Influence of castration upon trophism and reactivity of rat seminal vesicles

1. Castration-induced time-dependent changes in trophism and reactivity of rat seminal vesicles were studied by measuring vesicle weight, spontaneous contractility, apparent sensitivity (pD2) to acetylcholine and acetyl-beta-methylcholine and intrinsic reactivity (alpha) to acetyl-beta-methylcholine 5, 10, 15 and 30 days after surgery. 2. The wet and dry weights of the seminal vesicles from castrated rats were less than those from the controls 5 days after castration, and decreased with time after gonadectomy. Spontaneous contractility was observed 15 days after surgery. The pD2 for acetyl-beta-methylcholine was significantly higher than normal control values (5.81 +/- 0.09 vs. 5.34 +/- 0.12) 10 days after orchidectomy, whereas the change in sensitivity to acetylcholine (from 5.04 +/- 0.15 to 5.95 +/- 0.95) was detected only 30 days after castration. In contrast, a change in alpha from 0.75 +/- 0.04 (normal control) to 0.90 +/- 0.02 was detected on the 5th day after castration. 3. These data show that atrophy and spontaneous contractility of rat seminal vesicles, as well as increased sensitivity and reactivity to parasympathetic drugs are detectable at different times after castration.