Intrathecal alpha-trinositol facilitates the flexor reflex but does not block the depressive effect of neuropeptide Y.
We have studied the effects of alpha-trinositol (D-myo-inositol-1,2,6-trisphosphate, PP56), a putative antagonist of neuropeptide Y receptors, on the nociceptive flexor reflex in decerebrate, spinalized rats after intrathecal and intravenous administration. Intrathecal alpha-trinositol caused strong and prolonged facilitation of the flexor reflex, which was usually associated with an increase in spontaneous motoneuron activity. The reflex depressive effect of intrathecal neuropeptide Y was neither blocked nor reversed by alpha-trinositol. Intravenous alpha-trinositol at low doses had no effect on the flexor reflex and at high dose, reflex facilitation was sometimes observed. It is concluded that alpha-trinositol acts as a spinal excitant and is not an antagonist of the neuropeptide Y receptor in the rat spinal cord.
Xu
X J
XJ
Department of Medical Laboratory Sciences and Technology, Huddinge University Hospital, Karolinska Institute, Sweden.
Wiesenfeld-Hallin
Z
Z
D000818:Animals; D004305:Dose-Response Relationship, Drug; D005260:Female; D007278:Injections, Spinal; D007295:Inositol Phosphates / Q000494:pharmacology*; D009478:Neuropeptide Y / Q000037:antagonists & inhibitors*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012018:Reflex / Q000187:drug effects*; D013116:Spinal Cord / Q000187:drug effects*
D007295:Inositol Phosphates; D009478:Neuropeptide Y; C059368:atrinositol