The acute cardiorespiratory effects of centrally injected arachidonic acid; the mediation of prostaglandin E, D and F.

Arachidonic acid (AA), which is released from synaptic membrane phospholipid by neuroreceptor-initiated activation of phospholipase A, is abundant in the brain and works as a neurotransmitter and/or neuromodulator in the central nervous system. Recently we reported that centrally injected AA generated pressor and hyperventilation effects by activating thromboxane A (TXA) signaling pathway. The present study was designed to investigate the mediation of other metabolites of AA such as prostaglandin (PG) D, PGE and PGF alongside TXA in the AA-evoked cardiorespiratory effects in anaesthetized rats. Intracerebroventricular (i.c.v.) administration of AA caused pressor, bradycardic and hyperventilation responses by increasing pO and decreasing pCO in adult male anaesthetized Sprague Dawley rats. Pretreatment (i.c.v) with different doses of DP/EP prostanoid receptor antagonist, AH6809 or FP prostanoid receptor antagonist, PGF dimethylamine partially blocked the cardiorespiratory and blood gas changes induced by AA. In conclusion, these data plainly report that central PGD, PGE or PGF might mediate, at least partly, centrally administered AA-evoked cardiorespiratory and blood gas responses.