Functional development of sex accessory organs of the male rat. Use of oestradiol benzoate to identify the neonatal period as critical for development of normal protein-synthetic and secretory capabilities

Abstract

Functional development of the sex accessory tissues was studied in the male rat. Three potentially crucial developmental periods (neonatal, prepubertal and pubertal) were examined, and then the functional integrity of the accessory tissues was investigated in the adult, when the animals would have been expected to display normal function. Four accessory tissues (the seminal vesicles, ventral prostate and caput and cauda epididymides) were used because of their different embryological origins and responses to androgens in the adult. Synthesis and secretion of previously characterized tissue-specific androgen-dependent proteins were taken as indicators of normal function. Development was perturbed by using oestradiol benzoate, since this was known to affect gross development of the seminal vesicles and ventral prostate when given to neonatal rats. Treatment during the first 5 days after birth severely restricted development of the seminal vesicles and ventral prostate. Protein secreted by the former was only 1% of the normal amount, and in many cases several major secretory proteins were essentially missing. Prostatic protein secretion was less than 20% of normal, but all the major proteins were detectable. In both tissues overall protein synthesis per cell was quantitatively normal, but the proportion devoted to specific major secretory proteins was markedly depressed, i.e. the response is differential. In contrast, treatment during the prepubertal period was without noticeable effects. Development of the seminal vesicles and prostate was somewhat inhibited by treatment at puberty, but these changes were minor compared with those after neonatal exposure to oestradiol benzoate. No effects on epididymal protein synthesis or secretory proteins were observed, and epididymal weight and DNA content were only moderately decreased regardless of when oestradiol benzoate was administered during sexual maturation. Hence the neonatal period is not so critical for epididymal development. The substantial changes elicited by oestrogen treatment during neonatal life in seminal-vesicle and prostatic protein synthesis and secretion were compared with those evoked in sexually mature males by either oestrogen treatment or castration. Both these latter treatments resulted in a general decrease in seminal-vesicle protein synthesis and secretion, but the marked differential effects on major proteins after neonatal exposure were absent. Castration did, however, evoke a differential prostatic response, but this was not seen after oestrogen treatment of adults.