Efeito da desnutrição protéica pré e pós-natal na espermatogênese de ratos adultos

Abstract

This study investigated the effects of pre- and postnatal protein deficiency on the spermatogenic process in adult rats, associated or not with the increase in testicular temperature. Female Wistar rats received a normoproteic (20% CP, group C) or a hipoproteic (8% CP, group T) diet from five weeks before mating until weaning their pups (three weeks after farrowing). After weaning , all pups were subjected to unilateral cryptorchidic surgery to tie the right testis to the abdominal wall, and were divided into four groups, as follows: a) Group CC: pups from group C mothers that received the normoproteic diet; b) Group CT: pups from group C mothers that received the hipoproteic diet ; c) Group TT: pups from group T mothers that received the hipoproteic diet; and d) Group TC: pups from group T mothers that received the normoproteic diet . The animals were weighed weekly and their feed consumption registered until euthanasia, at 70 days of age, when they were weighed, anesthetized and their testes fixed with a 5% glutaraldehyde in phosphate buffer (0, 1 m-pH 7.4) solution by intravascular perfusion. Testes were removed and fragments included in plastic resin for evaluation under light microscopy. It was verified that protein deficiency, independent of the period in which it occurred, led to a reduction in feed intake which reflected on their body weight gain. The gonadossomatic index was significantly greater in the criptorchidic testicle of the TT group when compared to the other groups showing that pre-natal malnutrition affected more body weight than the testicular weight. The spermatogenesis in the orchidic testicle was interrupted in the spermatids at step 12 only in the animals of the TT group. However, the more advanced germ cells in the criptorchidic testicle were found in the pachytene phase, in all experimental groups. A reduction in the number of spermatogonia, spermatocytes and spermatids was observed in the groups that, at some stage, received the hipoproteic diet and this reduction was more pronounced in the TT group. Moreover, unexpectedly, the raise in the testicular temperature increased the number of Sertoli cells on that group. When assessing the overall efficiency of spermatogenesis, it was found that the capacity to support Sertoli cells was reduced, the loss of germ cells during meiosis was increased and the number of spermatids produced from a spermatogonia type A1 was also reduced in the TT group. These results show that protein malnutrition does not aggravate the effect caused by increase of the testicular temperature. However, in the testis present into the scrotum undernourishment provokes significant changes in several testicular parameters of adult rats, specially in those animals subjected to this deficiency in the pre- and post-natal periods, which resulted in a significant reduction in the daily spermatic production