Prostaglandin E(2) has antinociceptive effect through EP(1) receptor in the ventromedial hypothalamus in rats.
The effects of microinjection of prostaglandin E(2) (PGE(2)) (50 fg-50 ng/0.2 microl) into the ventromedial hypothalamus (VMH) on nociception were studied using a hot-plate test in rats. Microinjection of PGE(2) (5-500 pg and 50 ng/0.2 microl) into the VMH significantly prolonged the paw-withdrawal latency on a hot plate 5 and 10 min after injection, respectively. Maximal prolongation was obtained 5 min after the injection of PGE(2) at 5 pg. Subsequently, to determine whether the PGE(2) receptor subtype EP(1) is involved in the PGE(2)-induced antinociceptive effect in the VMH, we observed the changes in nociception after intraVMH microinjection of SC19220, an EP(1) receptor antagonist, and 17-phenyl-omega-trinor PGE(2), an EP(1) receptor agonist. Simultaneous injection of SC19220 (150 ng) with PGE(2) (500 pg) into the VMH blocked the PGE(2)-induced prolongation of the paw-withdrawal latency. Moreover, an intraVMH microinjection of 17-phenyl-omega-trinor PGE(2) (500 pg) prolonged it. These results indicate that PGE(2) in the VMH has antinociceptive effect through its actions on EP(1) receptors in rats.
Hosoi
M
M
Department of Psychosomatic Medicine, Kyushu University Faculty of Medicine, Fukuoka, Japan.
Oka
T
T
Abe
M
M
Hori
T
T
Yamamoto
H
H
Mine
K
K
Kubo
C
C
D000700:Analgesics / Q000008:administration & dosage / Q000494:pharmacology*; D000704:Analysis of Variance; D000818:Animals; D001931:Brain Mapping; D015232:Dinoprostone / Q000008:administration & dosage / Q000494:pharmacology*; D006614:Hindlimb; D008297:Male; D008845:Microinjections; D010146:Pain / Q000188:drug therapy / Q000503:physiopathology*; D051381:Rats; D017208:Rats, Wistar; D011930:Reaction Time; D018078:Receptors, Prostaglandin E / Q000187:drug effects / Q000502:physiology*; D058306:Receptors, Prostaglandin E, EP1 Subtype; D014697:Ventromedial Hypothalamic Nucleus / Q000187:drug effects / Q000502:physiology* / Q000503:physiopathology
D000700:Analgesics; D018078:Receptors, Prostaglandin E; D058306:Receptors, Prostaglandin E, EP1 Subtype; D015232:Dinoprostone