Pimozide modulates the luteinizing hormone-releasing hormone effect on gonadotrophin release in the African catfish, Clarias lazera

Leeuw, R. de; Resink, J.W.; Rooyakkers, E. J. M.; Goos, H.J.Th.

doi:10.1016/0016-6480(85)90144-3

Cited by 102 publications

(46 citation statements)

References 16 publications

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“…African catfish, C. gariepinus, were reared from eggs to maturity in the laboratory. The breeding techniques and hatchery conditions have been reported by De Leeuw et al (1985). Pieces (5 x 7 cm) of skin taken from the lateral side of the fish from dorsal to ventral were obtained from adult male fish (weight 500 g), cleaned from adipose tissue, and prepared for in vitro incubations to study the bioconversions of steroids and for histological and enzymehistochemical studies.…”

Section: Methodsmentioning

confidence: 99%

The skin of the male African catfish, Clarias gariepinus: A source of steroid glucuronides

Ali¹,

Schoonen²,

Lambert³

et al. 1987

General and Comparative Endocrinology

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Steroid metabolism in the skin of mature male African cattish, Clarias gariepinus, reared in the laboratory, was studied in vitro by tissue incubations with [3H] was transformed mainly to 5-androstene-3P,17@-diol. The products of 17a-hydroxyprogesterone incubations were Sp-pregnane-3a,17a-diol-20-one, SP-pregnane-3a,l7u, 20p-triol, and SP-pregnan-17a-ol-3,20-dione. The major steroids of androstenedione incubations were etiocholanolone, testosterone, and androsterone. Testosterone was converted mainly to etiocholanolone and androstenedione, and only small quantities of 11 P-hydroxytestosterone, 1 l-ketotestosterone, and 1 I-ketoandrostenedione were the metabolites found in 1 l@hydroxyandrostene-dione incubation. These results demonstrated the presence of the enzymes 5a-and 5@re-ductases and 3a-, lll3-, 17p-, and 20P-hydroxysteroid dehydrogenases in the skin. From enzymehistochemical results it appeared that the steroid conversions take place in the epithelial cells. Moreover, the presence of UDP-glucose dehydrogenase, an enzyme involved in the synthesis of glucuronic acid, in these cells indicates the possibility of steroid glucuronide formation. Indeed significant amounts of water-soluble steroid conjugates, particularly SP-dihydrotestosteroneand testosterone-glucuronide, were found in the incubations with androstenedione and testosterone, indicating the presence of the UDP-glucuronosyl transferase in the cattish skin. In the light of these results, a role of the skin of African catfish in the production of semiochemicals having pheromonal properties is discussed. 0 1987 Academic Press, Inc.

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Section: Methodsmentioning

confidence: 99%

The skin of the male African catfish, Clarias gariepinus: A source of steroid glucuronides

Ali¹,

Schoonen²,

Lambert³

et al. 1987

General and Comparative Endocrinology

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“…Intraperitoneal injections with the peptide (0.05 mg/kg body weight) caused the gonadotropin levels in the plasma to increase within 30 min to a maximum at 4-8 h postinjection. Rarely, however, ovulatory levels were reached (De Leeuw et al, 1985a,b, 1987. Chang et al (1984) demonstrated that in the goldfish (Carassius auratus) dopamine acts as a gonadotropin release-inhibiting factor (GRIF) .…”

Section: Regression Of Gonadotropin Releasementioning

confidence: 97%

“…Throughout the year their pituitaries contain large and densely granulated gonadotropes (Peute et al, 1984)) storing large amounts of gonadotropin (De Leeuw et al, 1985a). The gonads of such animals show a continuous cycle with numerous ripe sperm cells and postvitellogenic oocytes at all seasons (Richter and Van Den Hurk, 1982), but without spontaneous spermiation, oocyte maturation and ovulation (Richter et al, 1987b).…”

Section: Reproductive Cyclementioning

confidence: 99%

The African catfish, Clarias gariepinus, a model for the study of reproductive endocrinology in teleosts

Oordt

Goos

1987

Aquaculture

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In their natural habitat African catfish, Clarias gariepinus, show a discontinuous reproductive cycle. This cycle follows changes in the gonadotropic activity of the pituitary. Gonadotropin release has been shown to be under dual hypothalamic control, i.e. a gonadotropin-releasing hormone ( GnRH) and a gonadotropin release-inhibiting factor (GRIF) , which turned out to be dopamine.Gonadal sex hormones influence gonadotropin release by a negative feedback, and a model has been developed to explain their mode of action.Steroid formation has been studied in testes, seminal vesicles and ovaries and correlated with the annual reproductive cycle. Steroid glucuronides, originating from the seminal vesicle, act as male sex pheromones; ovulation seems to be synchronized by female pheromones.Techniques for the induction of ovulation were developed. Only brood&h, reared from eggs to maturity under favourable conditions, show a continuous reproductive cycle and can be induced to produce viable eggs throughout the year.

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“…The breeding techniques and hatchery conditions have been reported by De Leeuw et al (1985). Six mature males lo-12 months of age, weighing about 500 g, were used.…”

Section: Animalsmentioning

confidence: 99%

“…It is known, however, that reduction of the GTH level can be induced by estrogens and aromatizable androgens and not by nonaromatizable androgens (Billard, 1978, De Leeuw et al, 1986 (Chang and Peter, 1983), and the African catfish (De 3 "0 DP Leeuw et al, 1985), catecholamines, espeEstrogen cially dopamine, inhibit the GTH release. A biochemical link between catecholestrogens and catecholamines might be accomplished by the enzyme catechol-O-methyltransferase (COMT), as suggested by Lloyd et al (1978), Knuppen (1981), and Breuer et al (1981).…”

mentioning

confidence: 99%

Estrogen-2-hydroxylase in the brain of the male African catfish, Clarias gariepinus

Timmers

Granneman

Lambert

et al. 1988

General and Comparative Endocrinology

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Estrogen-2-hydroxylase activity, involved in the biosynthesis of catecholestrogens, was localized in the brain of the male African catfish, Clarias gariepinus, by means of a radiometric assay using [2-3H]estradiol as substrate. Fore-and midbrain were divided in 18, SOO+m thick, transverse sections from which small defined areas were punched out and assayed. The estrogen-2-hydroxylase activity was calculated from the release of tritium during hydroxylation, and expressed in femtomole catecholestradiol . milligram-'tissue . hour-'. The enzyme could be demonstrated throughout the brain. A high activity (>350 fmol) was observed in the telencephalon, in particularly the rostra1 part and the area ventralis pars dorsalis; in the diencephalon in the preoptic region, including the magnocellular part of the preoptic nucleus and the rostra1 part of the anterior periventricular nucleus; and in the area tuberalis, including the nucleus lateralis tuberis, the rostra1 part of the nucleus anterior tuberis, the caudal part of the nucleus posterior periventricularis, and in the nucleus recessus posterioris. Also a high activity was detected in the mesencephalic tectum opticum and the dorsolateral part of the torus semicircularis. The ventral mesencephalon showed a moderate (200-350 fmol) to low (<200 fmol) activity, whereas the lowest activity was found in the hindbrain (118 fmol). The significance of the biosynthesis of catecholestrogens in the brain is discussed in light of the negative feedback mechanism of gonadal steroids on gonadotropin release.

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Pimozide modulates the luteinizing hormone-releasing hormone effect on gonadotrophin release in the African catfish, Clarias lazera

Cited by 102 publications

References 16 publications

The skin of the male African catfish, Clarias gariepinus: A source of steroid glucuronides

The skin of the male African catfish, Clarias gariepinus: A source of steroid glucuronides

The African catfish, Clarias gariepinus, a model for the study of reproductive endocrinology in teleosts

Estrogen-2-hydroxylase in the brain of the male African catfish, Clarias gariepinus

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