Effects of HCG or gonadoreline on seminal parameters and plasma testosterone levels in young male rabbits

The effect of successive HCG or Gonadoreline injections on some reproductiv e parameters in 21 young male rabbits, aged from 4 to 4.5 months, has been studied. Animals were randomly allocated in three groups of seven to receiv e weekly ton each Monday) i.m. injections of 20 mg Gonadoreline, 50 IU HCG, or 0.5 mi Saline solution, respectively. The ejaculate from each male was collected and analysed twice a week (Tuesday and Friday). Higher sperm volu mes were observed on the first week after Gonadoreline administration compa red to the other groups (p < 0.05), and lower values during the second week in the Control group vs. Gonadoreline group (p < 0.05). Sperm volume incre ases after the 3(rd) week in Control animals (p < 0.05). When considering t he global period studied, mean sperm volumes achieved after Gonadoreline tr eatment were higher than in HCG or Control group. Despite the random distri bution of the animals to each treatment, and although throughout the experi ment more ejaculates were discarded in the Gonadoreline group, the final nu mber of doses obtained per ejaculate was higher in this group followed by H CG treated animals. Globally, the mean sperm concentration of the Control g roup during the entire studied period was significatively lower compared to the other groups (p < 0.001). No sperm motility differences were detected among the groups (p < 0.1174). HCG injections caused a significative increa se in plasma testosterone concentration during the first and second week (p < 0.001) and similar plasma levels were observed in all groups afterwards. No direct plasma testosterone increasing levels owed to Gonadoreline injec tions were detected, probably due to the frequency of blood sampling (once a week).