Differential motor and blood pressure effects of intrathecal oxytocin and TRH in the rat.
While previous reports have immunocytochemically localized oxytocin and TRH in the spinal cord, the functional significance of these peptides is unclear. The present paper examined this issue and tested the effects of these peptides upon intrathecal administration. We found both peptides produced lasting motor and blood pressure changes. Oxytocin elicited prolonged jerks of the hindlimbs and the tail, while TRH produced an increase of hindlimb muscle tone and tail tremor. TRH in larger doses (5, 10 micrograms) also caused tail erections and whipping. The motor effects of both peptides were dose-dependent. Intrathecal oxytocin (0.75 or 1.5 IU) caused a transient drop in blood pressure followed by a rise, in 4 out of 7 rats. The other 3 only showed a hypertensive effect. In contrast, intrathecal TRH produced a rise in blood pressure in all the animals tested. These findings suggest that both oxytocin and TRH may play a role in the regulation of motor and automatic functioning at the spinal level.
D000818:Animals; D001794:Blood Pressure / Q000187:drug effects*; D006973:Hypertension / Q000139:chemically induced; D007278:Injections, Spinal; D007700:Kinetics; D008297:Male; D009043:Motor Activity / Q000187:drug effects*; D010121:Oxytocin / Q000008:administration & dosage / Q000494:pharmacology*; D051381:Rats; D013973:Thyrotropin-Releasing Hormone / Q000008:administration & dosage / Q000494:pharmacology*
D010121:Oxytocin; D013973:Thyrotropin-Releasing Hormone