Electrophysiological Study on the Effect of the Amygdaloid Nucleus Stimulation on Uterine Movement in Rabbits

Abstract

Using rabbits, changes in uterine movement induced by electric stimulation of the amygdaloid nucleus which belongs to the limbic system were investigated in relation to electrical activities of the central nervous system expressed by these stimuli.
1) When 3Hz stimuli were applied to the amygdaloid nucleus, spike and wave complexes appeared on the cerebral cortex EEG. When the stimulus frequency was increased to 8Hz, the EEG showed a recruiting response. With 100Hz, an arousal pattern appeared on the EEG.
2) Stimulation of the corticomedial division of the amygdaloid nucleus induced an acceleration of uterine movement, suggesting a close association between the corticomedial division and uterine movement-accelerating system.
3) Stimulation of the basolatera l division induced an inhibition of uterine movement, suggesting a close association between the basolateral division and uterine movement-inhibiting system.
4) Administration of anticholinergic drugs led to complete disappearance of the accelerating effect of the corticomedial division, while the inhibiting effect of the basolateral division persisted. In contrast, with the administration of β-adrenergic blocking agents the entire accelerating effect of the corticomedial division persisted, while the inhibiting effect of the basolateral division disappeared. With the administration of α- adrenergic blocking agents the inhibiting effect of the basolateral division persisted. These findings suggest that the changes in uterine movement induced by stimulation of the corticomedial division are mediated by cholinergic receptors while the changes in uterine movement induced by stimulation of the basolateral division are mediated by β-adrenergic receptors.
5) When changes in uterine movement induced by stimulation of the amygdaloid nucleus were similarly followed in rabbits subjected to adrenalectomy or destruction of the infundibulum, the results were similar to those obtained prior to these procedures. These findings suggest that the influence exerted by stimulation of the amygdaloid nucleus on uterine movement is not mediated by humoral factors.
6) No changes in amygd aloid nucleus stimulation-induced uterine movement were found in rabbits subjected to transection of the spinal cord at the C6-C7 level.
7) In rabbits subjected to transection of the spinal cord at the L5-L6 level the accelerating effect on uterine movement induced by stimulation of the corticomedial division disappeared. This finding suggests that the effect of stimulation of the corticomedial division is mediated by the sacral parasympathetic nerves.