Behaviour 2019
Neuronal morphology related to vasotosin and isotocin of gobiid fish with different mating systems
Kazuya Fukuda1, Takao Mukuda2, Masahumi Kawaguchi3, Naoyuki Yamamoto1. 1Laboratory of Fish Biology, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya-shi, Aichi-pref, Japan; 2Department of Anatomy, Faculty of Medicine, Tottori University, Yonago-shi, Tottori-pref., Japan; 3Department of Anatomy and Neuroscience, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Toyama-shi, Toyama-pref., Japan

Diversification of mating systems is known in many vertebrate lineages. Recently, we suggested that the neuropeptides vasotocin and isotocin (teleostean homologs of vasopressin and oxytocin) contribute to the establishment of different mating system in phylogenetically closely related monogamous (Trimma marinae) and polygamous (Trimma caudomaculatum) gobiid fish. However, differences in neuronal substrates related to vasotocin and isotocin remain unknown, which are responsible for the difference of mating system. In this study, we compared the morphology, number, and projections of fibers of vasotocin and isotocin producing neurons between the two species. We found that vasotocin neurons of monogamous females heavily distribute within the dorsal region of the preoptic area compared to polygamous female. Next, we compared the distribution pattern of the receptor for vasotocin (V1a1, V1a2), isotocin and dopamine (D2a: teleostean homologs of mammalian D2-type dopamine receptor), by means of in situ hybridization. We will discuss on the interspecific differences in neuronal substrates related to vasotocin and isotocin underlying the variation of mating systems in these species.