Regulação da proliferação pós-natal das células de Sertoli em ratos

AUTOR(ES)
DATA DE PUBLICAÇÃO

2006

RESUMO

When indicating the number of spermatozoa produced in an adult animal, the neonatal period, in which the final number of Sertoli cells is established in rats, is key. It is believed that the main mitogenic factor of Sertoli cells is the FSH, while the thyroid hormone triiodothyronine (T3) would be responsible for the regulation of the maturation/differentiation of such cells. However, the treatment with the goitrogenic drug PTU has demonstrated that, despite the plasmatic levels of FSH remain very low during the treatment period, the transitory hypothyroidism in the neonatal period takes to a sharp increase of the Sertoli cells population per testis and sperm production in rodents such as rats, mice, and hamsters. Investigating the degree of proliferation of the Sertoli cells in hypothyroid animals, is the main objective of the present work, in which the FSH secretion was suppressed by the treatment with a powerful GnRH agonist/antagonist (Leuprolide) or GnRH antagonist (Antide). Also, the effect of the neonatal treatment with a single dose of leuprolide in the testicular development and the plasmatic levels of FSH of Wistar rats was investigated. The results found during the postnatal development of the testis suggest that the treatment with leuprolide of long duration promoted initial increase in the proliferation of the Sertoli cells, probably due to initial rise of the FSH levels. However, from the first day of treatment, this drug suppressed the levels of FSH for almost 5 weeks, what probably was responsible for the substantial reduction of the testis weight and the number of Sertoli cells per testis in the adult rats. Although both leuprolide and antide work as GnRH antagonist, some morphofunctional results found in adult-rat testis had shown that these drugs don t necessarily promote the same effects, specially in relation to the function of the Leydig and Sertoli cells that seem to be more compromised in the animals treated with antide. Surprisingly, the treatment with PTU+leuprolide did not provide the expected results for testis weight, for Sertoli cell number per testis and daily sperm production, what remained within the same range as of those animals treated with PTU. In fact, the results found in rats treated with PTU+leuprolide and sacrificed between 30 and 43 days of age had shown that in this condition the Sertoli cells remained immature and with prolonged proliferative capacity, being therefore capable to proliferate during a longer time period in which the FSH levels were probably high after ceasing the suppressor effect of leuprolide in the gonadotropin-releasing hormone (GnRH)

ASSUNTO(S)

rato como animal de laboratório teses testículo teses sertoli, células de teses reprodução animal teses hipotireoidismo teses

ACESSO AO ARTIGO

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