Effect of intrathecal proctolin administration on the behaviour evoked by the thyrotrophin-releasing hormone (TRH) analogue (RX 77368) and the indoleamine, TRH, substance P and calcitonin gene-related peptide levels and choline acetyltransferase activity in the rat spinal cord.
The behavioral effects and the biochemical changes produced following either a single or repeated intrathecal injection respectively, of the insect peptide proctolin (Arg-Tyr-Leu-Pro-Thr-OH) have been compared with the effects of a stable analogue of thyrotrophin-releasing hormone (TRH) in rats. Intrathecal proctolin (1-100 micrograms) did not produce any marked behavioural effects on its own, while intrathecal TRH analogue (RX 77368, 0.5 microgram) administration produced wet-dog shakes and forepaw-licking behaviours. Proctolin (10 micrograms) significantly attenuated the wet-dog shake and forepaw-licking behaviours evoked by intrathecal RX 77368 administration when it was given 30 min before, but not when given in combination with RX 77368. Repeated intrathecal proctolin administration (10 micrograms twice daily for 5 days) significantly reduced the 5-hydroxytryptamine (5-HT), 5-hydroxyindoleacetic acid and TRH levels in the ventral, but not in the dorsal, horn of the spinal cord nor in the brainstem, and elevated hypothalamic TRH without affecting plasma free thyroxine levels when compared with values in saline-treated controls. Repeated proctolin injection did not alter substance P levels in any brain region examined, nor did it affect the choline acetyltransferase activity or the calcitonin gene-related peptide-like immunoreactive levels in the ventral horn of the spinal cord, both of which are principally located in motoneurones in this cord region.(ABSTRACT TRUNCATED AT 250 WORDS)
Fone
K C
KC
Department of Physiology and Pharmacology, Queen's Medical Centre, Nottingham University, U.K.
Johnson
J V
JV
Bennett
G W
GW
Marsden
C A
CA
D000818:Animals; D002116:Calcitonin / Q000378:metabolism; D015740:Calcitonin Gene-Related Peptide; D002795:Choline O-Acetyltransferase / Q000378:metabolism*; D004347:Drug Interactions; D006897:Hydroxyindoleacetic Acid / Q000378:metabolism*; D007278:Injections, Spinal; D008297:Male; D009479:Neuropeptides / Q000378:metabolism*; D018377:Neurotransmitter Agents / Q000494:pharmacology*; D009842:Oligopeptides / Q000008:administration & dosage / Q000494:pharmacology*; D011761:Pyrrolidonecarboxylic Acid / Q000031:analogs & derivatives; D051381:Rats; D011919:Rats, Inbred Strains; D012016:Reference Values; D012701:Serotonin / Q000378:metabolism*; D013116:Spinal Cord / Q000187:drug effects / Q000378:metabolism*; D013239:Stereotyped Behavior / Q000187:drug effects*; D013373:Substance P / Q000378:metabolism*; D013973:Thyrotropin-Releasing Hormone / Q000031:analogs & derivatives* / Q000378:metabolism* / Q000494:pharmacology
D009479:Neuropeptides; D018377:Neurotransmitter Agents; D009842:Oligopeptides; D012701:Serotonin; D013373:Substance P; D006897:Hydroxyindoleacetic Acid; C011536:proctolin; D013973:Thyrotropin-Releasing Hormone; C027979:L-pyroglutamyl-L-histidyl-3,3-dimethylprolinamide; D002116:Calcitonin; D002795:Choline O-Acetyltransferase; D015740:Calcitonin Gene-Related Peptide; D011761:Pyrrolidonecarboxylic Acid