Neuronal histamine release elicited by hyperthermia mediates tracheal dilation and pressor response.
Whether brain histaminergic neurons contribute to the regulation of tracheal tone and peripheral vascular tone under hyperthermia was investigated in anesthetized rabbits. Histamine release from the rostral ventrolateral medulla (RVLM), the raphe nuclei, and the solitary nucleus of the medulla oblongata was significantly increased by hyperthermia. The increased histamine was significantly suppressed by 10(-6) M tetrodotoxin microdialyzed in each area. Tracheal pressure and mean arterial pressure were significantly decreased and increased by hyperthermia, respectively. An H(1)-receptor antagonist, 5 x 10(-6) M (+)-chlorpheniramine, bilaterally microdialyzed in the RVLM significantly enhanced histamine release in the RVLM as well as significantly suppressed tracheal dilation and pressor response caused by hyperthermia. These data indicate that histamine release in the medulla oblongata is enhanced by hyperthermia. The enhanced histamine is the neuronal origin and the cause of tracheal dilation and pressor response at least via H(1) receptors in the RVLM. Brain histaminergic neurons play important roles in tracheal tone and peripheral vascular tone via H(1) receptors in the RVLM and homeostasis on body temperature.
Kanamaru
M
M
Department of Physiology, Showa University School of Medicine, Shinagawa-ku, Tokyo 142-8555, Japan.
Iwase
M
M
Homma
I
I
D000818:Animals; D001794:Blood Pressure; D001831:Body Temperature; D002744:Chlorpheniramine / Q000494:pharmacology; D005334:Fever / Q000378:metabolism* / Q000503:physiopathology; D006632:Histamine / Q000378:metabolism; D006633:Histamine Antagonists / Q000494:pharmacology; D006634:Histamine H1 Antagonists / Q000494:pharmacology; D006636:Histamine Release / Q000187:drug effects / Q000502:physiology*; D007031:Hypothalamus / Q000473:pathology / Q000503:physiopathology; D008526:Medulla Oblongata / Q000378:metabolism; D009126:Muscle Relaxation; D009130:Muscle, Smooth / Q000503:physiopathology; D009474:Neurons / Q000378:metabolism* / Q000502:physiology; D011312:Pressure; D011817:Rabbits; D011903:Raphe Nuclei / Q000378:metabolism; D017552:Solitary Nucleus / Q000378:metabolism; D009435:Synaptic Transmission / Q000502:physiology; D013779:Tetrodotoxin / Q000494:pharmacology; D014132:Trachea / Q000503:physiopathology*
D006633:Histamine Antagonists; D006634:Histamine H1 Antagonists; D002744:Chlorpheniramine; D013779:Tetrodotoxin; D006632:Histamine