Effect of synthetic luteinizing hormone – releasing hormone (LH–RH) on ovulation and pituitary cytology of the goldfish Carassius auratus

Abstract

Synthetic luteinizing hormone – releasing hormone (LH–RH) induces ovulation and stimulates release of secretory granules from the pituitary gonadotrophs of goldfish kept at 12 ± 1 °C, a temperature at which ovulation does not occur in control fish. Gonadal development is stimulated at doses too low to induce ovulation. Relatively high doses were required to induce ovulation; this may be related to the low experimental temperatures, although several other possibilities are discussed. Intracranial injections appeared to be only slightly more effective than intraperitoneal injections. A single type of gonadotroph containing two types of granules was identified at the ultrastructural level. Only the small, electron-dense granules are released after injection of synthetic LH–RH; the role of the large, less electron-dense granules is uncertain.

Profiles of plasma gonadotropin and 17β-estradiol in the common carp, Cyprinus carpio L., as related to spawning induced by hypophysation or LH-RH treatment

“…Giving doses 600 to 1 500 times higher than ours induced ovulation in the ayu (Hirose and Hishida, 1974), the goldfish (Lam et al, 1975(Lam et al, , 1976, different species of carp (Conference on Application of Hormones to economic Fish, 1975), the Japanese medaka (Chan, 1977), the plaice and the goby (Aida et al, 1978).…”

“…The most empirically efficient procedure is to give two injections, the first containing 10 p. 100 of the total dose and the second 90 p. 100 (Antalfi and T61 9 , 1975). This classical so-called « hypophysation » has been tentatively replaced by LH-RH injections which induce ovarian maturation (Sokolowska, Popek and Bieniarz, 1978), or even ovulation (Conference on Application of Hormones to Economic Fish, 1975), in carp and ovulation in the ayu (Hirose and lshida, 1974), goldfish (Lam et al, 1975(Lam et al, , 1976, plaice and goby (Aida et al, 1978 Weil, 1973 ;Weil, Breton and Reinaud, 1975 ;Crim, Peter and Billard, 1976) and salmonids (Crim and Cluett, 1974 ;Weil et al, 1978). Exogenous gonadotropin injections increase estradiol production during vitellogenesis in trout and at the end of the cycle in carp (Fostier, Breton and Jalabert, 1979), but at that final stage in trout, Van Bohemen and Lambert (1979) did not detect aromatization enzymes in the ovary.…”

Influence of gonadotropic hormone-releasing hormone analog (GnRH-A) on plasma sex steroid profiles and milt production in male winter flounder, Pseudopleuronectes americanus (Walbaum)

“…Indeed, increasing the temperature of acclimation of carp from 25-30°C increases their plasma androgen levels and the GSI (Kime and Manning 1986). Dose-dependent effects of GnRH-A on plasma gonadotropin or sex steroids were not observed in goldfish (Lam et al 1976;Peter 1980) and in coho salmon (Van Der Kraak et al 1983. In male flounder, an examination of 3 different doses of GnRH-A ranging from 2-200 g/kg produced remarkably similar T and 11 -KT steroid profiles with no evidence of GnRH-A dose-response effects.…”

A histological study of the hypophysial‐gonadal system during sexual maturation and spawning in the milkfish, Chanos chanos (Forskal)

“…Changes in these cells have been demonstrated during sexual maturation, and in response to gonadectomy (Ball & Baker, 1969;Nagahama, 1973;de Vlaming, 1974;Percy et al, 1975;Suarez, 1976;Haider, 1978;Ueda & Takahashi, 1980) or hormones (Ball & Baker, 1969;Leatherland, 1969;Yamamoto & Nagahama, 1973;Lam et al, 1976;Pandey et al, 1977;Chiba et al, 1978;Ueda & Takahashi, 1980).…”