• Karl Messlinger, Megumi Funakubo, Jun Sato, and Kazue Mizumura.
• Institute of Physiology & Pathophysiology, University of Erlangen-Nürnberg, Universitätsstrasse 17, Erlangen, Germany.
• Headache. 2010 Oct 1; 50 (9): 1449-63.

ObjectiveTo determine whether controlled changes in barometric pressure activate rat spinal trigeminal neurons as a possible animal correlate of headaches.BackgroundChanges in weather accompanied by changes in atmospheric pressure are suggested to trigger primary headaches. Mechanisms that increase neuronal activity in the rat spinal trigeminal nucleus may parallel those that contribute to the generation of headaches.MethodsUrethane anesthetized rats were placed in a climatic chamber, in which the air pressure could be selectively manipulated. The parietal cranial dura mater and the spinal dura mater covering the medulla were exposed. Electrolyte-filled electrodes were introduced into the spinal trigeminal nucleus to record from neurons with receptive fields in facial areas and the cranial dura mater and/or the cornea and/or the temporal muscle. Arterial pressure and heart rate were monitored. The barometric pressure was lowered by 40 hPa during 8 minutes, kept at this level for 8 minutes and returned to the previous level.ResultsDuring lowering of the barometric pressure and the low pressure period a sample of neurons showed increased discharge rates. Group analysis revealed that it was the group of units with receptive fields in the cornea, but not in the dura mater or the temporal muscle, which was significantly activated when the animal was exposed to low atmospheric pressure. Exposure of the cranial dura and opening of the cisterna magna did not prevent an increase in activity. In another sample of units the activity recorded after infusion of the nitric oxide donor sodium nitroprusside did not change under low pressure exposure. Arterial pressure and heart rate changed slightly during barometric pressure changes.ConclusionsWe conclude that distinct neurons in the trigeminal nucleus caudalis, particularly with preferential afferent input from the eye, respond to lowering of atmospheric pressure. Similar mechanisms may contribute to the generation of headaches during changes in weather.© 2010 American Headache Society.

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