Abstract
BackgroundAlthough dopamine (DA) exerts modulatory effect on reproduction in the majority of fishes, its role is not clearly understood in viviparous species. The aim of this investigation was to determine the influence of DA antagonist domperidone (DOM) on puberty in the viviparous species Gambusia affinis.ResultsTreatment of 1.5 or 4 mg DOM to 25 days post-hatching (DPH) juveniles for a period of 35 days resulted in dense aggregations of gonadotropin-releasing hormone (GnRH)-immunoreactive fibres in the proximal pars distalis (PPD) region of the pituitary gland in contrast to faintly seen fibres in treatment controls. In the ovary, the follicles belonging to stages I–IV did not differ significantly among different experimental groups. However, stage V (vitellogenic) follicles were completely absent in treatment controls in contrast to their presence in 1.5 or 4 mg DOM-treated fish. Besides, the diameter of stage V follicles was significantly higher in 1.5 mg DOM-treated fish compared with 4 mg DOM-treated fish.ConclusionsThe results suggest that DOM treatment triggers the follicular development and promotes the early onset of puberty, possibly by attenuating the dopaminergic inhibition on GnRH fibres, for the first time in a viviparous species.
Highlights
Dopamine (DA) exerts modulatory effect on reproduction in the majority of fishes, its role is not clearly understood in viviparous species
There was a significant (p < 0.001) increase in the body weight of 1.5 mg DOM-treated fish compared with treatment controls; no such increase was observed in 4 mg DOM-treated fish (Fig. 1a)
In the present study, treatment of 1.5 mg DOM resulted in a significant increase in the mean body weight compared with those of treatment controls, whereas no significant difference was noticed in snout-vent length (SVL) among different experimental groups
Summary
Dopamine (DA) exerts modulatory effect on reproduction in the majority of fishes, its role is not clearly understood in viviparous species. The aim of this investigation was to determine the influence of DA antagonist domperidone (DOM) on puberty in the viviparous species Gambusia affinis. Bhat and Ganesh The Journal of Basic and Applied Zoology (2019) 80:65 viviparous teleost belonging into the family Poeciliidae The placenta in this fish is formed within the follicle and the gestation is intrafollicular (Pandian, 2013). While more studies are required to elucidate the role of DA in fish reproduction, currently, no information is available on the involvement of DA in puberty in viviparous species. The objective of the present investigation is to determine the influence of DA on puberty in G. affinis
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