Neonatal sex reversal of the brain and the urinary excretion of sex dependent proteins (SDP) in the rat.

In contrast to females adult male rats excrete a variety of low molecular weight sex dependent urinary proteins (SDP). Electrophoretic separation of these proteins yields at least 8 protein bands which are arranged in typical patterns. The present study was performed to investigate the effect of sexual differentiation, which can be influenced by neonatal hormone treatment, on production and excretion of the individual SDP-bands (I-VIII). Two major groups of rats were studied: one group was neonatally treated with testosterone propionate (TP, females) or cyproterone acetate (males). Another group of rats with or without neonatal TP-treatment were gonadectomized in adulthood and subsequently implanted with TP. The results demonstrated that SDP excretion is mainly related to the circulating plasma testosterone levels. The sexual differentiation of the brain, however, influences the quantity of SDP excreted which is especially evident for bands I and II. Neonatal cyproterone had influence on these two bands only. The results demonstrate that the hormonal mechanisms regulating the excretion of SDP varies in respect to the different protein bands. The functional role of sexual brain differentiation on the excretion of SDP and the detailed mechanisms by which the brain may control this excretion remain to be determined.