Anxyolitic effects of testosterone is not induced by aromatization of estradiol

YUNES R.; BOULIN F.; CABRERA R.

Córdoba

Congreso; Sociedad Argentina de Farmacología Experimental (SAFE); 2006

Anxyolitic effects of testosterone is not induced by aromatization of estradiol. Yunes R, Boulin F, Cabrera R.  IMBECU (CONICET), and Area de Farmacología, Facultad de Ciencias Médicas, Universidad Nacional de Cuyo, 5500 Mendoza ? Argentina. ryunes@fcm.uncu.edu.ar   It has been reported that in males testosterone (T) and its metabolites dihydrotestosterone and 3a-androstanediol exhibit all of them anxiolytic properties. However, and since T is also usually aromatized to estradiol (E2), it has not been ruled out the possibility of E2 being at least partially responsible for the aforementioned effect. Adult Sprague-Dawley male rats (n = 8 animal/group) were used. Anxiety (total time spent exploring the open arm: TOA) and locomotion activity (number of total arm entries: TLA) were tested on an elevated plus-maze. Our results showed that TOA was significantly shorter in castrated animals, irrespectively of being treated or not with E2 10 or 25 µg  (p < 0.05, Student´s t test). On the other hand, castrated males treated with T did not show any change in their anxiety levels regarding control animals. Also, it is worth mentioning that by comparing validated measures we can assert that the anxiolytic effect is not a mere ?unspecific? increase of motility. Summarizing, in this report and by using intact and castrated male rats, with or without E2 or T replacement, we could conclude that the anxiolytic effect is not due to E2 but to T and, eventually its non aromatizable metabolites. Whether or not T action is linked to a direct effect of the steroid on its intracellular receptor and/or via modulation of GABAA or glutamate receptors remains to be established.