Effect of acetylcholine, prostaglandin F2 alpha and estradiol on number of sperm in the reproductive tract of inseminated rabbits.

Acetylcholine, injected im into does immediately after natural mating, significantly increased the number of sperm recovered 1 h later from the vagina and cervices but not from the oviducts. Acetylcholine caused immediate increases in the frequency and amplitude of uterine contractions as measured by strain-gauge force transducers attached to the serosa and recorded by physiograph; contraction patterns returned to the preinjection pattern within 30 min. Administration of prostaglandin F2 alpha (.75 mg) at the time of insemination increased sperm numbers significantly at 2.5 h in the oviducts, uterus and cervices; .15 or 3.75 mg caused relatively little increase in sperm numbers. Prostaglandin F2 alpha increased the number and strength of uterine contractions for more than 30 min. Estradiol injected 1 h before artificial insemination increased the number of sperm recovered from the oviducts, uterus, cervices and vagina at 2.5 h after insemination. Estradiol caused little if any detectable increase in the frequency or strength of uterine contractions during the period of increased retention and transport of sperm. When does were inseminated with low numbers of sperm (86,000), prostaglandin F2 alpha and phenylephrine, used for comparison, each increased the ovum fertilization rate (22% for control does; 76 and 73%, respectively, for prostaglandin F2 alpha- or phenylephrine-treated does).