Delay of Castration Induced Regression in Rat Prostate by Pituitary Homografts

Abstract

Although prolactin has a synergistic effect with testosterone in stimulating growth of the lateral lobe of the rat prostate, the role of prolactin in the absence of testosterone has not been well established. We studied the effect of prolactin on the rate of prostatic regression induced by castration in mature Sprague-Dawley rats. Anterior pituitaries from female rats were transplanted under the renal capsule in all rats. Castration and unilateral nephrectomy were carried out 1 week later. Half of the animals had the normal, non-grafted kidney removed and another half had the kidney bearing the pituitary grafts excised. Rats were sacrificed on days 0, 7, 10 and 14 and 3 lobes of the prostate were dissected separately. The lateral lobe showed a marked decrease in the rate of regression in the pituitary graft-bearing rats. In control animals, the relative weight of the lateral lobe on days 7, 10 and 14 was 38 +/- 2 per cent (mean +/- SE), 33 +/- 2 per cent and 26 +/- 2 per cent of the day 0 value, respectively; the respective relative weight in animals carrying pituitary grafts was 67 +/- 4 per cent, 51 +/- 5 per cent, and 38 +/- 3 per cent of the day 0 value. The difference in the weight of the lateral lobe between the 2 groups was significant on days 7 (p less than 0.001) and 10 (p less than 0.05) and was not significant on day 14. There was no difference in the mean body weight in graft bearing and non-graft bearing animals. Bilateral adrenalectomy at the time of castration did not influence the rate of prostatic regression in either group. Furthermore, pituitaries implanted in rats castrated for 3 weeks had no stimulatory effect of the prostates. These results indicate that increased endogenous prolactin, in the absence of testicular and adrenal secretion, delays the castration-induced regression of the lateral lobe of the prostate of Sprague-Dawley rats.

Maternal exposure to atrazine during lactation suppresses suckling- induced prolactin release and results in prostatitis in the adult offspring

“…Although we saw no differences in the weights of the lateral prostate at 90 or 120 days of age in our other treatment groups, a number of studies have reported a direct PRL stimulation of the growth of the lateral prostate (Kolbusz and Grayhack, 1982;Prins, 1987). in the adult animal.…”

Regional variations in the testicular dependence of prolactin binding and its possible relationship to castration‐induced involution in rat prostate gland

“…After orchidectomy, both ventral and dorsolateral prostatic weights diminished significantly; however, the dorsolateral prostate response to hyperprolactinemia became significantly greater than that of ventral prostate [32]. In the other study, Kolbusz et a1 showed in pituitary-homotransplanted hyperprolactinemic rats that castration-induced involution of lateral lobe was retarded whereas that of ventral and dorsal prostate was not [33]. Accordingly, we observed significantly greater prolactin-binding activity in lateral lobe than in dorsal lobe.…”

Effect of Prolactin on the Population of Epithelial Cells From Ventral Prostate of Intact and Cyproterone Acetate‐Treated Peripubertal Rats: Stereological and Immunohistochemical Study

“…For some authors, PL modulates the size of ventral and dorsal prostate in immature animals (Negro-Vilar et al, 1977). For others, (Kolbusz et al, 1982;Assimos et al, 1984;Smith et al, 1985;Prins, 1987), the influence of PL was more evident on the lateral lobes of mature rats. Nevertheless, still others (Jones et al, 1983;Chang, 1984) found no influence of PL on the prostate volume of adult rats.…”