Histamine acts directly on calcitonin gene-related peptide- and substance P-containing trigeminal ganglion neurons as assessed by calcium influx and immunocytochemistry.
Primary cultures of rat trigeminal ganglion cells were exposed to histamine, and the intracellular free-calcium concentrations, [Ca2+]i, were measured by the calcium-sensitive dye fura-2. Histamine (10(-6)-10(-2) M) increased the [Ca2+]i of the neurons. Pretreatment of the cells with histamine H1-receptor blocker pyrilamine (10(-4) M), or chelation of extracellular calcium, abolished the response; however, the response was not altered by pretreatment with H2-blocker cimetidine (10(-2) M). Thus, the increase in [Ca2+]i was due to the influx of extracellular calcium mediated by H1-receptor. Immunocytochemical analysis showed that these cultured cells that respond to histamine were identically calcitonin gene-related peptide (CGRP)- or substance P (SP)-like immunoreactive. The findings suggested that histamine released from mast cells directly affected CGRP- and SP-containing sensory neurons via H1-receptor, which convey nociceptive information.
Tani
E
E
Department of Otolaryngology, Kumamoto University School of Medicine, Japan.
Ishikawa
T
T
D000818:Animals; D015740:Calcitonin Gene-Related Peptide / Q000032:analysis; D002118:Calcium / Q000032:analysis / Q000378:metabolism*; D006632:Histamine / Q000502:physiology*; D066298:In Vitro Techniques; D051381:Rats; D011969:Receptors, Histamine H1 / Q000502:physiology; D013373:Substance P / Q000032:analysis; D012668:Trigeminal Ganglion / Q000502:physiology*
D011969:Receptors, Histamine H1; D013373:Substance P; D006632:Histamine; D015740:Calcitonin Gene-Related Peptide; D002118:Calcium