Modulation of glutamate-induced outward current by prostaglandin E(2) in rat dissociated preoptic neurons.
The preoptic/anterior hypothalamus (POA) is one of the major brain regions where cytokines and their related mediators (i.e., prostaglandins) exert diverse actions. In the present study, the modulatory effects of prostaglandin E(2) (PGE(2)) on the glutamate-induced membrane currents were examined using perforated-patch clamp method in rat POA neurons that had been mechanically dissociated by vibration without enzyme treatment. Application of glutamate through U-tube induced a slow outward current following fast inward ionotroic current at a holding membrane potential of -30 mV. The slow outward current was also induced by N-methyl-d-aspartate (NMDA), accompanied by an increased membrane conductance, and inhibited by perfusion with Ca(2+)-free solution, tetraethylammonium chloride (TEA), and apamin, suggesting a Ca(2+)-dependent K(+) current (KCa) activated by Ca(2+) entry through NMDA channels. Perfusion with PGE(2) at 0.1-10 microM, a principal mediator of fever and neuroendocrine control at the POA, did not produce apparent current by itself, but selectively potentiated the glutamate- or NMDA-induced KCa without affecting inward currents. The KCa induced by activation of NMDA receptors may serve as a feedback mechanism and the modulatory effects of PGE(2) on the KCa may have an important physiological significance.
Katafuchi
Toshihiko
T
Department of Integrative Physiology, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582 Japan. kataf@physiol.med.kyushu-u.ac.jp
Duan
Shumin
S
Take
Sachiko
S
Yoshimura
Megumu
M
D000818:Animals; D002469:Cell Separation; D015232:Dinoprostone / Q000494:pharmacology*; D018690:Excitatory Amino Acid Agonists / Q000494:pharmacology; D008297:Male; D009474:Neurons / Q000187:drug effects / Q000378:metabolism*; D018408:Patch-Clamp Techniques; D010477:Perfusion; D026902:Potassium Channel Blockers / Q000494:pharmacology; D024681:Potassium Channels, Calcium-Activated / Q000187:drug effects / Q000378:metabolism; D011301:Preoptic Area / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D017470:Receptors, Glutamate / Q000187:drug effects*; D016194:Receptors, N-Methyl-D-Aspartate / Q000819:agonists; D019789:Tetraethylammonium / Q000494:pharmacology; D014732:Vibration
D018690:Excitatory Amino Acid Agonists; D026902:Potassium Channel Blockers; D024681:Potassium Channels, Calcium-Activated; D017470:Receptors, Glutamate; D016194:Receptors, N-Methyl-D-Aspartate; D019789:Tetraethylammonium; D015232:Dinoprostone