Effects of Short-term Hyper- and Hypoprolactinaemia on Hormones of the Pituitary, Gonad and -Thyroid Axis and on Semen Quality in Male Beagles

Contents Effects of a short‐term hyper‐ and hypoprolactinaemia on serum concentrations of LH, testosterone and semen quality in six male Beagles were investigated. Blood samples were collected at 3‐day intervals for 12 weeks. The time span was divided into five 3‐week periods: pre‐treatment, metoclopramide (MCP) treatment (0.2 mg/kg orally three times daily), cabergoline (CAB) treatment (5 μg/kg orally once daily), post‐treatment 1 and post‐treatment 2. In the latter, only semen characteristics were evaluated. Semen parameters were analyzed once per week during the whole 15‐week investigation time. At the end of each period, the effects of a single intravenous injection of thyrotropin‐releasing hormone (TRH; 10 μg/kg) on the secretion of prolactin (PRL), LH, testosterone, thyroid‐stimulating hormone and thyroxine (T4) were investigated. Pre‐treatment serum PRL concentration increased under MCP (p