摘要: It is known that social stress could alter oxytocin (OT) and arginine-vasopressin (AVP) expression in specific regions of brains which regulate the aggressive behavior of small rodents, but the effects of density-induced social stress are still unknown. Brandt's voles (Lasiopodomys brandtii) are small herbivores in the grassland of China, but the underlying neurological mechanism of population regulation is still unknown. We tested the effects of housing density of Brandt's voles on OT/AVP system with physical contact (allowing aggression) and without physical contact (not allowing aggression) under laboratory conditions. Then, we tested the effects of paired-aggression (no density effect) of Brandt's voles on OT/AVP system under laboratory conditions. We hypothesized that high density would increase aggression among animals which would then increase AVP but reduce OT in brains of animals. Our results showed that high housing density induced more aggressive behavior. We found high-density-induced social stress (with or without physical contact) and direct aggression significantly increased expression of mRNA and protein of AVP and its receptor, but decreased expression of mRNA and protein of OT and its receptor in specific brain regions of voles. The results suggest that density-dependent change of OT/AVP systems may play a significant role in the population regulation of small rodents by altering density-dependent aggressive behavior.

摘要: As an organophosphorus compound that frequently detected in water samples, triphenyl phosphate (TPhP) has been showed to have multiple toxicological effects on aquatic species. However, no attention has been paid to its potential impact on non-model amphibian species. Here, tadpoles of the Zhenhai brown frog (Rana zhenhaiensis) were exposed to different concentrations of TPhP (0, 0.02 and 0.1 mg/L) throughout the developmental period to assess physiological and metabolic impacts of TPhP exposure on amphibian larvae. After 30-day TPhP exposure, the developmental stage of tadpoles from the high-concentration treatment appeared to be more advanced than that from the other two treatments, but other measured traits (including body size, tail length and liver weight) did not differ among treatments. Metabolite profiles in tadpole livers based on liquid chromatography-mass spectrometry (LC-MS) revealed a distinct metabolic disorder in exposed animals. Specifically, significant changes in various hepatic amino acids (such as glutamine, glutamate, valine and leucine) were observed. Overall, our results indicated that chronic TPhP exposure potentially caused developmental and hepatic physiological changes in R. zhenhaiensis tadpoles, although its impact on tadpole growth appeared to be minor.