Dopamine receptor agonist bromocriptine restrains the follicular development, hatchling success and puberty in Gambusia affinis

Abstract

Summary The present investigation was conducted to determine the influence of dopamine (DA) receptor agonist bromocriptine (BRO) on reproduction and onset of puberty in the viviparous fish Gambusia affinis. In the first experiment, the mean number of stage I and II follicles (previtellogenic) in 0.8 or 5 mg BRO treated fish did not show significant difference compared to those of experimental controls, whereas the mean number of stage III follicles were significantly lower in 5 mg BRO treated fish compared to experimental controls. However, treatment of 0.8 or 5 mg BRO resulted in significantly lower numbers of stage IV (early vitellogenic) and V (late vitellogenic) follicles compared to those of experimental controls. There was decrease in the percent occurrence of pregnancy and different stages of embryos in BRO treated fish compared with the experimental controls. Concomitant with this, sparsely distributed gonadotropin releasing hormone immunoreactive (GnRH‐ir) fibres were observed in the proximal pars distalis (PPD) region of the pituitary gland in BRO treated fish compared to those of dense accumulations of these fibres in the PPD region of the pituitary gland in experimental controls. In the second experiment, exposure of juveniles (25 DPH) to same doses of BRO for 45 days resulted in complete absence of vitellogenic follicles and presence of few GnRH‐ir fibres in 5 mg BRO treated juvenile in contrast to presence of vitellogenic follicles and dense aggregation of GnRH fibres in treatment controls. Overall, the results of the present investigation suggest that DA affects ovarian follicular and embryonic development and onset of puberty in viviparous species.

Multifactorial control of gonadotropin release for induction of oocyte maturation: Influence of gonadotropin-releasing hormone, gonadotropin release-inhibiting factor and dopamine receptors in the catfish, Heteropneustes fossilis

“…Although this cannot be confirmed from the present study but we speculate that dopamine binds to D2-like receptors in H. fossilis and acts as the gonadotropin release inhibitory factor. This is consistent with the evidence that D2-like receptors (D2, D3 and D4) are involved in the neuroendocrine control of pituitary function in fishes like zebrafish (Fontaine et al, 2013), grey mullet (Nocillado et al, 2007) and gambusia (Bhat and Ganesh, 2019). Dopamine also plays a pivotal role in the neuroendocrine control of LH release in the catfish, similar to evidence from many other fishes, viz.…”

Impact of the Anti-Tuberculosis Drug Rifampicin on the Feeding, Growth and Embryonic Developmental Profile of the Mosquitofish <i>Gambusia affinis</i>

“…Embryos in various stages of development were determined using criteria previously available for this fish 31 . Embryonic development in G. affinis comprises the blastodisc stage, the shield stage, the optic cup stage, the early eyed stage, the mid eyed stage, the late eyed stage, the very late eyed stage, and the mature embryo, which culminates in the birth of juveniles.…”

Domperidone treatment advances onset of puberty in the viviparous mosquitofish Gambusia affinis

“…Five-micron-thick serial paraffin sections of the ovaries were cut using semi-automatic microtome (Leica, Wetzlar, Germany), stained with haematoxylin and eosin and used for the quantification of the follicles at different stages of the development according to the morphology and the size criteria as described earlier (Bhat & Ganesh, 2019). The follicular number and diameter were recorded using Q capture pro 7 image analysis software.…”