In vitro techniques for studies on pituitary regulation of rat liver enzymes

Stenberg, Åke; Eneroth, P.; Gustafsson, Jan‐Åke; Skett, Paul

doi:10.1016/0022-4731(77)90269-2

Cited by 3 publications

(1 citation statement)

References 14 publications

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“…Although Gustafsson & Stenberg (1976) have proposed the existence of a novel pituitary factor ('feminotropin') to be involved in the regulation of hepatic steroid metabolism, prolactin and somatotropin have been implicated to be the feminizing factor (Stenberg et al, 1977;Rumbaugh & Colby, 1980 Fig. 5.…”

Section: Discussionmentioning

confidence: 99%

The hypothalamic–hypophyseal–gonadal regulation of hepatic glutathione S-transferases in the rat

Lamartiniere

1981

Biochemical Journal

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Hepatic glutathione S-transferase activities were determined with the substrates 1,2-dichloro-4-nitrobenzene and 1-chloro-2,4-dinitrobenzene. Sexual differentiation of glutathione S-transferase activities is not evident during the prepubertal period, but glutathione conjugation with 1,2-dichloro-4-nitrobenzene is 2-3-fold greater in adult males than in females. Glutathione conjugation with 1-chloro-2,4-dinitrobenzene is slightly higher in adult males than adult females. No change in activity was observed after postpubertal gonadectomy of males or females. Neonatal castration of males results in a significant decrease in glutathione conjugation with 1,2-dichloro-4-nitrobenzene. Hypophysectomy, or hypophysectomy followed by gonadectomy did result in significantly higher glutathione S-transferase activities in both sexes. These increases can be reversed by implanting an adult male or female pituitary or four prepubertal pituitaries under the kidney capsule. Postpubertal sexual differentiation of glutathione S-transferase activities is neither dependent on pituitary sexual differentiation nor pituitary maturation. Prolactin concentrations are inversely related to glutathione S-transferase activities in hypophysectomized rats with or without ectopic pituitaries. Somatotropin exogenously administered to hypophysectomized rats results in decreased glutathione S-transferase activities, whereas prolactin has no effect. Adult male rats treated neonatally with monosodium l-glutamate to induce arcuate nucleus lesions of the hypothalamus have decreased glutathione S-transferase activities towards 1,2-dichloro-4-nitrobenzene and decreased somatotropin concentrations. Our experiments suggests that sexual differentiation of hepatic glutathione S-transferase is a result of a hypothalamic inhibiting factor in the male (absent in the female). This postpubertally expressed inhibiting factor acts on the pituitary to prevent secretion of a pituitary inhibiting factor (autonomously secreted by the female), resulting in higher glutathione S-transferase activities in the adult male than the adult female.

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Section: Discussionmentioning

confidence: 99%

The hypothalamic–hypophyseal–gonadal regulation of hepatic glutathione S-transferases in the rat

Lamartiniere

1981

Biochemical Journal

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Regulation of Prolactin Receptors in Target Cells

Shiu¹,

Friesen²

1981

Receptor Regulation

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Continuous Infusion of Growth Hormone Feminizes Hepatic Steroid Metabolism in the Rat*

et al. 1981

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The metabolism of 4-[4-14C]androstene-3,17-dione was studied in the microsomal fraction of rat livers after continuous administration of human GH (hGH) in Alzet osmotic minipumps under varying conditions. hGH caused a complete feminization of hepatic steroid metabolism (i.e. increased the 5 alpha-reductase and decreased the 6 beta- and 16 alpha-hydroxylase activities) in normal male rats when infused at a rate of 5 microgram/h for 7 days. Hypophysectomy and castration or adrenalectomy and thyroidectomy of male rats did not reduce the feminizing capacity of hGH, indicating that the adrenals and the thyroid gland are not involved in the mediation of the feminizing effect of hGH. The same dose (5 microgram/h for 7 days) of hGH was also able to refeminize the liver steroid metabolism in hypophysectomized-ovariectomized female rats. The effect of the homologous hormones, rat PRL and rat GH on hepatic steroid metabolism was also investigated. Either hormone was infused at a rate of 10 microgram/h for 7 days, a dose which was sufficient to increase the serum level of the hormone in hypophysectomized animals. No feminizing effect was seen after the administration of rat PRL, whereas rat GH caused a partial feminization of hepatic steroid metabolism in hypophysectomized male animals. It is concluded that GH or a hormone related to GH is involved in sexual differentiation of liver steroid metabolism.

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In vitro techniques for studies on pituitary regulation of rat liver enzymes

Cited by 3 publications

References 14 publications

The hypothalamic–hypophyseal–gonadal regulation of hepatic glutathione S-transferases in the rat

The hypothalamic–hypophyseal–gonadal regulation of hepatic glutathione S-transferases in the rat

Regulation of Prolactin Receptors in Target Cells

Continuous Infusion of Growth Hormone Feminizes Hepatic Steroid Metabolism in the Rat*

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