The ACTH-interrenal axis in the freshwater stickleback,Gasterosteus aculeatus form leiurus

Summary The ACTH-interrenal axis of the freshwater stickleback has been examined with the fish in a variety of physiological conditions. A morphometric analysis of ACTH cell ultrastructure in spring animals revealed that the only change from the winter condition was a significant decrease in the amount of perinuclear RER. The interrenal gland responded to metopirone treatment by an increase in both nuclear and cell size, although only a high dose of metopirone could degranulate the ACTH cells. Morphometry of the ACTH cells from metopirone-treated animals showed a significant increase in the amount of RER and a significant decrease in the number of free ribosomes and secretory granules, compared with control animals maintained in freshwater. Such ultrastructural changes may be expected of a cell that is stimulated to increase its secretion of polypeptide hormone. The ACTH-interrenal axis also responded to 70% seawater, as this treatment increased the interrenal cell and nuclear sizes.     

Effects of metopirone on the structure of endocrine glands in the male lizard,Cnemidophorus l. lemniscatus (L.)

Summary Adrenals, pituitary glands, thyroids, testes and kidneys of metopirone-treated and control male lizards were studied by light microscopy. Pituitary-interrenal axis: A great hypertrophy and hyperplasia of the interrenal cells and the pituitary corticotrophs were found in the experimental group. Pituitary-thyroid axis: Metopirone-treated animals showed a moderate hypertrophy and degranulation of pituitary thyrotrophs, and signs of uneven hyperactivity of the thyroid. Pituitary-testicular axis: By effect of metopirone, a marked regression of pituitary interstitiotrophs and a virtual disappearance of the testicular interstitial gland took place. The second portion of the kidney sexual segments appeared degranulated as in castrated animals. The pituitary folliculotrophs and the seminiferous epithelium of the testis did not show alterations.     

Corticotropin-like immunoreactivity in the brain of intact,hypophysectomized, cortisol- and metopirone-treated eels

Summary An ACTH-like peptidergic system was demonstrated in the brain of three teleost species by immunocytochemistry. In order to investigate the origin of brain ACTH and factors modulating its synthesis, similar techniques were applied to the brain of eels (1) submitted to hypothysectomy in order to suppress pituitary ACTH and plasma cortisol, (2) injected with cortisol to inhibit pituitary ACTH synthesis and release, and (3) injected with metopirone to block cortisol synthesis and stimulate ACTH synthesis and release. Hypophysectomized eels showed a normal distribution of immunoreactive perikarya in the ventral hypothalamus and fibers in the brain, suggesting that brain ACTH does not arise from the pituitary. In cortisol-treated eels immunostaining was markedly reduced in brain perikarya and pituitary corticotropes, suggesting a reduced synthesis. In metopirone-injected eels, one third of the animals showed an increased immunostaining in perikarya and a dense network of immunoreactive fibers, suggesting that ACTH synthesis was increased. Brain ACTH was not affected in other animals. Pituitary corticotropes were rapidly degranulated. Responses of ACTH in the brain and pituitary occur independently when cortisol synthesis is inhibited. These responses are compared to those of the corticotropin-releasing factor system in the same eels.     

Einfluß von synthetischen Glucocorticoiden und von Metopiron auf ketosteroidhaltige Zellen des postnatalen Kaninchenthymus

Zusammenfassung Nachdem durch die NAHD-Reaktion (Camber, 1949) Ketosteroide in den granulierten Zellen des Kaninchenthymus dargestellt werden konnten (Möllmann et al., 1973), wurde der Ketosteroidgehalt des Thymus an Hand des zahlenmäßigen Verhaltens der Camber-positiven Zellen in der Postnatalzeit (1.–30. Tag), nach Glucocorticoidapplikation sowie nach Metopirongabe überprüft. Die bei der Geburt nur vereinzelt auftretenden granulierten Zellen vermehrten sich stetig bis zu einem Maximum am 9. postnatalen Tag, um daraufhin wieder abzunehmen. Ein Vergleich dieser Befunde mit dem relativen Thymusgwicht ergab eine nahezu gegensinnige Korrelation. Nach Verabreichung von Glucocorticoiden von Geburt an zeigten die Thymi von Kaninchen, die nicht am Wasting-Syndrom verstarben, eine deutliche Zunahme der Camber-positiven Zellen, wiederum gegenläufig zum relativen Thymusgewicht. Hingegen führte die mehrtägige Applikation von Metopiron zu keinen Veränderungen der Zahl und des Aussehens dieser Zellen.Die vorliegenden Befunde sowie die Ergebnisse anderer Autoren (s. Literatur) lassen eine Abstammung der Ketosteroide des Thymus aus dem Glucocorticoidmetabolismus vermuten.

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Influence of synthetic glucocorticoids and of metopirone on ketosteroid-containing cells of the postnatal rabbit thymus

Summary After postnatal (1–30 days) administration of glucocorticoids or of metopirone to rabbits the ketosteroid content of the thymus was evaluated from the number of Camber-positive cells, using the NAHD-reaction of Camber (1949), which appears in granular cells of the rabbit thymus (Möllmann et al., 1973). Granular cells are sparse at birth and steadily increase in number, attaining a maximum on day 9, after which they decrease numerically. A comparison of these findings with the relative thymus weight shows an almost inverse correlation. After giving glucocorticoids from birth those thymi of rabbits which did not perish from wasting-syndrome showed a distinct increase in Camber-positive cells, again inversely to the relative thymic weight. On the other hand, administration of metopirone over a period of several days produced no change in either number or appearance of these cells.The above findings, combined with observations in the literature, lead to the assumption that ketosteroids of the rabbit thymus are derived from the glucocorticoid metabolism.