Secondary alcohol dehydrogenase as a marker of the conversion between progestagens and androgens in the rat testis.

Supraphysiological doses of LHRH-Analogue blocked the C21 to C19 steroid conversion in the mature Wistar rats testis. It was associated with inhibition of the NAD-dependent secondary alcohol-dehydrogenase (A-D II) histochemical reaction in the Leydig cells. Under this condition the treated group exhibited lower testis, seminal vesicle and prostate weights, intratesticular (IT) and plasmatic (PL) increased progesterone (P4) and decreased testosterone (T) concentrations. We also observed a decrease in the IT androstenedione (delta 4) concentration without pregnenolone (P5) change. All these data confirm a chemical castration pointing to a blockade at the level of the P450C21scc (17 alpha-hydroxylase/17-20 desmolase) enzyme complex. After hCG administration there is no difference in sexual gland weights, while steroid's biosynthesis are stimulated and all IT and PL steroid concentrations increase. A-D II showed a lower optical density in the LHRH-A treated groups and no differences in the hCG rats. The hydroxylase or lyase activity of the P450C21scc may change under certain hormonal conditions as occurs in adrenarche, probably due to conformational changes in the active site of the enzyme system since it is encoded by only one gene. We suppose that the secondary alcohol itself and not the coenzyme reacts with the enzyme active site inhibited by the LHRH-A, since the NAD dependent 3 beta, hydroxysteroid-dehydrogenase (3 beta HOST-D) is affected in the opposite sense. This study shows A-D II reaction as a marker of the mediated P450C21scc enzyme complex activity in the rat testis Leydig cells.

Effect of chronic ethanol consumption on the activities of residual small bowel brush-border enzymes after proximal jejunum resection in the rat.

Ethanol consumption has a toxic effect on the epithelium of the small bowel, but enterocyte maturity is very difficult to measure under these circumstances. However, when ethanol intake is combined with enterectomy, enterocyte immaturity is greater, permitting an easier separation of these two effects. In a group of rats (13 male Wistar rats weighing approximately 220 g) fed a liquid diet containing 35% ethanol for 4 weeks after resection of the proximal jejunum, the residual small intestine brush border maltase, sucrase, and lactase activities were similar to those of a pair-fed control group (13 animals). However, alkaline phosphatase activity was decreased in the mucosa and in the enterocyte brush border, probably because of the lower activity of this enzyme in the jejunum-ileum remnant of the alcoholic group.

Ileum brush border alkaline phosphatase activity in an experimental model of chronic alcoholism after small bowel proximal resection in the rat.

Literature reports that chronically ingested ethanol induces changes in the morphology of the small bowel mucous membranes. It has a topical toxic effect on the epithelium of the proximal jejunum and a blood-borne effect on the epithelium of the ileum because its absorption is almost complete in the stomach, duodenum and proximal jejunum. In addition there are also reports showing stimulation of enterocyte proliferation after segmental intestine resection. In this report we compare a group of rats submitted to resection of the proximal jejunum and fed a liquid diet containing 35% of the total calories intake as ethanol for four weeks to its control pair-fed group. In both groups we studied the mucosal alkaline phosphatase (APase) activity by histochemical as well as biochemical methods. We found a decreased APase activity in the homogenate of the intestinal mucous membrane in the alcoholic group and a reduced enzymatic activity in the brush border of the ileum enterocytes, as demonstrated by histochemical qualitative and densitometric assays. The result suggests that this change in APase activity of the brush border may represent enterocyte immaturity induced by long-standing ethanol intake in the remnant ileum after proximal resection.