Intracellular recordings from neurons of the arcuate nucleus in superfused explants of rat hypothalamus.
The membrane properties of arcuate nucleus (ARN) neurons and their connections with extranuclear regions were examined in vitro, using intracellular recordings obtained in superfused explants of rat hypothalamus. Current-clamp analysis revealed that the electroresponsive properties of a large proportion of ARN neurons are influenced by the expression of various forms of low threshold rectification. When the initial membrane potential of a neuron was maintained negative to -70 mV, depolarizing current injection could precipitate an immediate bursting response, due to the activation of a low-threshold spike, or delay firing as a result of transient outward rectification. These properties represent a means by which changes in membrane potential may modulate the responsiveness of ARN neurons to synaptic input. Indeed, electrical stimulation revealed that in addition to efferent projections to the supraoptic nucleus, medial preoptic area, or neurointermediate pituitary, subgroups of ARN neurons may receive a reciprocal, or collateral innervation from each of these areas. This functional diversity of intrinsic and synaptic mechanisms provides ARN neurons with a high capacity for the complex local processing of afferent information.
MacMillan
S J
SJ
Centre for Research in Neuroscience, Montreal General Hospital and McGill University, Canada.
Bourque
C W
CW
D000818:Animals; D001111:Arcuate Nucleus of Hypothalamus / Q000166:cytology / Q000502:physiology*; D004558:Electric Stimulation; D005071:Evoked Potentials / Q000502:physiology; D066298:In Vitro Techniques; D008297:Male; D008564:Membrane Potentials / Q000502:physiology; D009474:Neurons / Q000502:physiology*; D010477:Perfusion; D051381:Rats; D013569:Synapses / Q000502:physiology