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SUMMARY
Prolonged aldosterone administration to mice was investigated in relation to liver function. Daily injections of 2 μg. d-aldosterone monoacetate/g. body weight for 60 days adversely affected oxidative phosphorylation of liver mitochondria. The value for the P:O ratio of controls, 3·21, dropped to 2·01, 2·86, 2·45 and 2·79 for mice treated with aldosterone for 20, 30, 50 and 60 days, respectively. The impaired oxidative phosphorylation was neither accompanied by an increase in adenosine triphosphatase activity of liver mitochondria nor by a change in plasma transaminases. Corresponding morphological changes were observed in liver parenchyma starting with hydropic degenerations in early lesions, and single cell necrosis accompanied by mitotic activity (regeneration) in advanced lesions. It seems therefore that hyperaldosteronism might be noxious to liver parenchyma and hepatic function.
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SUMMARY
The relative activities of enzymes participating in the biosynthesis of testosterone via the 4-ene pathway were determined in testicular homogenates of rats acclimatized to a hot environment (33–35 °C, 25–40% relative humidity). Acclimatized animals showed an increase in activity of 17α-hydroxylase, 17,20-lyase and 20α-hydroxysteroid oxidoreductase, whereas the activity of 17β-hydroxysteroid oxidoreductase was markedly decreased. Histological examination of the testes disclosed that neither the germinal epithelium nor the Leydig cells were adversely affected by the increased environmental temperature. The results are discussed in relation to the synthesis and release of the gonadotrophins.
A similar degree of acclimatization, as determined by the comparable decrease in oxygen uptake, was achieved by either of two methods: daily 4 h exposure to a high ambient temperature for 4 weeks or continuous maintenance at 35 °C. The former procedure, however, appeared to be the preferred method for acclimatization of male rats since it did not inhibit growth rate and was free of mortality.
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Two of the most potent cytokines regulating anterior pituitary cell function are leukemia inhibitory factor (LIF) and interleukin (IL)-6, which belong to the cytokine family using the common gp130 signal transducer. Recently, the expression and action of two other members of this family, IL-11 and ciliary neurotrophic factor (CNTF), on different cell lines has also been demonstrated. We studied the expression of the specific receptor subunits for CNTF in mammotropic, non-functioning and somatotropic tumors and the action of CNTF and IL-11 in the regulation of hormone secretion in these and normal pituitary cells. The mRNA for the alpha chain specific for the CNTF receptor was detected by Northern blot in tumors secreting prolactin (PRL) and GH and in non-functioning tumors. We found that both IL-11 and CNTF exerted a similar stimulatory effect on GH mRNA expression in somatotropic monolayer cell cultures from acromegalic tumors, but these cytokines had no significant influence on GH secretion. CNTF stimulates prolactin secretion in lactotropic monolayer cell cultures from patients with prolactinoma. In monolayer cell cultures from normal rat anterior pituitary, IL-11 and CNTF had no significant effect on the release of either GH or PRL, or on GH mRNA. However, when the cells were cultured in aggregate cultures, in which the three-dimensional structure of the cells is reconstituted, both cytokines, in doses at which they had no effect on monolayer cultures, significantly stimulated both PRL and GH secretion. These data show that IL-11 and CNTF may act as regulatory factors in anterior pituitary cells, in which the three-dimensional structure of the gland is of critical importance.
