High cholesterol is known to negatively affect uterine contractility in conditions. The aim of the present study was to reveal the effect of hypercholesterolemia on spontaneous and oxytocin-induced uterine contractility in late pregnant mouse uterus. Female Swiss albino mice were fed with high cholesterol (HC) diet (0.5% sodium cholate, 1.25% cholesterol and 15% fat) for 6 weeks and then throughout the gestation period after mating. On day 19 of gestation, serum cholesterol level was increased more than 3-fold while triglycerides level was reduced in HC diet-fed animals as compared to control animals fed with a standard diet. In tension experiments, neither the mean integral tension of spontaneous contractility nor the response to CaCl in high K-depolarized tissues was altered, but the oxytocin-induced concentration-dependent contractile response in uterine strips was attenuated in hypercholesterolemic mice as compared to control. Similarly, hypercholesterolemia dampened concentration-dependent uterine contractions elicited by a GNAQ protein activator, toxin. However, it had no effect on endogenous oxytocin level either in plasma or in uterine tissue. It also did not affect the prostaglandin release in oxytocin-stimulated tissues. Western blot data showed a significant increase in caveolin-1 and GRK6 proteins but decline in oxytocin receptor, GNAQ and RHOA protein expressions in hypercholesterolemic mouse uterus. The results of the present study suggest that hypercholesterolemia may attenuate the uterotonic action of oxytocin in late pregnancy by causing downregulation of oxytocin receptors and suppressing the signaling efficacy through GNAQ and RHOA proteins.
A study was undertaken to investigate the effect of melatonin supplementation on thyroid hormones (T3, T4) and cortisol in buffalo calves under summer stress. Twelve healthy Murrah buffalo male calves of 6 month to 1 year age group were taken for the study. Buffalo calves were divided into control (CG) and treatment (TG) group. In TG, Melatonin (18mg/50 kg BW) was injected subcutaneously, two times at 1 st and 20 th day. Hormones like T3, T4 and cortisol were estimated by Gamma coat TM (125I) RIA kits. Within and between the groups serum T3 and T4 level did not differ significantly (P>0.05), but higher level of serum T3 and T4 was observed in CG than TG. The significant (P<0.05) difference observed in serum cortisol level between the groups and within CG. In conclusion, melatonin used to have its effect on thyroid hormone response and level of cortisol secretion during summer stress. It decreases T3, T4 and cortisol levels in the animals and helps them to cope with adverse effect of summer stress.
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