Effects of reserpine on the sensitivity of rat isolated uteri preparations to oxytocic drugs

Abstract

Abstract Stimulant activity of the isolated uteri of female virgin rats to acetylcholine, 5-hydroxytryptamine, and oxytocin was examined quantitatively (4-point assay method) in anoestrus, induced oestrus (diethylstilboestrol 10μg/100 g body weight injected subcutaneously), reserpinized and stilboestrol-treated reserpinized animals. Each group had 30 animals. Reserpine was administered intraperitoneally in two doses each of 1 mg/kg body weight on the first and third days of dioestrus. The sensitivity to acetylcholine, 5-hydroxytryptamine and oxytocin of the uteri in induced oestrus was increased by 20, 86 and 730 times respectively. In the group of animals receiving reserpine alone the experiment could not be made due to persistant spontaneous activity (even up to 2 hr) of the uterine tissue. In the stilboestrol-treated reserpinized group, the sensitivity to all the oxytocic drugs was as low as in anoestrous tissue. Thus, stilboestrol injection failed to increase the sensitivity of the rat uteri to oxytocic drugs or to produce changes in the vaginal smear pattern. The possibility of progesterone being present in the tissue due to persistance of corpora lutea after reserpine is put forward.