Effect of synaptic blockade on thermosensitive neurons in hypothalamic tissue slices.
To understand the basis of hypothalamic neuronal thermosensitivity, single-unit activity was recorded in vitro, from constantly perfused tissue slices of rat preoptic area and anterior hypothalamus, PO/AH. The firing rate and thermosensitivity of individual PO/AH neurons was determined before, during, and after tissue perfusion with a synaptic blocking medium, containing elevated magnesium and decreased calcium concentrations. During synaptic blockade, thermosensitivity was retained in nearly all of the warm-sensitive neurons, and some temperature-insensitive neurons showed increased warm sensitivity. The thermosensitivity of all cold-sensitive neurons was lost during synaptic blockade. These results support the hypothesis that PO/AH cold-sensitive neurons depend on synapses from nearby warm-sensitive neurons for their temperature sensitivity; whereas warm sensitivity is an independent property of certain PO/AH neurons.
D000818:Animals; D002118:Calcium / Q000494:pharmacology; D004553:Electric Conductivity; D007032:Hypothalamus, Anterior / Q000187:drug effects / Q000502:physiology*; D066298:In Vitro Techniques; D008274:Magnesium / Q000494:pharmacology; D008297:Male; D009474:Neurons / Q000187:drug effects / Q000502:physiology*; D011301:Preoptic Area / Q000502:physiology*; D051381:Rats; D011919:Rats, Inbred Strains; D013569:Synapses / Q000187:drug effects / Q000502:physiology*; D013696:Temperature
D008274:Magnesium; D002118:Calcium