Electrophysiological and pharmacological studies of amygdalo-hypothalamic connections in the rat.

Electrophysiological techniques have been used to investigate the neural connections between the amygdala and the rostral hypothalamus of female rats. Recordings have been made from 120 neurones in the preoptic/anterior hypothalamic area (POA/AHA) which could be driven by electrical stimulation of the amygdala. 89% of the neurones were activated orthodromically and, of these, 2 groups have been distinguished according to the latency of the responses. The remainder of identified cells were antidromically activated by stimulation of the amygdala. The response of these identified preoptic cells to the iontophoretic application of dopamine (DA) and noradrenaline (NA) has also been investigated. DA inhibited the spontaneous or glutamate-induced activity in 18 of 21 identified cells so tested and NA inhibited all 25 units; excitation was never observed. The role of the amygdala and of aminergic pathways in the control of ovulation is discussed.