Behavioural and electroencephalographic effects of systemic injections of 8-OH-DPAT in the pigeon (Columba livia).
The effects of systemic injections of the 5HT(1A) receptor agonist 8-OH-DPAT on the spontaneous ingestive, maintenance, locomotor and sleep-like behaviours, and the sleep/waking-related hippocampal electrographic activity were investigated in pigeons. 8-OH-DPAT (0.06, 0.2, 0.6 or 2.0mg/kg) was found to dose-dependently reduce food and water intake, acutely (in the first 3h) and 24h after treatment, during both low-activity morning hours (starting at 10:00 h) and high-activity evening hours (starting at 14:00 h). Automated 24h records of food and water intake indicated that hypophagic effects can last up to 18 h after injection. Duration and incidence of sleep-like postures increased at all doses, in both morning and afternoon. These effects were associated with decreases in exploratory and preening activities. The 8-OH-DPAT-induced hypnogenic, hypophagic and hypodipsic effects tended to be more intense in the morning than in the afternoon-trials. Pretreatment with WAY 100635 (a 5-HT(1A) antagonist; 0.6 mg/kg) eliminated all of these 8-OH-DPAT-induced effects. WAY 100635 failed to affect feeding when injected alone, but decreased frequency of sleep-like responses and increased the latency to the first sleep-like episode. Hippocampal EEG tracings after 8-OH-DPAT injections (0.6 or 2.0mg/kg) indicated that the hypnogenic effects are associated with a specific increase in the frequency and duration of slow wave sleep. Power density analysis of the hippocampal EEG failed to show differences between 8-OH-DPAT-induced sleep and the sleep occurring after vehicle injections, indicating that it may be electrographically similar to diurnal sleep episodes in the pigeon. These data suggest that while 5-HT(1a) receptor-mediated mechanisms play crucial roles in ingestive and sleep/waking behaviours in mammals and birds, their action upon these states shows substantial inter-taxon variance.
Dos Santos
Murilo Marcos
MM
Laboratory of Comparative Neurophysiology, Department of Physiological Sciences, CCB, Federal University of Santa Catarina, Florianópolis 88049-900, SC, Brazil. murilomsantos@pop.com.br
Hoeller
Alexandre Ademar
AA
dos Santos
Tiago Souza
TS
Felisbino
Manuela Brisot
MB
Herdt
Marcello Alberton
MA
da Silva
Eduardo Simão
ES
Paschoalini
Marta Aparecida
MA
Marino-Neto
José
J
D017371:8-Hydroxy-2-(di-n-propylamino)tetralin / Q000008:administration & dosage*; D000704:Analysis of Variance; D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects*; D002940:Circadian Rhythm / Q000187:drug effects*; D010856:Columbidae; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D004569:Electroencephalography / Q000187:drug effects; D005106:Exploratory Behavior / Q000187:drug effects; D005247:Feeding Behavior / Q000187:drug effects*; D005260:Female; D006624:Hippocampus / Q000187:drug effects*; D007273:Injections, Intramuscular; D008297:Male; D009043:Motor Activity / Q000187:drug effects; D010879:Piperazines / Q000494:pharmacology; D011725:Pyridines / Q000494:pharmacology; D012702:Serotonin Antagonists / Q000494:pharmacology; D017366:Serotonin Receptor Agonists / Q000008:administration & dosage*; D012890:Sleep / Q000187:drug effects; D018709:Statistics, Nonparametric; D013997:Time Factors
D010879:Piperazines; D011725:Pyridines; D012702:Serotonin Antagonists; D017366:Serotonin Receptor Agonists; C090413:N-(2-(4-(2-methoxyphenyl)-1-piperazinyl)ethyl)-N-(2-pyridinyl)cyclohexanecarboxamide; D017371:8-Hydroxy-2-(di-n-propylamino)tetralin