Impact of Nonselective Muscarinic Cholinergic Antagonist (Atropine) on Goat Semen Quality and Seminal Fluid Volume

Abstract

The parasympathetic nervous system plays an important role in controlling the semen quality via manipulation of accessory glands in many species. Seminal fluid has a negative impact on semen cryopreservation in goats. We hypothesized that reducing the secretion of seminal fluid during semen collection may help to improve the quality of semen cryopreservation. In this study, we used atropine to inhibit the parasympathetic pathway. Six different concentrations (0.02, 0.04, 0.08, 0.1, 0.15 and 0.2 mg/kg) of atropine were tested in twelve male goats. The final concentration (0.2 mg/kg) was tested in two consecutive semen collections. Physiological changes, including heart rate and pupil response, were evaluated before and after the atropine injection. The results revealed that atropine did not affect most of the reproductive system, including copulation, ejaculation, semen quality and seminal fluid volume, protein concentration and protein profile. However, some dosages of atropine affected other body systems, such as increased heart rate at a dose of more than 0.1 mg/kg and pupil dilation at a dose greater than 0.04 mg/kg. In conclusion, we proposed that parasympathetic inhibition by atropine did not impact the goat's male reproductive system and suggested that the parasympathetic system may not be important for regulating the male reproductive system in goats.