Effects of pneumadin (PNM) on the adrenal glands. 6. Further studies on the inhibitory effect of PNM on dexamethasone-induced atrophy of the rat adrenal cortex
A. Markowska1, P.G. Andreis2, B. Miskowiak1, G.G. Nussdorfer2 and L.K. Malendowicz1
1Department of Histology and Embryology, School of Medicine, Poznan, Poland and
2Department of Anatomy, University of Padua, Padua, Italy
Offprint requests to: Prof. G.G. Nussdorfer, Department of Anatomy, Via Gabelli 65, 1-35121 Padova, Italy
Summary. Pneumadin (PNM) is a biologically active decapeptide , which has previously been found to enhance rat adrenal growth; the mechanism is indirect and probably involves the stimulation of both argininevasopressin (AVP) and ACfH release. The effects of 2- and 6-day PNM administration on the atrophic adrenal cortices of rats treated for 8 and 12 days, respectively, with daily subcutaneous injections of 15 or 40 g/100 g body weight of dexamethasone (Ox) were investigated. Morphometry showed that PNM counteracted Oxinduced adrenal atrophy, by preventing the decrease in volume and number of the parenchymal cells. PNM rai sed aldosterone and corticosterone production of adrenal quarters from Ox-treated rats, but it did not evoke significant changes in the plasma concentrations of the two hormones. The preventive effect of PNM was only partial and almost exclus ively evident in rats administered the lower dose of Ox. In light of these findings the following conclusions are drawn: (i) PNM is able to partially overcome the Ox-induced inhibition of the rat hypothalamo-pituitary-adrenal axis, probably by stimulating the pituitary release of AVP and ACfH, that in turn enhance adrenocortical growth; (ii) the PNMinduced improvement of the secretory capacity of atrophic adrenocortical cells is not sufficient to raise the blood level of corticosteroid hormones; and (iii) Ox exerts a direct inhibitory action on adrenocortical cells, which is not counteracted by PNM. Histol Histopathol 12, 677-682 (1997)
Key words: Pneumadin, Adrenal cortex, Hypothalamopituitary-adrenal axis, Steroidogenesis, Morphometry,
Rat
DOI: 10.14670/HH-12.677