The adrenaline microinjection into the median raphe nucleus induced hypophagic effect in rats submitted to food restriction regimen.
The effect of the equimolar doses (6, 20 and 60 nmol) of either adrenaline (AD) or noradrenaline (NA) microinjected into the median raphe nucleus (MR) on feeding behavior of food-restricted rats (15 g/day/rat) was investigated. The data indicated that 20 nmol AD microinjection, but not NA, into the MR decreased the animal food intake. This hypophagic effect induced by AD may be ascribed to a feeding bout conclusion (satiation process) and not to any changes in non-ingestive behaviors induced by drug microinjection. Since equimolar doses of NA failed to change the animal feeding behavior, it is possible to say that AD-induced hypophagia may be due to either changes in tonic stimulatory control exerted by endogenous noradrenaline on MR or to AD-beta(2) receptor activation in the MR. We claim that such activation may be much more importantly exerted by adrenaline-containing afferents to MR neurons involved with ingestive behavior than by noradrenergic inputs.
Maidel
Simone
S
Department of Physiological Sciences, Centre of Biological Sciences, Federal University of Santa Catarina, 88.040-900 Florianópolis, SC, Brazil. simonemaidel@uol.com.br
Lucinda
Aparecida Marcia
AM
de Aquino
Vivian W
VW
Faria
Moacir Serralvo
MS
Paschoalini
Marta Aparecida
MA
D000322:Adrenergic Agonists / Q000378:metabolism / Q000494:pharmacology; D000344:Afferent Pathways / Q000187:drug effects / Q000378:metabolism; D000818:Animals; D001066:Appetite / Q000187:drug effects* / Q000502:physiology; D001069:Appetite Regulation / Q000187:drug effects* / Q000502:physiology; D004305:Dose-Response Relationship, Drug; D004837:Epinephrine / Q000378:metabolism / Q000494:pharmacology*; D005508:Food Deprivation / Q000502:physiology*; D008297:Male; D008845:Microinjections; D009638:Norepinephrine / Q000378:metabolism / Q000494:pharmacology; D011149:Pons / Q000187:drug effects / Q000378:metabolism; D011903:Raphe Nuclei / Q000187:drug effects* / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D011943:Receptors, Adrenergic, beta / Q000187:drug effects / Q000378:metabolism
D000322:Adrenergic Agonists; D011943:Receptors, Adrenergic, beta; D009638:Norepinephrine; D004837:Epinephrine