Inhibition of calcitonin gene-related peptide by h-CGRP(8-37) antagonizes the cerebral dilator response from nasociliary nerve stimulation in the cat.
The head is innervated by neurons with cell bodies in the trigeminal ganglion that contain both calcitonin gene-related peptide (CGRP) and substance P. The CGRP-containing neurons preferentially innervate the cerebral vessels and when activated produce both an increase in blood flow and local release of CGRP. In this study, the CGRP antagonist h-CGRP(8-37) was examined for its ability to interfere with trigeminal-evoked cerebral vasodilator responses in the alpha-chloralose anaesthetised cat. Nasociliary nerve stimulation produced a characteristic frequency-dependent increase in cerebral cortical blood flow with a mean maximum of 35 +/- 7% at 20 Hz. Following administration of h-CGRP(8-37), this response was reduced by half with a general shift to the right of the frequency-response curve. These data further support the view that CGRP is an important transmitter agent in the trigeminovascular system that is responsible for a great part of the vasodilator capacity of trigeminal neurons.
Department of Neurology, Prince Henry Hospital, Sydney, NSW, Australia.
P J
PJ
Goadsby
D000818:Animals; D001784:Blood Gas Analysis; D015740:Calcitonin Gene-Related Peptide / Q000037:antagonists & inhibitors* / Q000494:pharmacology*; D002415:Cats; D002560:Cerebrovascular Circulation / Q000187:drug effects*; D004558:Electric Stimulation; D006439:Hemodynamics / Q000187:drug effects; D010446:Peptide Fragments / Q000494:pharmacology*; D018003:Receptors, Calcitonin; D011956:Receptors, Cell Surface / Q000187:drug effects*; D013238:Stereotaxic Techniques; D014276:Trigeminal Nerve / Q000502:physiology*; D014664:Vasodilation / Q000187:drug effects*
D010446:Peptide Fragments; D018003:Receptors, Calcitonin; D011956:Receptors, Cell Surface; C058636:calcitonin gene-related peptide (8-37); D015740:Calcitonin Gene-Related Peptide