Reprod. Nutr. Dev. 46 (2006) 157-166
DOI: 10.1051/rnd:2006001

Neonatal treatment with naloxone increases the population of Sertoli cells and sperm production in adult rats

Valdemiro Amaro da Silva Jr.^a, Aerlem Cynara S. Vieira^a, Catarina Ferreira Pinto^a, Tarcízio Antônio R. de Paula^b, Mariza B. Palma^a, Marleyne José A. A. Lins Amorim^a, Adelmar A. Amorim Jr^c and Raul Manhães-de-Castro<sup>c

a</sup>  Departamento de Morfologia e Fisiologia Animal, Universidade Federal Rural de Pernambuco, Recife, PE, Brasil, 52171-900
^b  Departamento de Medicina Veterinária, Universidade Federal de Viçosa, Viçosa - MG - Brasil
^c  Universidade Federal de Pernambuco, Recife, PE, Brasil, 50670-901

(Received 27 April 2005; accepted 20 November 2005; published online 6 April 2006)

Abstract - Endogenous opioid peptides play an important role in the ontogenesis of the functional and morphological parameters of the seminiferous epithelium. The aim of this study was to evaluate the effects of neonatal manipulations with naloxone, an opioid antagonist, on the population of Sertoli cells and on sperm production in adult rats. Rats were assigned to receive 8 g per gram of body weight twice a day with interval of 8 h of naloxone and they were compared to a control group receiving saline. Naloxone groups presented the following findings when compared to the control group: increased body weight from the 2nd to the 27th day; a smaller seminiferous epithelium height, smaller seminiferous tubule diameter, increased number of Sertoli cells and daily sperm production per testis, increased daily sperm production per gram per testis and increased total length of the seminiferous tubule of the treated groups. According to our study, the neonatal treatment with naloxone during the critical period of testis development was able to change the proliferative dynamics of Sertoli cells by an intra and/or extra testicular blockage of opioid receptors, confirming the direct relation between the number of Sertoli cells and the number of spermatozoids.

Key words: naloxone / testis development / Sertoli cells / sperm production / rats

Corresponding author: Valdemiro Amaro da Silva Jr. valdemiro.amaro@bol.com.br

© INRA, EDP Sciences 2006