Constant light exposure cause dissociation in gonadotrophins secretion and inhibits partially neuroendocrine differentiation of Leydig cells in adult rats.

ORTEGA HH; LORENTE JA; MIRA GA,; BARAVALLE C; SALVETTI NR

REPRODUCTION IN DOMESTIC ANIMALS (1990)

Blackwell

Lugar: Berlin; Año: 2004 vol. 39 p. 417 - 423

0936-6768

The objective of this work was to study the changes that occur in the Leydig cells of rats exposed to continuous light. The laboratory rat is considered a non photoperiodic specie because exposure to short photoperiod has little or no effect on reproductive status. However, exposure of adult female rats to constant light induces polycystic ovaries, indicating that extreme changes in the photoperiod are able to affect seriously the reproductive function. Adult male rats were placed under continuous light conditions during 15 weeks. After this period, the animals were sacrificed and testicles were dissected and processed by routine histologic protocols. FSH and LH serum levels were determined by RIA. The visualization of antigens was achieved by the streptavidin-peroxidase immunohistochemical method. Antibodies against Chromogranin A, S-100 Protein, P Substance, Synaptofisin, Neurofilament Protein-200, Gliofibrillary Acidic Protein and Neuron Specific Enolase were used. The mean LH serum concentration was significantly lower, while the mean FSH level was significantly higher in treated animals. The expression of S-100, NSE, CrA, SP and SYN was significantly lower in treated animals. In conclusion, the constant light exposure acting directly at the pituitary level decreases LH secretion. The increased FSH secretion may be due to a partial reduction of the negative androgen feedback in the pituitary gland. Also, the constant light exposure affects the expression of some immunomarkers in Leydig cells, possibly due to the changes found in the gonadotrophins levels and feedback mechanism.