Potentials evoked in the Hypothalamus and Cerebral Cortex by Electrical Stimulation of the Uterus

Abstract

AFTER the 36th week of pregnancy, labour is readily initiated by such procedures as dilating the cervix, passing uterine bougies and, most effectively, by amniotomy. This ability to initiate labour by mechanical interference suggests the existence of nervous pathways from uterus to hypothalamus. The presence of appropriate receptors in the rabbit uterus has been demonstrated by Ferguson¹ and by Bower², but little is known of the central pathways involved. In the experiments recorded here on cats anæsthetized with chloralose we used the evoked potential technique to detect uterine afferent relays to the hypothalamus. Pairs of stainless steel stimulating electrodes were implanted into the myometrium, one pair high in one uterine horn and another pair below the level of fusion of the two horns, but above the vagina. The uterus was then subjected to direct electrical stimulation through either pair of electrodes by square wave pulses of 1–3 msec duration.