Neural control of reproduction in reptiles

Abstract

Reptiles display considerable diversity in reproductive behavior, making them great models to study the neuroendocrine control of reproductive behavior. Many reptile species are seasonally breeding, such that they become reproductively active during their breeding season and regress to a nonreproductive state during their nonbreeding season, with this transition often prompted by environmental cues. In this review, we will focus on summarizing the neural and neuroendocrine mechanisms controlling reproductive behavior. Three major areas of the brain are involved in reproductive behavior: the preoptic area (POA), amygdala, and ventromedial hypothalamus (VMH). The POA and VMH are sexually dimorphic areas, regulating behaviors in males and females respectively, and all three areas display seasonal plasticity. Lesions to these areas disrupt the onset and maintenance of reproductive behaviors, but the exact roles of these regions vary between sexes and species. Different hormones influence these regions to elicit seasonal transitions. Circulating testosterone (T) and estradiol (E2) peak during the breeding season and their influence on reproduction is well‐documented across vertebrates. The conversion of T into E2 and 5α‐dihydrotestosterone can also affect behavior. Melatonin and corticosterone have generally inhibitory effects on reproductive behavior, while serotonin and other neurohormones seem to stimulate it. In general, there is relatively little information on the neuroendocrine control of reproduction in reptiles compared to other vertebrate groups. This review highlights areas that should be considered for future areas of research.

Parental brain through time: The origin and development of the neural circuit of mammalian parenting

“…The MPOA or POA is a key brain site for male sexual behaviors in all vertebrate groups that have been tested, including teleosts, amphibians, and reptiles (Figure 4E). 117,171,172,204,[205][206] The existing evidence, though limited, also suggests the role of the MPOA in basal vertebrate parental care as seen in mammals. 94 In mammals, the studies by Dulac and colleagues, followed by ours, have demonstrated that the MPOA neuronal populations activated during male mating and paternal care overlap significantly (Fig.…”