Difference in receptor-binding contributes to difference in biological activity between the unique guinea pig GnRH and mammalian GnRH.

In the current study, we compared the in vitro potency of a unique form of gonadotropin-releasing hormone (GnRH) present in the brain of the guinea pig (gpGnRH) with that of mammalian GnRH (mGnRH) as well as their binding affinities to the GnRH receptor. In gpGnRH, the highly conserved histidine in position 2 (His(2)) and leucine in position 7 (Leu(7)) are substituted by tyrosine and valine, respectively. In vivo, gpGnRH was shown to be less potent than mGnRH, possibly in part because of higher susceptibility to enzymatic degradation.

Further evaluation of the biological activity of the unique gonadotropin-releasing hormone peptide in the guinea pig brain.

In this study we compared the biological activity of a unique form of gonadotropin-releasing hormone (GnRH) in the brain of the guinea pig (gpGnRH) with mammalian GnRH (mGnRH). In gpGnRH, the highly conserved histidine in position 2 (His(2)) and leucine in position 7 (Leu(7)) are substituted by tyrosine and valine, respectively. The gpGnRH was less potent than mGnRH in stimulating the release of luteinizing hormone (LH) in vivo in the guinea pig and displayed only low activity in the rat.

Internal exposure to pollutants and sexual maturation in Flemish adolescents.

Flanders is densely populated with much industry and intensive farming. Sexual maturation of adolescents (aged 14-15 years) was studied in relation to internal exposure to pollutants. Serum levels of pollutants and sex hormones were measured in 1679 participants selected as a random sample of the adolescents residing in the study areas.

Internal exposure to pollutants and body size in Flemish adolescents and adults: associations and dose-response relationships.

Flanders is densely populated with much industry and intensive farming. Body size of 14- to 15-year old adolescents and of adults aged 50-65 was studied in relation to internal exposure to pollutants. 1679 adolescents (887 boys and 792 girls), 775 men and 808 women were selected as a random sample of the population.

Internal exposure to pollutants and sex hormone levels in Flemish male adolescents in a cross-sectional study: associations and dose-response relationships.

Flanders is densely populated with much industry and intensive farming. Hormonal status of 14- to 15-year-old male adolescents was studied in relation to internal exposure to pollutants. A total of 887 participants were selected as a random sample of the adolescents residing in the study areas.