author(s)
Vikas G Barsagade

abstract
In fish, neuroendocrine system is the reciprocal crosstalk between the neurotransmitter/neuropeptides and endocrine factors. As in mammals, various neuroendocrine factors in fish are involved to regulate the fish physiology specifically reproduction and development. Dopamine is a key brain regulator that regulates fish reproduction and stress through a conserve neuronal pathway. Sex specific and reproductive stage related expression of dopamine probably is controlled by environmental factors as well as fish endogenous signals. D1 and D2 receptor families mediate the regulatory functions of dopamine neurotransmission, which regulates a range of brain activities. Recent study revealed the nine receptor subtypes of dopaminergic system and D1 receptor family, but not D2 family, is involved in the regulation of sex steroid production. Although dopamine localization and its mechanism appear to be conserved among vertebrates, major physiological differences between vertebrate classes and the diversity of fish, in particular in regard to site of synthesis, role of dopamine receptors, its signaling action and crosstalk with other neuropeptides, suggest the existence of species-specific regulating mechanisms in fishes. Based on the most recent research, this review gives a current update of the dopaminergic system and its mechanism of action within the framework of fish brain.