Existence of capsaicin-sensitive glutamatergic terminals in rat hypothalamus.
Capsaicin has been suggested to act not only on thin primary afferents but also on the hypothalamus, but the neurotransmitter(s) of central capsaicin-sensitive neurons are unknown. The present study was conducted to determine whether any central, especially hypothalamic, glutamatergic terminals were sensitive to capsaicin. Capsaicin evoked glutamate release from slices of hypothalamus and lumbar dorsal horn, but not cerebellum. Such capsaicin action was Ca2+ dependent and inhibited by the capsaicin antagonist capsazepine. Vanilloid receptor subtype 1 mRNA was widely distributed in the brain, with a marked level in the hypothalamus and cerebellum, but not in the spinal cord. The results suggest that there are glutamatergic terminals sensitive to capsaicin in the hypothalamus.
Department of Applied Pharmacology, Faculty of Pharmaceutical Sciences, Toyama Medical and Pharmaceutical University, Sugitani, Japan.
T
T
Sasamura
M
M
Sasaki
C
C
Tohda
Y
Y
Kuraishi
D000818:Animals; D001923:Brain Chemistry / Q000187:drug effects; D002211:Capsaicin / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D018698:Glutamic Acid / Q000502:physiology*; D007031:Hypothalamus / Q000166:cytology* / Q000187:drug effects; D008297:Male; D009411:Nerve Endings / Q000187:drug effects*; D016133:Polymerase Chain Reaction; D011189:Potassium Chloride / Q000494:pharmacology; D012333:RNA, Messenger / Q000096:biosynthesis; D051381:Rats; D017207:Rats, Sprague-Dawley; D011955:Receptors, Drug / Q000096:biosynthesis / Q000187:drug effects
D012333:RNA, Messenger; D011955:Receptors, Drug; D018698:Glutamic Acid; D011189:Potassium Chloride; D002211:Capsaicin