Activation of serotonin 5-HT1-receptors decreased gripping-induced immobility episodes in taiep rats.
The taiep rat is a myelin mutant that shows a disorganized sleep-wake cycle and immobility episodes (IEs) when the animals are gripped at the base of the tail. During IEs electroencephalographic recordings show a rapid eye movement (REM) sleep-like pattern. These alterations are quite similar to those reported in narcolepsy-cataplexy. Pharmacologically, systemic administration of alpha(2) adrenoceptor agonists increases gripping-induced IEs, whereas alpha(2) antagonists decrease them. However prazosin, an alpha(1) antagonist, increases gripping-induced IEs. In male 8-month-old taiep rats we have studied the effect of systemic administration of serotonergic autoreceptor agonists and antagonists on gripping-induced IEs. 8-Hydroxy-2-(di-n-propylamino) tetraline hydrobromide (8-OH-DPAT), a 5-HT(1A) agonist, and 3-trifluoromethylphenylpiperazine hydrochloride (TFMPP), a 5-HT(1B) agonist, produce a significant decrease in the frequency and mean duration of IEs. Systemic administration of spiperone and 1-(2-methoxyphenyl)-4[4-(2-phthalimido) butyl]piperazine hydrobromide (NAN-190), 5-HT(1) antagonists, increase IEs and their mean duration. When the specific serotonin antagonist N-[2[4-(2-methoxyphenyl)-1-piperazinyl]ethyl]-N-2-pyridinyl-cyclohexanecarboxamide maleate (WAY 100635, 100 microg/kg) was injected 15 min before 8-OH-DPAT, this specific antagonist reverses the effects caused by the 5-HT(1A) agonist. These results show that serotonergic 5-HT(1)-receptors are involved in the susceptibility of gripping-induced IEs in taiep rats. Similar results have been reported in the food-elicited cataplexy test in narcoleptic dogs.
Ita
Martha L
ML
Instituto de Fisiología, Benemérita Universidad Autónoma de Puebla, Mexico.
Cortés
Ma del Carmen
Mdel C
Valencia
Jaime
J
Eguibar
Jose R
JR
D000818:Animals; D001921:Brain / Q000187:drug effects* / Q000378:metabolism / Q000503:physiopathology; D001923:Brain Chemistry / Q000187:drug effects / Q000502:physiology; D002385:Cataplexy / Q000188:drug therapy* / Q000378:metabolism / Q000503:physiopathology; D004195:Disease Models, Animal; D018737:Hand Strength / Q000502:physiology*; D008297:Male; D009290:Narcolepsy / Q000188:drug therapy* / Q000378:metabolism / Q000503:physiopathology; D051381:Rats; D011922:Rats, Mutant Strains; D044263:Receptors, Serotonin, 5-HT1 / Q000378:metabolism; D012701:Serotonin / Q000378:metabolism; D058825:Serotonin 5-HT1 Receptor Agonists; D012702:Serotonin Antagonists / Q000494:pharmacology; D017366:Serotonin Receptor Agonists / Q000494:pharmacology*; D012895:Sleep, REM / Q000187:drug effects / Q000502:physiology; D009435:Synaptic Transmission / Q000187:drug effects / Q000502:physiology
D044263:Receptors, Serotonin, 5-HT1; D058825:Serotonin 5-HT1 Receptor Agonists; D012702:Serotonin Antagonists; D017366:Serotonin Receptor Agonists; D012701:Serotonin