Activation of trigeminovascular neurons by glyceryl trinitrate.
The effect of intra-carotid arterial infusions of glyceryl trinitrate (GTN), a substance known to precipitate headache, including migraine, upon the spontaneous activity of trigeminal neurons with craniovascular input was studied in cats. Second-order craniovascular neurons which received sensory input from the superior sagittal sinus were recorded in the trigeminal nucleus caudalis. Infusions of GTN were administered via a catheter inserted retrogradely into the common carotid artery through the lingual artery. Infusions of GTN (100 microg kg(-1) min(-1) in a volume of 2 ml min(-1)) increased the mean basal discharge rate of all second-order neurons to 239+/-47% of control. GTN produced a fall in mean blood pressure, but there was no correlation between this fall and the changes in discharge rate. GTN infusions sensitised neurons to the effects of electrical stimulation of the superior sagittal sinus, but not to subsequent GTN infusions. Infusions of similar volumes of vehicle did not alter the discharge rate of neurons. We conclude that GTN activates craniovascular sensory pathways at a site at, or peripheral to, the second-order neuron and that such an action may account for at least the acute-onset headache induced by GTN.
Lambert
G A
GA
Institute of Neurological Sciences, The Prince Henry and Prince of Wales Hospitals, University of New South Wales, NSW 2036, Little Bay, Australia. g.lambert@unsw.edu.au
Donaldson
C
C
Boers
P M
PM
Zagami
A S
AS
D000818:Animals; D001794:Blood Pressure / Q000187:drug effects / Q000502:physiology; D017536:Carotid Artery, Common / Q000187:drug effects* / Q000502:physiology; D002415:Cats; D004388:Dura Mater / Q000187:drug effects / Q000502:physiology; D004558:Electric Stimulation; D005260:Female; D006261:Headache / Q000503:physiopathology; D006339:Heart Rate / Q000187:drug effects / Q000502:physiology; D008297:Male; D009475:Neurons, Afferent / Q000187:drug effects* / Q000502:physiology; D005996:Nitroglycerin / Q000494:pharmacology*; D014276:Trigeminal Nerve / Q000187:drug effects / Q000502:physiology; D014278:Trigeminal Nuclei / Q000187:drug effects* / Q000502:physiology; D014665:Vasodilator Agents / Q000494:pharmacology*
D014665:Vasodilator Agents; D005996:Nitroglycerin