To investigate whether the various steroid hormones can modulate the basal and angiotensin II-induced protein kinase C (PKC) activity in the anterior pituitary of the rat, female and male intact and ovariectomized female Wistar rats were treated in vivo with estradiol (E2), progesterone (P), dehydroepiandrostendione, sulfate (DHEA-S), and pregnenolone sulfate (PREG-S). Estradiol caused the increase of basal PKC activity in intact and ovariectomized females, but did not change the enzyme activity in males. In ovariectomized animals the increase of PKC activity was lower than in intact females. Progesterone decreased PKC activity only in intact animals. DHEA-S strongly enhanced activity of PKC in ovariectomized females. Pregnenolone sulfate did not significantly change PKC function of all studied groups. Incubation with AngII enhanced the PKC activity in intact (without steroid treatment) animals of both genders. In females, AngII and estradiol together rise the PKC-stimulated phosphorylation in greater degree than used separately. Treatment with other investigated steroids reduced the effect of AngII. In intact males every examined hormone turned back the stimulatory effect of AngII on PKC activity. These data suggest that gender differences in PKC activity are likely related to hormonal milieu of experimental animals and may depend in part on the basic plasma level of estrogens. (C) 2002 Elsevier Science (USA). All rights reserved.