Serum luteinizing hormone response to administration of gonadotropin-releasing hormone to atrazine-treated gilts.

Abstract

The aim of the study was to evaluate the response of porcine luteinizing hormone (pLH) in serum to a single iv administration of gonadotropin-releasing hormone (GnRH) in atrazine-treated pigs. Experiments were performed in 15 mature female pigs (10 atrazine-treated, 5 control). From the onset of estrous (day 0), the pigs were given 1 mg atrazine/kg body mass in feed for 20 d of the estrous cycle. On the last day, blood samples were collected at min 0 from control and atrazine-exposed, and 5 atrazine-exposed pigs were immediatey given 100 mg GnRH iv. Blood samples were collected from atrazine-exposed and the GnRH-injected atrazine-exposed groups at 20, 30, 40 and 90 min and serum pLH concentrations were determined by radioimmunoassay. The administration of atrazine led to significant (p< 0.001) suppression of serum pLH concentrations (0.57 +/- 0.05 ng/ml) compared to control animals (2.24 +/- 0.20 ng/ml). The single iv GnRH administration to the atrazine-exposed pigs provoked significant pLH release at 20 and 30 min after GnRH administration, indicating attenuation of GnRH release in the atrazine-exposed animals was responsible for the suppression of serum pLH.