Effect of photoperiod and 6-methoxybenzoxazolinone (6-MBOA) on the reproduction of male Brandt's voles (Lasiopodomys brandtii).

Plant secondary metabolite 6-methoxybenzoxazolinone (6-MBOA) has been suggested to stimulate animal reproduction. 6-MBOA is detected in Leymus chinensis, a main diet of Brandt's vole (Lasiopodomys brandtii). We have previously reported a stimulatory effect of 6-MBOA on reproduction of male Brandt's voles under a short-day photoperiod. The goal of this study was to investigate the effect of 6-MBOA on reproductive physiology of male Brandt's voles under a long-day photoperiod and examine if 6-MBOA under this photoperiodic regime altered the reproductive status of male Brandt's voles differently than the short-day photoperiod. Under the long-day photoperiod, a high dose of 6-MBOA decreased KiSS-1 mRNA in the arcuate nucleus (ARC), and we also saw a decrease in circulating levels of luteinizing hormone (LH), follicle-stimulating hormone (FSH), and testosterone (T). Steroidogenic acute regulatory protein (StAR) and cytochrome P45011a1 (CYP11a1) in the testes, and relative testis weight also decreased with 6-MBOA administration. Compared to the short-day photoperiod, animals under the long-day photoperiod exhibited increased body weight as well as all other reproductive parameters. Our results showed that 6-MBOA inhibited the reproduction of male Brandt's vole under a long-day photoperiod, a stark contrast from its stimulatory effects under a short-day photoperiod. The paradoxical effects of 6-MBOA suggest it may act as a partial agonist of melatonin. These results provide insight into the complex interactions between environmental factors such as photoperiod and diet in the control of Brandt's vole reproduction.

Effects of dietary tannic acid on the growth, hepatic gene expression, and antioxidant enzyme activity in Brandt's voles (Microtus brandti).

This study was designed to investigate the physiological and biochemical responses of Brandt's voles to the persistent presence of dietary tannic acid. The diet for animals in the experimental group was supplemented with 3% dietary tannic acid for 5weeks. The control group received a commercial lab chow. No significant differences were detected in body weight, organ (heart, kidney, and liver) weights, and organ parameters between animals from two groups. However, voles in the experimental group had significantly higher daily food intake, increased contents of proline and histidine in saliva and feces after protein hydrolysis, and elevated hepatic expression of transferrin than the control. Our results suggested the existence of adaptive strategies developed in Brandt's voles to overcome the adverse effects of dietary tannic acid. (1) Food consumption was increased to satisfy their nutritional demands. (2) The secretion of tannic-acid-binding salivary proteins was promoted. (3) The absorption of iron was enhanced. These alterations contributed to neutralize the negative effects of tannic acid and maintain body mass in animals supplemented with tannic acid. As the result of the consumption of tannic acid, hepatic expression of 3-hydroxy-3-methylglutaryl coenzyme A reductase was significantly decreased, while the overall potential of the antioxidant system, characterized by increased hepatic enzymatic activities of catalase and glutathione peroxidase, was enhanced. Our results also implied the involvement of tannic acid in the regulation of lipid metabolism and oxidative stress in voles.

[The effects of simulated hypoxia on the development of hypothalamic CRF and AVP neurons in postnatal rats].

AIM: To investigate the influence of hypoxia on postnatal developing pattern of hypothalamic corticotropin releasing factor(CRF) and arginine vasopressin (AVP) in male and female neonatal rats. METHODS: The hypoxia was simulated in hypobaric cabin. The content of AVP and CRF was assayed by RIA method. RESULTS: It was showed the female rats had the similar developing process with male rats, either at 2300 m or at 5000 m altitude. When they developed at simulated 5000 m altitude, the content of their hypothalamic CRF was lower than that of control rats on postnatal day 21, while the content of AVP was higher than control on day 21 and 28. CONCLUSION: Maybe the difference of the function between hypothalamic CRF and AVP or/and the incoherence of their developing stage contribute to their particular developing pattern at 5000 m altitude.

[The response of hypothalamic CRF and AVP neurons of neonatal rats to simulated acute hypoxia].

AIM: To investigate the response of hypothalamic corticotropin releasing factor (CRF) and arginine vasopressin (AVP) of adrenalectomized neonatal rats to hypoxia. METHODS: The hypoxia was simulated in hypobaric cabin. The amount of arginine vasopressin (AVP) and corticotropin releasing factor (CRF) was assayed by RIA method. RESULTS: When neonatal rats exposed to acute hypoxia (simulated altitude of 5 000 m and 7 000 m, 24 h), their hypothalamic CRF was not changed in 3 d and 7 d rats, lower than control in 14 d, 21 d and 28 d rats, while hypothalamic AVP had no change in 3 d rats, was lower than control in 14 d and higher in 7 d, 21 d and 28 d rats. The responsive pattern of those two neuropeptides to acute hypoxia changed with the growth of rats. Adrenalectomy reduced the amount of hypothalamic CRF and AVP in 14 d, 21 d and 28 d rats, except AVP in 28 d rats. When adrenalectomized neonates exposed to hypoxia, there was no further change in CRF and AVE, means adrenalectomy not only removed the negative regulation of corticosteroid on CRF and AVE, but also inhibited the normal development of CRF and AVP neurons and thus, their responsive ability to hypoxia.