approaches to restoring reproductive function in obesity and diabetes.

The approaches to correct thyroid deficiency include replacement therapy with thyroid hormones (THs), but such therapy causes a number of side effects. A possible alternative is thyroid-stimulating hormone (TSH) receptor activators, including allosteric agonists. The aim of this work was to study the effect of ethyl-2-(4-(4-(5-amino-6-(tert-butylcarbamoyl)-2-(methylthio)thieno[2,3-d]pyrimidin-4-yl)phenyl)-1H-1,2,3-triazol-1-yl) acetate (TPY3m), a TSH receptor allosteric agonist developed by us, on basal and thyroliberin (TRH)-stimulated TH levels and the hypothalamic-pituitary-thyroid (HPT) axis in male rats with high-fat diet/low-dose streptozotocin-induced type 2 diabetes mellitus (T2DM). Single and three-day administration of TPY3m (i.p., 20 mg/kg) was studied, and the effect of TPY3m on the HPT axis was compared with that of levothyroxine. TPY3m increased TH levels when administered to both healthy and diabetic rats, normalizing thyroxine and triiodothyronine levels in T2DM and, unlike levothyroxine, without negatively affecting TSH levels or the expression of hypothalamic and pituitary genes responsible for TSH production. TPY3m pretreatment preserved the stimulatory effects of TRH on TH levels and thyroid gene expression. This indicates the absence of competition between TPY3m and endogenous TSH for TSH receptor activation and is supported by our in vitro results on TPY3m- and TSH-stimulated adenylate cyclase activity in rat thyroid membranes. Morphological analysis of thyroid glands in diabetic rats after three-day TPY3m administration shows an increase in its functional activity without destructive changes. To summarize, TPY3m, with the activity of a partial allosteric agonist of the TSH receptor, was created as a prototype of drugs to correct thyroid insufficiency in T2DM.

Impaired cardiovascular function in metabolic syndrome (MS) and type 2 diabetes mellitus (T2DM) is not adequately studied, and data on changes in electrocardiogram (ECG) parameters, including in rodent models of MS and T2DM, are contradictory and ambiguous. Aim of the study was to investigate ECG parameters in models of MS and T2DM and to identify possible correlations between impaired glucose tolerance and the severity of changes in ECG parameters. Material and methods. Male Wistar rats were used in the experiments. MS was induced by a high-fat diet (HFD) for 17 weeks; T2DM was induced by a combination of HFD and streptozotocin injection (HFD + STZ): 11 weeks of HFD followed by an injection of streptozotocin and continued HFD for another 6 weeks. Control animals were kept on a standard diet. Results. The glucose tolerance test confirmed the development of impaired glucose tolerance to the prediabetic level in the HFD group and to the diabetic level in the HFD+STZ group. ECG changes were found only in the HFD+STZ group: a significant (compared to the control and HFD group) increase in the amplitude and area T wave on the ECG was shown. Conclusions. Pronounced ECG abnormalities develop only in the model of T2DM, but not in the MS model.

Objective: Despite the fact that hypothyroid conditions, including autoimmune thyroiditis, are widespread pathologies, the possibilities of their pharmacological correction are very limited, including, mainly, the replacement therapy with thyroid hormones (THs). However, such therapy is characterized by many side effects, in connection with which alternative ways of stimulating the thyroid system are being developed, including the use of low-molecular regulators. Their target is allosteric sites located in the transmembrane domain of the thyroid-stimulating hormone (TSH) receptor. The aim of the study was the synthesis and physicochemical characterization of a new compound TPY7, methyl 2-(4-(4-(5-amino-6-(tert-butylcarbamoyl)-2-(methylthio)thieno[2,3-d]pyrimidin-4-yl)phenyl)-1H-1,2,3-triazol-1-yl) acetate, a methylated analogue of TPY3m, a TSH receptor agonist developed by us earlier, and to study the ability of TPY7 (in comparison with TPY3m) to influence the levels of total (tT4) and free (fT4) thyroxine and free triiodothyronine (fT3) and the expression of thyroglobulin (Tg), thyroid peroxidase (Tpo), and type 2 deiodinase (Dio2) genes in the thyroid gland of rats with one- and five-day administration, including stimulation of the thyroid system with thyroliberin (TRH). Material and methods: Blood levels of TG and TSH were assessed using enzyme immunoassay. Expression of genes responsible for TG synthesis was measured using real-time PCR. Results and discussion: When administered to rats, TPY7 dose-dependently increased the production of tT4 and fT3, and at a dose of 15 mg/kg (i.p.) also increased the expression of the Tpo and Dio2 genes responsible for the synthesis and conversion of THs. Its stimulating effect was maintained after five days of administration, indicating the absence of significant desensitization of the TSH receptor and its signaling cascades with long-term exposure to TPY7. In terms of the effectiveness of the stimulating effect on the thyroid system, TPY7 was inferior to TPY3m, although to a small extent. At the same time, unlike TPY3m, TPY7 potentiated the effects of TRH, increasing its stimulating effect on the levels of tT4 and fT3 in the blood and on the expression of the Dio2 gene in the thyroid gland. Conclusions: Thus, we have developed for the first time an active in vivo allosteric ligand of the TSH receptor with the activity of a partial agonist and a positive allosteric modulator (ago-PAM). TPY7 is a prototype for the creation of drugs that can be used to treat hypothyroidism and as stimulators of radioactive iodine uptake by thyrocytes in thyroid cancer radiotherapy.

Graves' disease is caused by overactivation of the thyroid-stimulating hormone receptor (TSHR). One approach for its treatment may be the use of negative allosteric modulators (NAM) of TSHR, which normalize TSHR activity and do not cause thyroid hormone (TH) deficiency. The aim of the work was to study the effect of a new compound 5-amino-4-(4-bromophenyl)-2-(methylthio)thieno[2,3-d]pyrimidine-6-carboxylic acid N-tert-butylamide (TPY4) on the basal and TSH-stimulated TH production in cultured FRTL-5 thyrocytes and on basal and thyrotropin-releasing hormone (TRH)-stimulated TH levels in the blood of rats. TPY4 stimulated TH production by thyrocytes and increased TH levels when administered intraperitoneally and orally in rats. It also decreased the TSH-stimulated TH production in thyrocytes and the TRH-stimulated TH levels in rats. Thus, TPY4 is the first known allosteric regulator of TSHR, combining the properties of NAM and a partial agonist, and can be considered as a prototype of drugs for the treatment of Graves' disease.

BACKGROUND:Wilson disease (WD) is a hereditary autosomal-recessive disorder of copper metabolism caused by mutations in the ATP7B gene, which also leads to dysregulation of lipid metabolism. In Atp7b-/--mice, a high-calorie diet (HCD) aggravates WD symptoms. However, it remains unknown whether HCD induces similar effects in asymptomatic Atp7b+/--heterozygotes. OBJECTIVES:This study aimed to determine whether HCD induces a WD-like phenotype in Atp7b+/--mice. METHODS:Five-month-old male C57BL/6 Atp7b+/+ and Atp7b+/--mice (n = 3-6/group) were fed either standard diet (SD, 326 kcal/100 g) or HCD (420 kcal/100g) for 18 wk. Serum copper, glucose, insulin, lipid profile, and oxidase activity were measured. Liver, subcutaneous adipose tissue (SAT), and visceral adipose tissue (VAT) were analyzed via histology and electron microscopy. Expression of copper metabolism-related genes (CMRGs) was assessed by RT-qPCR (Quantitative Real Time PCR). MANOVA with Tukey post hoc test was used for statistical analysis using the R software. RESULTS:Genotype had no effect on concentrations of copper, triglycerides, total cholesterol, high-density lipoprotein (HDL) cholesterol/non-HDL cholesterol, low-density lipoprotein (LDL) cholesterol/non-LDL cholesterol, atherogenicity index, or oxidase activity. Glucose concentrations were significantly reduced in Atp7b+/-(HCD)-mice (3.9 compared with 7.6 mM/L, P < 0.05), whereas insulin concentrations were elevated in Atp7b+/+(HCD)-mice (0.5 compared with 0.1 μg/L, P < 0.05). Liver steatosis and fibrosis were found in Atp7b+/-(SD) and worsened by HCD. Adipocyte hypertrophy was observed in both SAT and VAT under HCD [2734 μm2 in Atp7b+/+(HCD) and 1382 μm2 in Atp7b+/-(HCD) compared with 1040 μm2 in Atp7b+/+(SD) and 1934 μm2 in Atp7b+/-(SD), P < 0.05]. White-to-brown fat conversion was noted in the SAT of Atp7b+/-(HCD)-mice. In the liver, HCD reduced Ctr1 and Cp gene expression by 60% and 30%, respectively (P < 0.05); in SAT, all assessed CMRGs were upregulated by 50%-85% (P < 0.05); whereas no changes were detected in VAT. CONCLUSIONS:Atp7b+/-(SD)-mice display hepatic and adipose abnormalities, aggravated by an HCD, suggesting that WD heterozygotes may be diet sensitive, highlighting the relevance of dietary management to prevent metabolic and hepatic complications.

The “cafeteria diet,” which includes an excess of saturated fats and easily digestible carbohydrates, leads to obesity and is a risk factor for the development of type 2 diabetes. Metformin (MF) is often used to correct diet-induced obesity (DIO), but in some patients it causes serious side effects, which requires a reduction in its doses, including through combined use with drugs that potentiate the effects of MF. A candidate for the role of such drugs is intranasally administered insulin (INI), which itself has a restorative potential in the treatment of metabolic disorders. The goal of the work was to study the effectiveness of a three-week combined use of MF (100 mg/kg/day, perorally) with INI in two doses (1.5 and 6.0 IU/kg/day) for the correction of metabolic and hormonal disorders in male rats with DIO induced by a “cafeteria diet”. It was shown that in rats with DIO, the combination of MF and INI normalized body weight and abdominal fat, restored glucose homeostasis, lipid metabolism, basal and glucose-stimulated levels of insulin and leptin. Compared with MF monotherapy, the combined use of MF and INI more effectively restored sensitivity to insulin, assessed by a decrease in the insulin resistance index, and also normalized glucose tolerance, assessed by a decrease in the value of AUC0-120, the integrated area under glucose concentration curves in the glucose tolerance test. The combination of MF with INI at a dose of 1.5 IU/kg/day normalized the hormonal status of the thyroid system, disturbed in DIO, while the combination of MF with INI at a dose of 6 IU/kg/day worsened the hypothyroid state, mainly due to hyperactivation of thyroid-stimulating hormone secretion and the development resistance of the thyroid gland to it. Thus, for the correction of metabolic and hormonal parameters in DIO, including the restoration of the functions of the thyroid system, the use of MF with relatively low doses of IVI, which does not have a negative effect on the thyroid axis, is promising.

In experiments on rats, we studied the effect of 5-day intraperitoneal (15 mg/kg/day) and oral (40 mg/kg/day) administration of compound TPY3m, a stimulator of the production of thyroid hormones by the thyroid gland developed by us, on the blood levels of thyroxine, triiodothyronine, and thyroid-stimulating hormone and on morphology of the thyroid gland. With both routes of administration, TPY3m caused a sustained moderate elevation of thyroid hormones, mainly thyroxine, with little effect on the level of thyroid-stimulating hormone. TPY3m did not reduce the stimulating effect of thyroliberin on the levels of thyroid hormones and had no damaging effect on the thyroid gland. During long-term administration, compound TPY3m stimulates the production of thyroid hormones without weakening the activity of the thyroid axis. Thus, TPY3m is a prototype of drugs for correcting thyroid hormone deficiency.

Autoimmune hyperthyroidism (Graves’ disease), which is caused by stimulating autoantibodies to the thyroid-stimulating hormone receptor (TSHR), and thyroid tumors, caused by a constitutively increased activity of this receptor, are widespread and have a poor prognosis. The drugs used to treat them are low effective and have many side effects. One of the therapeutic approaches to these thyroid diseases may be the use of TSH receptor allosteric regulators with an activity of inverse agonists. This work was aimed to study the effects of the compound TP48, previously synthesized in our laboratory, and a newly synthesized compound TPY5, with both of them referring to thieno[2,3-d]-pyrimidines, on basal and thyrotropin-releasing hormone (TRH)-stimulated levels of thyroid hormones (THs) in the rat blood and on the expression of genes responsible for TH synthesis in the rat thyroid gland. TP48 and TPY5 effectiveness was studied upon both intraperitoneal (20 mg/kg) and peroral (40 mg/kg) administration. Using ELISA, blood levels of free (fT4) and total (tT4) thyroxine, as well as free (fT3) and total (tT3) triiodothyronine, were assessed, including during stimulation with intranasal TRH (300 µg/kg). Gene expression for thyroid peroxidase (Tpo), thyroglobulin (Tg), Na+/I– symporter (Nis), type 2 deiodinase (Dio2), and TSH receptor (Tshr) in the thyroid gland was assessed by PCR. TPY5, administered via both routes, reduced both basal and TRH-stimulated plasma TH levels, while TP48 suppressed TH production only after intraperitoneal administration. Peroral TPY5 significantly reduced basal Tpo expression, as well as TRH-stimulated Tg and Dio2 expression. Intraperitoneal TP48 reduced only TRH-stimulated Tg and Dio2 expression. Quite surprisingly, peroral TPY5 and intraperitoneal TP48 reduced basal Tshr expression but did not prevent its inhibition by TRH. Thus, the novel compound TPY5 exhibits the activity of a TSH receptor inverse agonist and is effective when administered perorally, which is more in demand in medicine; it can be considered as a prototype of drugs to treat autoimmune hyperthyroidism and thyroid tumors.

Mechanisms of adaptation to prolonged low temperature exposures, aimed at increasing thermogenesis and altering metabolism, include an increase in the activity of the hypothalamic-pituitary-thyroid (HPT) axis. Therefore, it remains a relevant task to explore the balance of thyroid hormones (THs), expression and activity of enzymes responsible for their synthesis in the thyroid gland (TG), expression of the main components of the HPT axis, as well as to investigate the effect of thyroid stimulating hormone (TSH) receptor antagonists on these indices when administered to animals exposed to cold. This work was aimed to study blood TSH and TH levels and the expression of hypothalamic, pituitary and thyroid genes involved in their synthesis and secretion in male rats exposed to low temperatures (5°C) for 10 days, as well as to assess the effect of a single treatment of animals with the thieno[2,3-d]-pyrimidine derivative TPY1, an original allosteric TSH receptor antagonist, on these indices. Cold-exposed rats developed T3 hyperthyroidism, which was associated with a decrease in the thyroxine level due to an increase in its conversion to T3, as indicated by an increase in the T3/T4 ratio and type 2 deiodinase (DIO2) expression in the TG. Compared to controls, the expression of thyroidal Tg and Nis genes, encoding thyroglobulin and Na+/I– symporter, increased in the TG of hyperthyroid rats. TPY1 normalized the T3 level and decreased Tg and Nis expression, suggesting a TPY1-induced decrease in the TSH-stimulated TSH receptor activity. TPY1 also increased the gene expression of the TSH β-subunit and thyroliberin receptor genes in the pituitary gland, which may be due to a higher threshold of sensitivity of thyrotrophs to the inhibitory effect of T3 under conditions of long-term T3 hyperthyroidism. A distinctive feature of cold-induced T3 hyperthyroidism in rats was the tissue specificity of changes in DIO2 gene expression, namely its increase in the TG and a decrease in the hypothalamus, as well as the retention of elevated DIO2 gene expression in the TG after TPY1 treatment. Thus, prolonged exposure of rats to cold leads to the development of pronounced T3 hyperthyroidism with increased expression of genes responsible for TH synthesis, while the treatment with an allosteric TSH receptor antagonist significantly normalizes these indices.

The search for natural biologically active substances having a neuroprotective effect against cerebral ischemia-reperfusion injury is one of the major priorities of modern neuroscience and medicine. Intranasal insulin (INI) exerts a pronounced restorative effect on various neurodegenerative diseases, but the mechanisms of its action and its therapeutic effects in cerebral ischemia have not been well studied, including in type 2 diabetes mellitus (DM2) which increases the risk of cerebrovascular dysfunction. The aim of the work was to study the effect of INI on metabolic parameters and inflammatory factors in male Wistar rats with DM2, exposed to cerebral ischemia, as compared to nondiabetic animals. DM2 was induced by a combination of high-fat diet and low-dose (25 mg/kg) streptozotocin administration. Cerebral ischemia was studied in a rat model of global forebrain ischemia-reperfusion (IR) injury induced by occlusion of both common carotid arteries, followed by a 7-day reperfusion. Two h after the end of ischemic exposure, the rats were treated with INI at a dose of 0.5 or 2.0 IU/rat, after which the drug was administered at the same dose, once a day, for the following 7 days. INI was found to prevent body weight loss in both nondiabetic and DM2 IR-exposed rats, while elevating plasma total cholesterol levels and epididymal fat fraction in IR-exposed nondiabetic animals only. In IR-exposed DM2 rats, INI (at both doses used) reduced postprandial plasma levels of glucose and insulin, indicative of improved glucose tolerance, as well as plasma levels of inflammatory factors, C-reactive protein (at a dose of 0.5 IU/rat/day), and tumor necrosis factor-α (at a dose of 2 IU/rat/day), indicative of its anti-inflammatory potential. Thus, a post-IR course treatment with INI improves metabolic parameters and abates inflammatory responses in DM2 rats, which may be in high demand when correcting ischemic stroke in patients with DM2.

BACKGROUND: Limiting or temporally stopping breastfeeding can lead to the development of metabolic syndrome in adulthood, which requires the development of approaches for its prevention and correction. One such approach is treatment with metformin or intranasal insulin. Since the targets of these agents differ and may complement each other, it has been suggested that their combined use could be effective. AIM: To study the effect of a four-week co-administration of metformin (orally, 120 mg/kg/day) and intranasal insulin (1.2 IU/kg/day) in male rats with metabolic syndrome, induced by breastfeeding disruption on postnatal days 19–21, on their metabolic and hormonal parameters. MATERIALS AND METHODS: The study treatment was compared with monotherapy using the same drugs. RESULTS: It was found that adult male rats with disrupted breastfeeding developed obesity, dyslipidemia, hyperleptinemia, impaired glucose tolerance, and a reduction in the number of β-cells and the area of pancreatic islets, which are characteristic of metabolic syndrome. Long-term treatment with metformin and its combination with intranasal insulin partially or fully normalized body weight, abdominal fat, and metabolic and hormonal parameters, with the restorative effect of combination treatment on such parameters as body weight, fat mass, glucose tolerance, and blood glycated hemoglobin levels being more pronounced than with metformin alone. CONCLUSIONS: The results of the study support the use of a combination of metformin and intranasal insulin to normalize metabolic and hormonal parameters in metabolic syndrome induced by breastfeeding disruption in early days of life.

BACKGROUND: Gonadotropin preparations, particularly human chorionic gonadotropin (hCG), are commonly used to induce ovulation and treat reproductive disorders in women, albeit with associated side effects. Low-molecular-weight allosteric agonists of the luteinizing hormone receptor (LHR), such as thieno[2,3-d]pyrimidine derivatives, offer a potential alternative. AIM: This study aims to compare the effects of thieno[2,3-d]pyrimidine TP03 and hCG on ovarian weight, corpus luteum formation, and plasma levels of estradiol, progesterone, and luteinizing hormone in immature female rats pre-treated with Follimag®. It also examines their impact on ovarian gene expression related to LHR and steroidogenesis. MATERIALS AND METHODS: TP03 and hCG were administered 48 h after the Follimag® injection at a dose of 20 mg/kg (i.p.) and 15 IU/rat (s.c.), respectively. Parameters were assessed at 1, 2, 4, 8, 16, and 24 h after TP03 and hCG administration. Plasma hormone levels were measured via ELISA, and ovarian gene expression was analyzed using real-time PCR. RESULTS: TP03 increased ovarian weight, progesterone levels in the blood, and expression of steroidogenic genes encoding the cholesterol-transporting protein StAR and the cytochromes CYP11A1 and CYP17A1. TP03 also stimulated corpus luteum formation (16–24 h after treatment). The temporal dynamics of its stimulating effects were similar to those of hCG, although their magnitude was slightly inferior to those of gonadotropin. TP03-induced decrease in blood estradiol levels and aromatase gene expression in the ovaries was also more moderate. Unlike hCG, which suppressed LHR gene expression 8 h after treatment, TP03 maintained a high LHR gene expression, preserving ovarian sensitivity to endogenous luteinizing hormone. CONCLUSIONS: TP03 exhibits potential as an ovulation inducer with milder stimulating effects on ovarian steroidogenesis than hCG, which reduces the risks of developing ovarian hyperstimulation syndrome and resistance to gonadotropins.

The search for natural biologically active substances that have a neuroprotective effect on cerebral ischemia-reperfusion is one of the urgent problems of modern neuroscience and medicine. Intranasally administered insulin (IAI) has a pronounced restorative effect on various neurodegenerative diseases, but the mechanisms of its action and therapeutic effects in cerebral ischemia have not been studied well, including in type 2 diabetes mellitus (DM2), which increases the risk of cerebrovascular dysfunction. The aim of the work was to study the effect of IAI on metabolic parameters and inflammatory factors in male rats with DM2 subjected to the two-vessel ischemia and prolonged forebrain reperfusion, in comparison with non-diabetic animals. A long-term high-fat diet with an injection of a low dose of streptozotocin (25 mg/kg) to rats was used to induce DM2, and a model of the global forebrain two-vessel ischemia induced by occlusion of both common carotids with prolonged reperfusion (IR) for 7 days was used to study cerebral ischemia. Two hours after the end of ischemia, rats were treated with IAI at a dose of 0.5 or 2.0 IU/rat, after which the drug was administered in the same doses daily for 7 subsequent days. It was found that IAI prevents body weight loss in both nondiabetic and diabetic rats that underwent IR, and also increases the total cholesterol level and the proportion of epididymal fat in rats without DM2 after IR. In DM2 rats that underwent IR, IAI in the explored doses reduces the level of postprandial glucose and insulin content in the blood, which indicates an improvement of glucose tolerance, and also reduces the levels of inflammatory factors in the blood – C-reactive protein (at a dose of 0.5 IU/rat/day) and tumor necrosis factor-α (in a dose of 2 IU/rat/day), which reveals its anti-inflammatory potential. Thus, the course treatment with IAI after induction of cerebral ischemia followed by reperfusion leads to an improvement of metabolic parameters and weakens inflammatory reactions in rats with DM2, which may be in demand in the correction of ischemic stroke in patients with DM2.

The regulatory effects of luteinizing hormone (LH) and chorionic gonadotropin (CG) are realized through the activation of the G-protein coupled LH/CG receptor (LH/CG-R). The result of this is the activation of various types of G proteins, which leads to stimulation (Gs) or inhibition (Gi) of the cAMP-dependent pathway and stimulation of calcium signaling (Gq/11, Gi), and the recruitment of β-arrestins, which prevent G protein signaling through receptor internalization and downregulation, but can also activate the mitogen-activated protein kinase cascade. Despite a certain similarity in the effects of LH and CG, there are differences between them both in efficiency and in the pattern of regulation of LH/CG-R. This is a consequence of differences in the affinity of LH and CG to the orthosteric site of the receptor, as well as differences at the level of allosteric regulation of the receptor, which is due to the presence of a C-terminal extension in the β-subunit of CG, including sites for O-glycosylation, and the variability of N-glycosylation of α- and β-subunits of gonadotropins. Moreover, the number of N-glycans, the degree of their branching and charge differ, which leads to different efficiency of activation of intracellular cascades, affecting the physiological response of the reproductive system to gonadotropins. Of great importance is the formation of homodi(oligo)meric complexes of LH/CG-R and its heterocomplexes with the follicle-stimulating hormone receptor, where protomers allosterically influence the efficiency of LH/CG-R activation and the bias of signal transduction. Taking into account the large number of allosteric sites in LH/CG-R, the development of low-molecular allosteric regulators is underway, including agonists based on thieno[2,3-d]-pyrimidine and peptides derived from the cytoplasmic loops of LH/CG-R. These regulators can become prototypes of drugs for correcting the functions of the reproductive system. This review is devoted to the analysis of data on the similarities and differences in the signaling and physiological effects of gonadotropins with LH activity, the role of allosteric mechanisms in this, and the prospects for creating allosteric regulators of LH/CG-R.

The so-called cafeteria diet (CD), rich in saturated fats and light fast-digesting carbohydrates, leads to obesity and is a risk factor for type 2 diabetes. Metformin (MF) is often used to correct diet-induced obesity, but in some patients, it elicits serious side effects, which requires dose reduction, including through its co-application with drugs potentiating MF effects. Intranasally administered insulin (INI), which per se has a restorative potential in the treatment of metabolic disorders, is a candidate for the role of such a drug. This work was aimed to study the efficacy of a 3-week combined course of MF (100 mg/kg/day, perorally) and INI (1.5 or 6.0 IU/kg/day) to correct metabolic and hormonal disorders in male rats with CD-induced obesity (CDIO). It was shown that in CDIO rats, the MF + INI combination normalized body weight and abdominal fat, as well as restored glucose homeostasis, lipid metabolism, basal and glucose-stimulated insulin and leptin levels. Compared to MF monotherapy, a combined course of MF + INI application more effectively restored insulin sensitivity, as assessed by a decrease in the insulin resistance index, and normalized glucose tolerance, as assessed by a decrease in AUC0–120, the integrated area under glucose concentration curves in the glucose tolerance test. The combination of MF with INI at a dose of 1.5 IU/kg/day normalized thyroidal status, disturbed in CDIO, while the combination of MF with INI at a dose of 6 IU/kg/day exacerbated the hypothyroid state, mainly due to hyperactivation of thyroid-stimulating hormone secretion and the development of thyroid resistance to this hormone. Thus, a combined course of MF with relatively low-dose INI, which has no negative effects on the thyroid axis, appears promising for correcting metabolic and hormonal indices in CDIO, including functional restoration of the thyroid system.