Effect of Selective Lesioning of Brain Serotonin or Catecholamine-Containing Neurons on the Activity of Oral Steroid Contraceptives in Rats

Abstract

The effect of different dosage combinations of lynoestrenol and mestranol were studied in rats that have been subjected to selective lesioning of brain serotonin or catecholamine-containing neurons. Lesions of the midbrain raphe, which cause a marked decrease of serotonin in the forebrain, were without any effect on the estrus cycle, fertility and activity of the steroids under study. An intraventricular injection of 6-hydroxydopamine, which causes a selective decrease of noradrenaline and dopamine in the forebrain, produced a transient effect only on the estrus cycle but did not significantly change the fertility or the activity of the substances investigated. The data indicate that the integrity of monoaminergic neurons in the brain is not an essential condition for the aspects investigated in the present study.

The influence of raphe nucleus lesions on fertility in the female rat

“…It was found that on the 15th day of pregnancy in females mated on the 10th day after lesioning of a DR or MR nucleus, there is no significant dif¬ ference, as compared with the control groups, in number of live or resorbed foetuses, foetal weights, or weights of ovaries. Bernasconi et al (1975) obtained similar results in the early foetal period.…”

“…Mating of the female rats occurred on the 10th day after raphe nuclei lesion; at this time there was a significant decrease in forebrain 5-HT level (Kostowski et al 1968;Bernasconi et al 1975;Waloch et al 1978), increased reléase of Iuteinizing hor¬ mone (LH) and a rise in number of Graafian follicles and corpora lutea (Waloch et al 1978 and to be publ. ; Waloch & Paszko, to be publ.…”