[Characterization and biological activity of new 4-oxo-1,4-dihydrocinnoline-based inhibitors of the tyrosine phosphatase PTP1B and TCPTP]. / Kharakteristika i biologicheskaia aktivnost' novykh ingibitorov tirozinfosfataz PTP1B i TCPTP na osnove 4-okso-1,4-digidrotsinnolina.

Functional disorders in obesity are largely due to a decrease in tissue sensitivity to insulin and leptin. One of the ways to restore it is inhibition of protein phosphotyrosine phosphatase 1B (PTP1B) and T-cell protein phosphotyrosine phosphatase (TCPTP), negative regulators of the insulin and leptin signaling. Despite progress in the development of inhibitors of these phosphatases, commercial preparations based on them have not been developed yet, and the mechanisms of action are poorly understood. The aim of the work was to study the effect of new derivatives of 4-oxo-1,4-dihydrocinnoline (PI04, PI06, PI07) on the activity of PTP1B and TCPTP, as well as to study the effect of their five-day administration (i.p., 10 mg/kg/day) to Wistar rats with diet-induced obesity on body weight and fat, metabolic and hormonal parameters, and gene expression of phosphatase and insulin and leptin receptors in the liver. It has been shown that PI04 is a mild, low selective inhibitor of both phosphatases (PTP1B, IC50=3.42(2.60-4.51) µM; TCPTP, IC50=4.16(3.49-4.95) µM), while PI06 and PI07 preferentially inhibit PTP1B (IC50=3.55 (2.63-4.78) µM) and TCPTP (IC50=1.45(1.18-1.78) µM), respectively. PI04 significantly reduced food intake, body weight and fat, attenuated hyperglycemia, normalized glucose tolerance, basal and glucose-stimulated levels of insulin and leptin, and insulin resistance index. Despite the anorexigenic effect, PI06 and PI07 were less effective, having little effect on glucose homeostasis and insulin sensitivity. PI04 significantly increased the expression of the PTP1B and TCPTP genes and decreased the expression of the insulin and leptin receptor genes. PI06 and PI07 had little effect on these indicators. Thus, PI04, the inhibitor of PTP1B and TCPTP phosphatases, restored metabolic and hormonal parameters in obese rats with greater efficiency than inhibitors of PTP1B (PI06) and TCPTP (PI07). This indicates the prospect of creating mixed PTP1B/TCPTP inhibitors for correction of metabolic disorders.

[Restriction of breastfeeding in the early postnatal period leads to metabolic and endocrine disorders in eighteen-month-old male rats.]

Breastfeeding deficiency in the early postnatal period can lead to metabolic and hormonal disorders in adulthood. However, there are no studies on the effect of starvation in early ontogeny on metabolic and hormonal parameters in aging animals. The effect of such starvation on the functions of the endocrine system has not been practically studied. The aim of this work was to study how interruption of lactation in lactating female rats (19-21 days of postnatal development of rat pups) affects metabolic parameters, glucose tolerance, insulin sensitivity, and hormonal status of the gonadal and thyroid axes in their offspring, 18-month-old male rats. Inhibition of lactation was induced by treating female rats with bromocriptine (10 mg/kg/day). It has been shown that aging male rats with partial deprivation of breastfeeding have characteristic signs of the metabolic syndrome, such as the increased body weight and adipose tissue, impaired glucose tolerance, insulin resistance, and hyperleptinemia. They have reduced levels of testosterone and thyroid hormones, increased levels of thyroid-stimulating hormone, reduced steroidogenic response to gonadoliberin and a decrease in thyroliberin stimulating effect on thyroxine levels. Thus, short-term deprivation of breastfeeding caused by bromocriptine-induced inhibition of lactation in lactating females leads to the development of metabolic syndrome and hormonal dysregulation of the reproductive and thyroid systems in 18-month-old male rats.

[Influence of intranasally administered insulin on metabolic and hormonal parameters in adult male rats, impaired due to three-day fasting in the early postnatal period]. / Vliianie intranazal'no vvodimogo insulina na metabolicheskie i gormonal'nye pokazateli u vzroslykh samtsov krys, narushennye vsledstvie trekhdnevnogo golodaniia v rannem postnatal'nom periode.

Temporary cessation or restriction of breastfeeding can lead to metabolic disorders in adulthood. However, data on the effect of fasting in the early postnatal period on the functions of the endocrine system in adulthood are rare and contradictory. Approaches for the correction of metabolic and hormonal disorders caused by premature cessation of breastfeeding have not been developed yet. The aim of the work was to study the metabolic and hormonal parameters and changes in the hormonal status of the gonadal and thyroid systems in 10-month-old male rats with interruption of breastfeeding on days P19-P21, as well as to evaluate the restorative effect on them of four weeks of treatment with intranasal insulin (II) administered in the postnatal period (P28-P55) or in adulthood (P183-P210). Lactation interruption has been induced by treatment of lactating females with bromocriptine (10 mg/day/rat, P19-P21). Male rats with temporary cessation of breastfeeding developed characteristic signs of the metabolic syndrome (obesity, dyslipidemia, impaired glucose tolerance, hyperleptinemia), decreased levels of testosterone and thyroid hormones (fT4, tT3) and weakened the synthesis of testosterone and thyroxine, stimulated respectively by GnRH and thyroliberin. This was due to a decrease in the sensitivity of the testes to luteinizing hormone (LH) and the thyroid gland to thyroid-stimulating hormone (TSH). Treatment with II in early ontogenesis reduced body weight and fat, improved lipid profile, sensitivity to insulin, leptin, LH and TSH, restored the levels of testosterone and thyroid hormones and their stimulation by releasing factors. Treatment with II in adulthood normalized the levels of testosterone, thyroid hormones, their stimulation by releasing factors, but had a little effect on metabolic and hormonal parameters. The obtained data point to a wide range of metabolic and hormonal disorders in adult male rats with the "neonatal" model of metabolic syndrome and to the effectiveness of various strategies for their correction using long-term II treatment.

Development of Low-Molecular-Weight Allosteric Agonist of Thyroid-Stimulating Hormone Receptor with Thyroidogenic Activity.

To normalize the thyroid status in hypothyroidism caused by resistance to thyroid-stimulating hormone (TSH), low-molecular-weight allosteric agonists of TSH receptor can be used. A new compound ethyl-2-(4-(4-(5-amino-6-(tert-butylcarbamoyl)-2-(methylthio)thieno[2,3-d]-pyrimidine-4-yl)phenyl)-1H-1,2,3-triazol-1-yl) acetate (TPY3m), which stimulated the production of thyroxine when administered to rats (25 mg/kg, i.p.) and also increased the expression of thyroidogenic genes in the cultured FRTL-5 thyrocytes (30 µM) and the rat thyroid gland. The in vitro and in vivo treatment with TPY3m did not lead to a decrease in the expression of the TSH receptor gene in thyrocytes, restoring it under the conditions of receptor hyperactivation by the hormone. This determines the retaining and, in some cases, potentiation of the thyroidogenic effects of TSH (FRTL-5) or thyroliberin (rats) when they are coadministered with TPY3m. TPY3m is a prototype drug for correcting thyroid system functions in subclinical hypothyroidism.

The Study of Biological Activity of a New Thieno[2,3-D]-Pyrimidine-Based Neutral Antagonist of Thyrotropin Receptor.

The development of low-molecular-weight antagonists of thyroid-stimulating hormone (TSH) receptor is a promising trend in the treatment of autoimmune hyperthyroidism. We studied the effect of thieno[2,3-d]-pyrimidine derivative TPY1 on TSH-stimulated synthesis of thyroid hormones in the culture of FRTL-5 thyrocytes and on thyroliberin-stimulated production of thyroid hormones in rat blood. Preincubation of FRTL-5 cells with TPY1 suppressed the stimulatory effect of TSH on the synthesis of thyroxine and triiodothyronine. Intraperitoneal injection of TPY1 in a dose of 25 mg/kg reduced thyroliberin-stimulated levels of thyroid hormones in the blood and inhibited the expression of genes encoding thyroid peroxidase, thyroglobulin, and Na+/I- cotransporter responsible for thyroxine synthesis. In the absence of thyroliberin stimulation, TPY1 did not affect the levels of thyroid hormones and expression of thyroidogenesis genes. Thus, a new TPY1 antagonist of TSH receptor can be a prototype of a drug for the treatment of autoimmune hyperthyroidism.

Comparative Study of the Restoring Effect of Metformin, Gonadotropin, and Allosteric Agonist of Luteinizing Hormone Receptor on Spermatogenesis in Male Rats with Streptozotocin-Induced Type 2 Diabetes Mellitus.

We compared the effectiveness of human chorionic gonadotropin (hCG; 5 days, 20 IU/rat/day), allosteric luteinizing hormone receptor agonist TP04 (5 days, 20 mg/kg/day), and metformin (28 days, 120 mg/kg/day) in restoring spermatogenesis in male rats with type 2 diabetes mellitus. hCG and TP04 increased the levels of testosterone and expression of the steroidogenic protein StAR, the number of spermatogenic cells, thickness of the seminal epithelium, and the number and motility of mature sperm that were reduced in diabetic rats, though they did not reduce the number of defective spermatozoa. Metformin had a weak effect on steroidogenesis, but was not inferior to luteinizing hormone receptor agonist by its restorative effect on spermatogenesis and also reduced the number of defective forms of spermatozoa. Thus, the spermatogenesis-restoring effect of metformin and luteinizing hormone receptor agonist in type 2 diabetes mellitus are comparable, despite different mechanisms of action.

Stimulation of Ovulation in Immature Female Rats Using Orthosteric and Allosteric Luteinizing Hormone Receptor Agonists.

Human chorionic gonadotropin (hCG) and luteinizing hormone (LH) are widely used for the treatment of reproductive disorders and for controlled ovulation induction, but their use is limited by side effects. Allosteric agonists of the LH/hCG receptor, including thieno[2,3-d]thienopyrimidine TP03 developed by us, can become an alternative. TP03 (50 mg/rat, i.p.) when administered to immature female rats treated 48 h before with Follimag has been shown to increase progesterone levels (maximum 8 h post-treatment) and induce ovulation, as indicated by the appearance at 24 h corpus luteum (8.6 ± 0.5 per ovary). In terms of its activity, TP03 is comparable to hCG, although it acts more moderately. In the ovaries, unlike hCG, TP03 does not lead to an increase in the expression of vascular endothelial growth factor, which can cause ovarian hyperstimulation syndrome. Thus, TP03 is a promising drug as an ovulation inducer and ovarian steroidogenesis stimulator.

The Effect of Low-Molecular-Weight Allosteric Agonist of Luteinizing Hormone Receptor on Functional State of the Testes in Aging and Diabetic Rats.

Human chorionic gonadotropin that is widely used for improving spermatogenesis. The effect of chorionic gonadotropin is mediated through luteinizing hormone receptor. Treatment with gonadotropin is associated with undesirable effects due to hyperactivation of testosterone production and luteinizing hormone receptor desensitization. A promising alternative could be low-molecular-weight agonists of luteinizing hormone receptors, but their effects on spermatogenesis have not been investigated. Here we analyzed the effect of a thieno[2,3-d]pyrimidines (TP), 4-((3-(5-amino-6-(tert-butylcarbamoyl)-2-(methylthio)thieno [2,3-d]pyrimidine-4-yl) phenyl)carbamoyl)pyridine 1-oxide (TP22), an allosteric agonist of luteinizing hormone receptors, on the seminiferous tubules and spermatogenic cells in 4- and 18-month-old male rats and in animals with diabetes mellitus. TP22 and gonadotropin were administered in daily doses of 15 mg/kg and 20 U/rat for 5 days. Blood testosterone level, morphology of the seminiferous tubules, and the number of germ cells in them were estimated. Being comparable by the efficiency to gonadotropin, TP22 increased the testosterone level in all the studied groups of rats and restored epithelium thickness in the seminiferous tubules and the number of spermatogonia and pachytenic spermatocytes that are reduced in aging and diabetes, but, unlike gonadotropin, did not suppress the expression of luteinizing hormone receptor. The efficacy of TP22 as a stimulator of testicular spermatogenesis has been demonstrated both under normal conditions and in age-related and diabetes-associated reproductive dysfunctions.

Normalization of Testicular Steroidogenesis and Spermatogenesis in Male Rats with Type 2 Diabetes Mellitus under the Conditions of Metformin Therapy.

One of the complications of type 2 diabetes mellitus in men is steroidogenic and spermatogenic dysfunctions. There is evidence of a restoring effect of the antidiabetic drug metformin on them. We studied the effect of MF therapy (4 weeks, 200 mg/kg/day) on the hormonal parameters of the gonad axis and on the morphological characteristics of epididymal spermatozoa in male rats with a severe form of T2DM caused by a high-fat diet and a low-dose streptozotocin. It has been shown that MF therapy, along with the restoration of the metabolic parameters, normalizes the plasma levels of testosterone and leptin and the content of testosterone, its precursors, leptin and its receptors in the testes, and also increases sperm motility, which is reduced in T2DM. This is the result of both the systemic action of MF and its direct effect on testicular cells.

New Thieno-[2,3-d]pyrimidine-Based Functional Antagonist for the Receptor of Thyroid Stimulating Hormone.

Thyroid stimulating hormone (TSH) receptor antagonists are required for the treatment of TSH-dependent tumors and Graves disease. We developed the compound 5-amino-N-(tert-butyl)-4-(4-iodophenyl)-2-(methylthio)thieno[2,3-d]pyrimidine-6-carboxamide (TP48) and showed that it reduces the TSH-stimulated adenylate cyclase activity in rat thyroid membranes. Pretreatment of rats with compound TP48 (ip, 40 mg/kg) reduced the increase in the levels of total and free thyroxin in blood and the increase in the expression of thyroglobulin and D2 deiodinase genes in the thyroid gland, which are responsible for the synthesis of thyroid hormones, which were caused by intranasal administration of thyroliberin to animals (300 µg/kg). These data indicate that compound TP48 is a functional antagonist of the TSH receptor and can be used to correct the thyroid status in hyperthyroidism.

Restoration of ß-Adrenergic Signaling and Activity of Akt-Kinase and AMP-Activated Protein Kinase with Metformin in the Myocardium of Diabetic Rats.

We studied the effect of metformin (100 and 200 mg/kg/day, 4 weeks) on the adenylyl cyclasestimulating effects of ß-agonists and relaxin in the myocardial membranes and on activities of Akt-kinase, an effector component of insulin signaling, and AMP-activated protein kinase (AMPK), a cellular energy sensor, in the myocardium of rats with type 2 diabetes mellitus induced by high-fat diet and streptozotocin. Metformin normalized the ratio of adenylyl cyclase effects of ß1/2- and ß3-agonists in the myocardial membranes, that is reduced in DM2, and restored phosphorylation of Akt-kinase by Ser473 and AMPK by Thr172 in the myocardium of diabetic rats. The effect of metformin in a dose of 200 mg/kg/day was more pronounced. Thus, the cardioprotective effect of metformin is due to its ability to restore the adrenergic and insulin regulation in cardiomyocytes and their energy status.

Intranasal Administration of Insulin and Gangliosides Improves Spatial Memory in Rats with Neonatal Type 2 Diabetes Mellitus.

We analyzed the effects of intranasal administration of insulin (0.48 U/rat) and gangliosides (6 mg/kg) on spatial memory in rats with the neonatal model of the type 2 diabetes mellitus. The development of diabetes was verified by the glucose tolerance test. Insulin and gangliosides improved training and reversal training in diabetic rats in a modified version of Morris water maze test and reduced the time of finding the hidden platform. High effectiveness of intranasal administration of gangliosides to animals for the normalization of cognitive functions was shown for the first time. The effects of insulin and gangliosides were similar during training, but during reversal training, gangliosides were more effective. At the same time, intranasally administered insulin, unlike gangliosides, partially normalized glucose tolerance in rats with type 2 diabetes mellitus.

[The effect of high-dose metformin on the metabolic parameters and functional state of the liver of agouti-mice with the melanocortin obesity.]

In recent years, the effectiveness of high-dose metformin (MF) to treat the endocrine and oncological diseases has been shown. However, the use of high-dose MF may be associated with the lactic acidosis and the liver dysfunctions. The aim of the work was to study the effect of long-term (10 days) oral administration of a relatively high dose of MF (600 mg/kg per day) into yellow C57Bl/6J (Ay/a) Agouti line mice with the melanocortin type obesity on the liver function, which was evaluated by the morphology of hepatocytes and the severity of steatosis, the expression of the inflammatory and apoptotic factors of and the activity of aminotransferases, as well as on the plasma lactate level in the animals. In Agouti line mice, MF (600 mg/kg per day) caused a decrease in the body and fat weight, led to the reduced hyperglycemia, hyperinsulinemia and hyperleptinemia, and restored the sensitivity to glucose and insulin. At the same time, in the liver of Agouti line mice treated with MF, the small-drop and large-drop fatty degeneration and the hydropic degeneration were attenuated, and the expression of pro-inflammatory IL-1ß and pro-apoptotic Bax protein and the Bax/Bcl-2 ratio did not differ from the control C57Bl/6J (a/a) mice. In the blood of Agouti line mice treated with MF, the activity of alanine aminotransferase was normalized, and the lactate levels was increased, but to a moderate degree. It was concluded that the high-dose MF did not induce the lactic acidosis in Agouti line mice, and at the same time it restored the liver functions impaired in the melanocortin obesity. This allows us to consider the use of the high doses of MF as one of the possible ways to treat obesity and metabolic disorders that are associated with the hepatic steatosis.

Intranasal Administration of Proinsulin C-Peptide Enhances the Stimulating Effect of Insulin on Insulin System Activity in the Hypothalamus of Diabetic Rats.

In type 1 diabetes mellitus, the levels of insulin and C-peptide decrease at the periphery and in CNS. C-peptide potentiates the regulatory effects of insulin. We studied the effects of single and repeated (over 7 days) individual and combined nasal administration of C-peptide (10 µg/day) and insulin (20 µg/day) on activity of Akt kinase and kinase-3ß-glycogen synthase (GSK3ß), the components of 3-phosphoinositide pathway, in the hypothalamus of intact rats and rats with mild streptozotocin-induced type 1 diabetes mellitus. Phosphorylation of Akt kinase at Thr308 and Ser473 (stimulation) and GSK3ß at Ser9 (inhibition) was evaluated. In diabetes, phosphorylation of Akt kinase and, to a lesser extent, GSK3ß, is reduced. A single injection of insulin or C-peptide and insulin increased this process. Long-term combined treatment with C-peptide and insulin normalized activity of Akt kinase and GSK3ß in diabetic rats, treatment with insulin alone produced less pronounced effect; monotherapy with C-peptide was ineffective. Intranasal co-administration of C-peptide and insulin effectively stimulates the insulin system in the hypothalamus that is weakened at diabetes mellitus type 1, which can be used in the treatment of this disease.

[The effect of different types of bariatric surgery on the metabolic and hormonal parameters in rats with decompensed form of type 2 diabetes mellitus.]

Currently, one of the approaches to correct metabolic disorders in the type 2 diabetes mellitus (DM2) with obesity are bariatric surgery (BS), including sleeve gastrectomy (SG), gastric bypass (GB) and ileal transposition (IT). However, their effectiveness and impact on the hypothalamic signaling and hormonal status in severe forms of DM2 without obesity remain little studied. The aim of the work was to study the effect of IT, SG and GB on the insulin, leptin, ghrelin and glucagon-like peptide-1 (GLP-1) levels in the blood and on the expression of the genes encoding the main components of the hypothalamic signaling systems in rats with decompensated form of DM2, which was induced by a high-fat diet (3 months) and a single low dose of streptozotocin (25 mg/kg, 2 months after the start of the diet). In diabetic rats, a significantly expressed hyperglycemia, an impaired glucose tolerance, a decrease in glucose-stimulated GLP-1 level, a slight decrease in the insulin and leptin levels and an slight increase in ghrelin level were detected. In the hypothalamus, the expression of the genes encoding GLP-1 receptor, orexigenic agouti-related peptide (AgRP), as well as phosphotyrosine phosphatase 1B and SOCS3, the negative regulators of the leptin and insulin pathways was increased. In diabetic rats, the IT reduced the glucose levels 120 minutes after glucose load, increased the basal and glucose-stimulated GLP-1 levels, normalized the gene expression for phosphotyrosine phosphatase 1B, SOCS3, AgRP and GLP-1 receptor, which indicates the restoration of the hypothalamic signaling responsible for the control of energy metabolism and insulin sensitivity. In the case of SG and GB, an improvement in the glucose tolerance was found, and in the case of SG, an increase in the basal and glucose-stimulated GLP-1 levels was shown. However, no significant effect on the expression of the hypothalamic genes in SG and GB was found. Thus, IT is the most effective of all studied BS in the treatment of severe forms of DM2 without obesity.

Prospects of intranasal insulin for correction of cognitive impairments, in particular those associated with diabetes mellitus.

Despite the well-studied effect of insulin in peripheral tissues, its role in functioning of the central nervous system is much less understood. The effects of insulin in the brain are extremely diverse: insulin plays an important role in neuron growth and differentiation, affects higher cognitive functions (in particular, the formation of long-term memory), and also has a neuroprotective effect. Both peripheral and central insulin resistance as well as absolute insulin deficiency impairs the functional activity of neurons and neurogenesis. Several studies have investigated intranasal administration of insulin as a potential way for correction of these disorders. The review presents data on abnormalities of the insulin signaling system in the brain in diabetes mellitus, which is accompanied by cognitive dysfunction of varying severity and is associated with the development of neurodegenerative disorders, including Alzheimer's disease. We analyzed the results of studies on the use of intranasal insulin in animal models with diabetes mellitus, healthy volunteers, and patients with cognitive impairments.

Conservation of Steroidogenic Effect of the Low-Molecular-Weight Agonist of Luteinizing Hormone Receptor in the Course of Its Long-Term Administration to Male Rats.

Abstract-It was shown that the thienopyrimidine derivative TP03, a low-molecular-weight agonist of the luteinizing hormone receptor (LHR), during the treatment of male rats for 7 days steadily increased the production of testosterone (T), whose elevated level was retained for 7 days, and increased the expression of the gene for LHR, which indicates the maintenance of the sensitivity of Leydig cells to gonadotropins. At the same time, the steroidogenic effect of human chorionic gonadotropin (hCG), which significantly increased the T level on the first day of administration, was further weakened, which was accompanied by a decrease in the expression of the gene for LHR in the testes, indicating the development of resistance of Leydig cells to hCG. Along with this, in the case of hCG administration, a compensatory increase in the expression of genes of the steroidogenic enzymes, such as cytochrome P450scc and dehydrogenase 3ß-HSD, was shown in the testes, while in the case of TP03 administration this effect was absent.

[Features of the changes in lipid peroxidation and activity of Na+/K+-ATPase in the brain of the aged rats in the conditions of two-vessel cerebral ischemia/reperfusion.]

The success of preclinical neuroprotection studies depends on the model used in animal research. The methodological approaches developed on young animals and widely used for modeling cerebral ischemia/reperfusion injury may not be so effective or not suitable for its modeling on senescent animals, which usage is recommended for preclinical trials. The aim of this study was to investigate the age-related features on the effect of brain reperfusion with different duration (1 and 3 h) after 2-vessel forebrain ischemia on the level of lipid peroxidation (LPO) products and on the activity of Na+/K+-ATPase in the cerebral cortex of rats aged 22-24 months. We found a later accumulation of LPO products (3 h instead of 1 h after blood recirculation), specifically triene conjugates and Schiff bases, and a decrease in the activity of Na+/K+-ATPase in the cerebral cortex of aged rats compared to young animals. The data obtained reveal the difference in the molecular and physiological mechanisms of the development of disorders in the brain during ischemia/reperfusion in aged and young animals. The revealed differences in these mechanisms should be consider in developing and testing compounds, which will be further used for the treatment of elderly patients with stroke and ischemic brain damage.

[Perspectives of application of intranasally administered insulin for correction of metabolic and hormonal disorders in diabetes mellitus and metabolic syndrome].

In recent years, the possibility of using intranasally administered insulin to treat Alzheimers disease and other cognitive disorders has been widely studied. At the same time, the possibility of its use in the treatment of diabetes mellitus is practically not investigated, which is due to the insufficient study of the molecular mechanisms of its action on the hormonal and metabolic status of the organism. The review discusses literature data and the results of our own research on the role of insulin in the central regulation of energy homeostasis, as well as on the experience of using intranasally administered insulin to correct eating disorders and metabolic and hormonal dysfunctions developing under conditions of experimental diabetes mellitus and metabolic syndrome. In studies involving healthy volunteers, various effects of intranasally administered insulin were shown, including effects on cognitive function, eating behavior and weight loss, and the gender specificity of its action was found. In the course of numerous studies of intranasally administered insulin in animal models of diabetes mellitus, not only stabilization of carbohydrate homeostasis was shown, but also a positive effect in the form of restoration of the functional activity of insulin signaling pathways in the hypothalamus and other parts of the brain. We have presented and analyzed data on the systemic effects of intranasally administered insulin in rodents with experimental models of diabetes mellitus, as well as in healthy individuals.

[The effect of Metformin on metabolic parameters and hypothalamic signaling systems in rats with obesity induced by a high-carbohydrate/high-fat diet.]

Metformin (MF), a first-line drug in the treatment of diabetes mellitus, has been used in the recent years to treat obesity. Its therapeutic effect is due not only to the influence on the peripheral tissues, but also on the hypothalamus, which controls food behavior and energy metabolism. The aim was to study the effect of MF therapy (200 mg/kg/day, 8 weeks) in rats with obesity caused by a high-carbohydrate/high-fat diet on the metabolic and hormonal parameters and functional state of the hypothalamic signaling systems. The MF treatment of obese rats (the group ObM) normalized the food behavior, reduced the body and fat weight and the glucose, insulin and leptin levels, increased the sensitivity to glucose and insulin, improved the lipid metabolism, and restored the Ser473-phosphorylation of Akt-kinase in the liver. In the hypothalamus, the stimulating adenylyl cyclase (AC) effects of the agonists of type 4 melanocortin receptor and type 1 dopamine receptor were partially restored, the inhibitory AC effect of the agonists of subtype 1B serotonin receptor (5-HT1BR) was increased, which was associated with an increase in Htr1b gene expression, and the stimulating effect of the 5-HT6R-agonist EMD-386088 was normalized. At the same time, the differences in the activity of the leptin and insulin systems and the ratio of anorexigenic and orexigenic factors in the hypothalamus of the rat groups Ob and ObM were insignificant. Thus, MF treatment changes functional activity of the hypothalamic melanocortin, dopamine and serotonin systems in obese rats, which is one of the reasons to decrease their food intake and to restore the metabolic indicators and insulin sensitivity.