Effects of opiate agonists and an antagonist on food intake and brain neurotransmitters in normophagic and obese "cafeteria" rats.
The relationship between the effects of opiates on food intake and on central monoamines in various brain areas was investigated in normophagic and obese "cafeteria" rats. Three agonists, beta-endorphin, dynorphin, and D-Ser2-Leu-Enk-Thr6 (DSLET) and an antagonist, naltrexone, were used. The three agonists enhanced feeling in normophagic rats but had different dopaminergic effects. Serotonergic metabolism increased concomitantly with the enhancement of feeding by the agonists, whereas it decreased following treatment with the antagonist naltrexone. In the cafeteria rats, although the feeding effects of dynorphin and DSLET occurred earlier, there was a complete lack of monoaminergic effects. beta-Endorphin was completely devoid of effects in this model. There would, thus, appear to be a positive correlation between the behavioural effects of these opiates and serotonergic metabolism in normophagic rats, while stimulated feeding situations ("cafeteria" rats) the disruption of a monoaminergic modulation does not prohibit a direct effect on feeding.
Robert
J J
JJ
Laboratoire de Pharmacologie, U.A.CNRS 594, Faculté de Pharmacie, Châtenay-Malabry.
Orosco
M
M
Rouch
C
C
Jacquot
C
C
Cohen
Y
Y
D000818:Animals; D015306:Biogenic Monoamines / Q000378:metabolism* / Q000502:physiology; D001921:Brain / Q000187:drug effects / Q000378:metabolism*; D004298:Dopamine / Q000378:metabolism / Q000502:physiology; D004723:Endorphins / Q000494:pharmacology / Q000502:physiology*; D005247:Feeding Behavior / Q000187:drug effects*; D005260:Female; D009271:Naltrexone / Q000494:pharmacology; D009765:Obesity / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D011957:Receptors, Opioid / Q000187:drug effects / Q000502:physiology*; D012701:Serotonin / Q000378:metabolism / Q000502:physiology
D015306:Biogenic Monoamines; D004723:Endorphins; D011957:Receptors, Opioid; D012701:Serotonin; D009271:Naltrexone; D004298:Dopamine