Abstract
The secretion of gonadotropins (GtH) in goldfish and carp, is stimulated by GtH-releasing hormone (GnRH) and is inhibited by dopamine. Studies with antidopaminergics have demonstrated to be effective in order to stimulate the spermiation and the ovulation in different species of teleosts. The reserpine, a drug that deplets the dopamine, has shown to stimulate the spermiation in the common carp. We report here, the effects of reserpine on the number and volume of gonadotrophic cells of the common carp. Eight injections of reserpine alone, at doses of 0.5, 1.0 or 1.5 mg/ml/kg of body weight and at intervals of 48 hours, caused an increase in the number and volume of gonadotrophic cells. The dose 0.5 mg/ml/kg, presented an increase in the number and volume of gonadotrophic cells of 382% and 123%, respectively, above the control group. The dose 1.0 mg/ml/kg, showed an enhanced number and volume of gonadotrophic cells of 704% and 152%, respectively. With the dose 1.5 mg/ml/kg increase in number (171%) and volume (106%) of gonadotrophic cells was lower. The gonads of the experimental groups had an abundance of advanced states of spermatogenesis. Our results show that eight intraperitoneal injections of reserpine were responsible for an increase in gonadodrophic cell, number and volume.
Highlights
It has been established that secretion of gonadotropin (GtH) in goldfish (Chang and Peter 1983) and carp (Sokolowska et al 1988), is stimulated by GtH-releasing hormone (GnRH) and is inhibited by dopamine, throughout mechanisms which involve D2 receptors (Chang et al 1993)
In order to understand the influence of this antidopaminergic, we investigated the effects of three different doses of reserpine, on gonadotrophic cells, in the pituitary gland of male carps
The experimental groups showed an increase in the number of gonadotrophic cells; Group 5 presented a mean of 2 506 and Group 4, 1 361 cells per gland
Summary
It has been established that secretion of gonadotropin (GtH) in goldfish (Chang and Peter 1983) and carp (Sokolowska et al 1988), is stimulated by GtH-releasing hormone (GnRH) and is inhibited by dopamine, throughout mechanisms which involve D2 receptors (Chang et al 1993). Intraperitoneal injections of dopamine antagonists potentiated the GtH release response and increased the frequency of ovulation or spermiation, induced in goldfish (Chang and Peter 1983, Chang et al 1984a, Sokolowska et al 1985), common carp (Billard et al 1983) and silver carp (Lin et al 1985). Reserpine is a substance which depletes catecholamines stores, potentiating the effects of LHRH-A on serum gonadotropin levels, ovulation and spermiation, in common carp (Sokolowska et al 1988) and in loach (Lin et al 1986, Sokolowska et al 1988). In order to understand the influence of this antidopaminergic, we investigated the effects of three different doses of reserpine, on gonadotrophic cells, in the pituitary gland of male carps
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