Central oxytocin potentiates excitatory responses of oxytocin neurones to stimulation of the dorsomedial hypothalamic nucleus in the suckled rat.
Experiments were undertaken to investigate the effects of intracerebroventricular (i.c.v.) oxytocin (OT) on the response of supraoptic OT neurones to stimulation of the dorsomedial nucleus (DMH), in the suckled lactating rat. Under control conditions, the majority of OT neurones displayed either weak excitation to DMH stimulation, or no response. Following i.c.v. OT injection, all neurones showed a pronounced long-latency (70-115 ms) excitatory response, and the number of spikes evoked per stimulus pulse was significantly increased. This increased excitatory response was accompanied by facilitation of the milk-ejection reflex. Some OT neurones also displayed a short latency (8-13 ms) excitation to DMH stimulation, but this was unaffected by i.c.v. OT. In conclusion, the facilitation of bursting in OT neurones by i.c.v. OT is associated with potentiation of long-latency excitatory responses evoked by DMH stimulation.
Cosgrave
A S
AS
Department of Anatomy, School of Medical Sciences, University of Bristol, University Walk, Bristol BS8 1TD, UK.
Wakerley
Jon B
JB
D000200:Action Potentials / Q000187:drug effects / Q000502:physiology*; D000818:Animals; D004302:Dorsomedial Hypothalamic Nucleus / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D004558:Electric Stimulation; D005260:Female; D007276:Injections, Intraventricular; D007774:Lactation / Q000502:physiology*; D009433:Neural Inhibition / Q000187:drug effects / Q000502:physiology; D009434:Neural Pathways / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D009474:Neurons / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D010121:Oxytocin / Q000378:metabolism* / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D011930:Reaction Time / Q000187:drug effects / Q000502:physiology; D013495:Supraoptic Nucleus / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D009435:Synaptic Transmission / Q000187:drug effects / Q000502:physiology
D010121:Oxytocin