Aims Liraglutide is a long-acting glucagon-like peptide 1 (GLP-1) receptor agonist used as an anti-hyperglycemic agent in type 2 diabetes treatment and recently approved for obesity management. Weight loss is attributed to appetite suppression, but therapy may also increase energy expenditure. To further investigate the effect of GLP-1 signaling in thermogenic fat, we assessed adipose tissue oxygen consumption and type 2 deiodinase (D2) activity in mice treated with liraglutide, both basally and after β3-adrenergic treatment. Methods Male C57BL/6J mice were randomly assigned to receive liraglutide (400 μg/kg, n=12) or vehicle (n=12). After 16 days, mice in each group were co-treated with the selective β3-adrenergic agonist CL316,243 (1 mg/kg, n=6) or vehicle (n=6) for 5 days. Adipose tissue depots were assessed for gene and protein expression, oxygen consumption, and D2 activity. Results Liraglutide increased interscapular brown adipose tissue (iBAT) oxygen consumption and enhanced β3-adrenergic-induced oxygen consumption in iBAT and inguinal white adipose tissue (ingWAT). These effects were accompanied by upregulation of UCP-1 protein levels in iBAT and ingWAT. Notably, liraglutide increased D2 activity without significantly upregulating its mRNA levels in iBAT and exhibited additive effects to β3-adrenergic stimulation in inducing D2 activity in ingWAT. Conclusions Liraglutide exhibits additive effects to those of β3-adrenergic stimulation in thermogenic fat and increases D2 activity in BAT, implying that it may activate this adipose tissue depot by increasing intracellular thyroid activation, adding to the currently known mechanisms of GLP-1A-induced weight loss.
Testosterone (T) exerts anabolic actions in body composition and facilitates the metabolic effects of physical exercise in males. T also influences adipose tissue by activating lipolysis, whereas T deficiency is associated with fat mass increase. PURPOSE: To investigate the effect of castration on the mass of different deposits of adipose tissue in male mice submitted to a treadmill interval training (TIT). METHODS: 16 adult (5-6 months) C57BL/6 mice were divided in 2 groups, Sham (n = 8) and gonadectomized (GDX, n = 8). The GDX underwent bilateral orchiectomy while the Sham underwent just a surgical trauma. Then, half of the mice from each group were submitted to a TIT. The mice were subjected to 5-days of treadmill familiarization, at 25° inclination, for 5 min and a speed of 5 m/min. Next, three maximum effort tests were performed, which consisted of 5 min of warming-up at a speed of 6 m/min followed by incremental speed stages of 2 m/min every 2 min, repeated in 48-hour intervals to assess the better distance covered, and maximum speed reached (MSR). Then, the animals were submitted to 8 weeks of a TIT, consisting of an initial warm-up at 5 m/min during 5 min, then 10 bouts of 4 min interspersed with 2 min of active rest (5 m/min). The training starts with an intensity of 55-65% MSR, with an increase of 10% per week reaching the intensity range of 85-95%. After training, the animals were euthanized and the epididymal white adipose tissue (epiWAT), inguinal white adipose tissue (ingWAT) and brown adipose tissue (BAT) were collected and weighed. We compared adipose tissue mass between groups, using One-way ANOVA/Tukey (p ≤ 0.05). RESULTS: We observed a significant reduction in the mass of epiWAT and ingWAT relative to body weight of the Sham-training group, but not of the GDX training group compared with their respective untrained controls. CONCLUSION: This study demonstrates that castration prevents the reduction of visceral and subcutaneous WAT induced by TIT in male mice. Supported by FAP-DF
Abstract Disclosure: N.P. Boris: None. S.A. Pereira: None. G.A. Stamatiades: None. K.N. Hausken: None. H. Kim: None. R.S. Carroll: None. U.B. Kaiser: None. Background: The hypothalamic-pituitary-gonadal (HPG) axis is regulated by pulsatile secretion of hypothalamic GnRH, which acts on anterior pituitary gonadotropes to control synthesis and secretion of LH and FSH. High and low GnRH pulse frequencies preferentially stimulate Lhb and Fshb expression, respectively, through mechanisms that are not completely understood. The mouse Fshb gene promoter contains a half-AP-1/half-cAMP response element (CRE) motif; we have shown previously that this element is bound by CRE-binding protein (Creb) in vitro to increase expression in response to low GnRH pulse frequencies, but is antagonized by inducible cAMP early repressor (Icer) at higher GnRH pulse frequencies, resulting in a lower level of Fshb transcription. In this study, we aimed to identify the role of Icer in gonadotropin regulation in vivo in mice. We hypothesized that gonadotrope-specific deletion of Icer may influence pubertal timing and fertility due to an increase in Fshb expression. Methods and Results: Gonadotrope-specific deletion of Icer (GnrhrGRIC/+/Icerfl/fl; Icer KO) and control (Icerfl/fl) mice were generated, and pubertal and reproductive phenotypes were evaluated. There was no difference in body weight or in pubertal timing, evaluated by age of preputial separation in males and by vaginal opening and first estrus in females. In post-pubertal male mice, neither basal LH and FSH levels nor the LH or FSH response to acute GnRH stimulation were significantly different in Icer KO mice, compared to littermate Icerfl/fl controls. Male Icer KO mice 14 days post-gonadectomy (GDX) had significantly more LH pulses within a three-hour period than controls (Icer KO 5.83 ± 0.4 pulses vs Icerfl/fl 4.66 ± 0.3 pulses; p=0.049), but no differences in basal LH or LH pulse amplitude. Interestingly, serum FSH levels were significantly lower in Icer KO mice compared to Icerfl/fl controls 2 days post-GDX (Icer KO 20.0 ± 1.0 vs Icerfl/fl 26.0 ± 0.8; p=0.003) and 7 days post-GDX (Icer KO 18.0 ± 0.4 vs Icerfl/fl 22.5 ± 0.8, p=0.002). There were no significant differences in pituitary Fshb, Lhb, or Gnrhr mRNA levels between Icer KO and Icerfl/fl control mice 14 days post-GDX. Conclusions: Deletion of Icer from pituitary gonadotropes in mice did not affect body weight or timing of pubertal onset. However, in GDX male mice, LH pulse frequency was increased, whereas the post-GDX increase in serum FSH levels was blunted, in Icer KO mice compared to controls. These findings support a role for Icer in both LH and FSH regulation in vivo and highlight the importance of extending in vitro observations to in vivo models. Presentation: Saturday, June 17, 2023
Summary This study aims to evaluate if a pre-maturation culture (PMC) using cilostamide as a meiotic inhibitor in combination with insulin, transferrin and selenium (ITS) for 8 or 24 h increases in vitro embryo production. To evaluate the effects of PMC on embryo development, cleavage rate, blastocyst rate, embryo size and total cell number were determined. When cilostamide (20 μM) was used in PMC for 8 or 24 h, 98% of oocytes were maintained in germinal vesicles. Although the majority of oocytes resumed meiosis after meiotic arrest, the cleavage and blastocyst rates were lower than the control ( P < 0.05). When the cilostamide concentration was lowered (10 μM) and oocytes were arrested for 8 h, embryo development was improved ( P < 0.05) and was similar ( P > 0.05) to the control. The deleterious effect of 20 μM cilostamide treatment for 24 h on a PMC was confirmed by lower cumulus cell viability, determined by trypan blue staining, in that group compared with the other groups. A lower concentration (10 μM) and shorter exposure time (8 h) minimized that effect but did not improve embryo production. More studies should be performed to determine the best concentration and the arresting period to increase oocyte competence and embryo development.
Climatic variables can trigger physiological, biochemical, haematological and hormonal alterations that influence the maintenance of homeothermy and can affect production and productivity in sheep. Different mechanisms are responsible for tolerance to heat stress (HS) including coat and skin colour, body size, fat distribution, physiological reactions and not just coat type (hair/wool). This review looks at physical, physiological, molecular and genetic aspects of heat tolerance in sheep and how they affect hair and wool sheep. We propose that it is the adaptation to hot environments and not the type of coat (wool/hair) itself that determines the capacity of the resistance of the animal to HS, due to modifications in essential pathways such as energy metabolism, physiological responses and body size. When studied in similar environments, commercial wool breeds tend to show higher heat stress, but hair breeds tend not to differ from wool breeds that are adapted to hot environments.
Nonylphenol (NP) is the predominant environmental biodegradation product of NP ethoxylates and is widely use in detergents, plastic products and paints. It is an endocrine disrupter found to compete with 17β‐estradiol for the binding site of estrogen receptor, due to their structural similarity. More recently, it was also identified as an environmental obesogenic, both in cell culture and in vivo. Acute exposure to NP has been found to induce the expression of adipogenesis and lipogenesis‐related genes in adipose tissue. Additionally, perinatal exposure to different concentrations of NP has resulted in increased body mass and adiposity in male and female offspring. However, the obesogenic potential of long‐term exposure to NP outside the perinatal period has not been investigated. Objective To investigate the effects of chronic exposure to NP on body weight, adiposity and glucose homeostasis in female C57BL/6 mice. Methods Female C57BL/6 mice were fed a high‐fat diet (HFD, 60% kcal as fat) from the 5 th to 20 th week of age. The animals were randomly divided into five groups (n=6) and treated with vehicle (drinking water) or NP 0.5 mg/kg/d or 2.5 mg/kg/d for 16 weeks (5 th to 20 th wk) or for 6 weeks (14 th to 20 th wk) in drinking water. Weight, weight gain, food and water consumption were measured. Two different white adipose tissue (WAT‐retroperitoneal and perigonadal) and one interscapular brown adipose tissue (BAT) depots were weighed. Glucose homeostasis was assessed by fasting glucose levels, glucose tolerance test (GTT), and insulin tolerance test (ITT). Results There was a slight, but nonsignificant trend towards increased body weight and weight gain in response to NP treatment at doses of 0.5 mg/kg/d for 6 or 16 weeks and 2.5 mg/kg/d for 16 weeks when compared to vehicle. On the other hand, mice treated with NP 2.5 mg/kg/d for 6 weeks showed a trend towards decreased body weight. Treatment with NP did not affect energy intake, but increased water consumption when compared to vehicle. Fasting glucose levels at the 20 th week were nonsignificantly decreased by NP treatment (0.5 mg/kg/d, 6 wk). However, there were no changes in glucose tolerance or insulin sensitivity. Visceral WAT, subcutaneous WAT and BAT mass remained unchanged in response to treatment with NF. Conclusions Our findings suggest long‐term exposure of female mice to environmentally relevant NP concentrations, outside of the developmental period, does not affect glucose homeostasis or adiposity. Support or Funding Information CNPq/CAPES/FAPDF
Studies in humans and mice support a role for Makorin RING finger protein 3 (MKRN3) as an inhibitor of gonadotropin-releasing hormone (GnRH) secretion prepubertally, and its loss of function is the most common genetic cause of central precocious puberty in humans. Studies have shown that the gonads can synthesize neuropeptides and express MKRN3/Mkrn3 mRNA. Therefore, we aimed to investigate the spatiotemporal expression pattern of Mkrn3 in gonads during sexual development, and its potential regulation in the functional testicular compartments by gonadotropins. Mkrn3 mRNA was detected in testes and ovaries of wild-type mice at all ages evaluated, with a sexually dimorphic expression pattern between male and female gonads. Mkrn3 expression was highest peripubertally in the testes, whereas it was lower peripubertally than prepubertally in the ovaries. Mkrn3 is expressed primarily in the interstitial compartment of the testes but was also detected at low levels in the seminiferous tubules. In vitro studies demonstrated that Mkrn3 mRNA levels increased in human chorionic gonadotropin (hCG)-treated Leydig cell primary cultures. Acute administration of a GnRH agonist in adult mice increased Mkrn3 expression in testes, whereas inhibition of the hypothalamic-pituitary-gonadal axis by chronic administration of GnRH agonist had the opposite effect. Finally, we found that hCG increased Mkrn3 mRNA levels in a dose-dependent manner. Taken together, our developmental expression analyses, in vitro and in vivo studies show that Mkrn3 is expressed in the testes, predominantly in the interstitial compartment, and that Mkrn3 expression increases after puberty and is responsive to luteinizing hormone/hCG stimulation.
Sex steroid hormones are major effectors of the sexual dimorphism in mammals and are suposed to differently impact cardiometabolic responses to exercise training. Testosterone is related to the development of strength and muscle mass while estrogen is believed to associate with endurance capacity. Sex differences on cardiorespiratory fitness (CRF) response to interval training (IT) deserve further evaluation, specially in animal models. PURPOSE: To compare the CRF response to a treadmill interval training protocol in mice of both sexes. METHODS: 26 adult (3-4 months old) C57BL/6 mice were evaluated (14 fem / 12 males). Firstly, all animals were subjected to a 10-day treadmill familiarization step within 2 weeks, 5 days/week, at 25° inclination, having both session duration and speed progressively increased from 5 to 10 min and 5 to 10 m/min), respectively. After familiarization, 3 maximum exercise tests were carried out on a 48 h-interval to assess the average maximum distance and speed reached (MSR). The test consisted of 5-min warm up at 6 m/min followed by incremental speed stages of 2 m/min every 2 min, at 25° inclination. Tests were considered maximum when mice were unable to, or refused to run even with mechanical stimulation. After basal CRF evaluation, mice were separated into exercise (EG–9 fem/7 mal) and control groups (CG-5 fem/9 mal). The EG trained for 4 weeks, starting with a warm-up at 5 m/min and a subsequent IT of 10 bouts of 4 min running at moderate intensity (55–65% MSR), interspersed by 2 min active rest (5 m/min), always at 25°. After training, CRF was assessed as in the pre-training period. Groups were compared before and after training protocol. RESULTS: The IT significantly increased CRF (p < 0.01) in EG. Remarkably, females showed a higher CRF increase (56.3%) than males (43.1%) (p < 0.01). CRF remained unchanged in CGs of both sexes (p > 0.05). CONCLUSION: The 4-week of IT was effective to improve CRF in both sexes but females had a significantly higher improvement compared to males. Our findings suggest that sex differences must be taken into account in animal studies once sex hormonal and/or behavioral differences may significantly impact the training responses in mice. Supported by Fundação de Apoio à Pesquisa do Distrito Federal - FAP DF:0193.001571/2017; KAB is a PIBIC student – FAP DF: 00193.001467/2016.
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