Effects of central nervous system free fatty acids, prostaglandins and lysophospholipids on allodynia in a mouse model of orofacial pain

Abstract

The present study was carried out to elucidate how CNS free fatty acids, prostaglandins and lysophospholipids can affect responses to mechanical facial stimulation and allodynia, in a mouse model of orofacial pain. The latter received a facial carrageenan injection, and behavioral responses were recorded after stimulation of the inflamed area using a Von Frey hair filament, delivering a 1.4g force. Intracerebroventricular (i.c.v.) injection of the free fatty acids - oleic acid and arachidonic acid, resulted in significantly decreased responses, i.e. had anti-allodynic effects, compared to vehicle injected and non i.c.v. injected controls. In contrast to this, injection of prostaglandin Es (PGE1, PGE2 and PGE3) or lysophospholipids - lysophosphatidylcholine, lysophosphatidic acid and platelet activating factor (PAF) resulted in increased allodynia after facial carrageenan injection. Injection of the PAF receptor antagonist, ginkgolide B resulted in an anti-allodynic effect. These findings suggest that lipid mediators such as prostaglandins and lysophospholipids are involved in signal transduction process related to nociception in the central nervous system.