EFFECTS OF ACUTE AND CHRONIC IMMOBILIZATION STRESS ON RAT LEYDIG-CELLSTEROIDOGENESIS

In rats, acute immobilization (IMO) stress (2 h) induced a fall in the serum androgen concentrations (T + DHT) without detectable changes in serum luteinizing hormone (LH) values. In vitro studies, using a susp ension of Leydig cells from adult rat testis, demonstrated that acute stress inhibited conversion of progesterone (P) or 17hydroxyprogestero ne (17OHP) to T while conversion of androstendione (Delta,A) was not a ffected. Acute IMO reduced activity of 3 beta-hydroxysteroid dehydroge nase (3 beta-HSD) and decreased basal and hCG-stimulated progesterone and androgen production. Chronic IMO stress (2 h daily for 10 days) in duced a decrease in serum androgen level with decline in serum LH valu es. In vitro, hCG-stimulated progesterone and androgen production by s uspension of Leydig cells, as well as conversion of P and 17OHP to T w ere not significantly altered. Our data demonstrates that acute IMO st ress impaired testicular steroidogenesis primarily at the testicular l evel (decreasing the activity of certain enzymes), while chronic IMO s tress exerts the effect mainly on the hypothalamic-pituitary axis; red uced serum LH levels elicit a decrease in serum androgen levels. Copyr ight (C) 1996 Elsevier Science Ltd.