Food intake increased after injection of adrenaline into the median raphe nucleus of free-feeding rats.
The present study examined the effects of local injections of adrenaline (AD) or noradrenaline (NA) in equimolar doses (6, 20, and 60 nmol) into the median raphe nucleus (MRN) on ingestive and non-ingestive behaviors of free-feeding rats. The results showed that the treatment with AD at doses of 20 and 60 nmol increased food intake. While the hyperphagic response evoked by 60 nmol dose of AD was accompanied by a reduction of the latency to start feeding and an increase in the frequency of feeding, the 20 nmol dose of AD was unable to change these behavioral aspects of feeding response. The meal size and non-ingestive behaviors were not affected by AD treatment in the MRN. While water intake remained unchanged after the treatment with 20 nmol of AD in the MRN, this dose decreased the latency to start drinking. Feeding and drinking behaviors were not affected by treatment with NA in the MRN. These data suggest that adrenergic receptors of MRN participate in mechanisms that control food intake initiation or appetite. In addition, our results also indicate that the availability of energetic substrate could affect the adrenergic influence on MRN neurons since previous data indicated that the injection of AD into the MRN of food restricted rats decreased food intake.
dos Santos
Rúbia Lima Dias
RL
Department of Physiological Sciences-CCB, Centre of Biological Sciences, Federal University of Santa Catarina (UFSC), 88040-970 Florianópolis, SC, Brazil.
Mansur
Samira Schultz
SS
Steffens
Sérgio Murilo
SM
Faria
Moacir Serralvo
MS
Marino-Neto
José
J
Paschoalini
Marta Aparecida
MA
D000322:Adrenergic Agonists / Q000008:administration & dosage / Q000494:pharmacology; D000316:Adrenergic alpha-Agonists / Q000008:administration & dosage / Q000494:pharmacology; D000818:Animals; D004305:Dose-Response Relationship, Drug; D004326:Drinking / Q000187:drug effects / Q000502:physiology; D004327:Drinking Behavior / Q000187:drug effects / Q000502:physiology; D004435:Eating / Q000187:drug effects* / Q000502:physiology; D004837:Epinephrine / Q000008:administration & dosage / Q000494:pharmacology*; D005247:Feeding Behavior / Q000187:drug effects / Q000502:physiology; D009638:Norepinephrine / Q000008:administration & dosage / Q000494:pharmacology; D011903:Raphe Nuclei / Q000187:drug effects* / Q000502:physiology; D051381:Rats; D017208:Rats, Wistar
D000322:Adrenergic Agonists; D000316:Adrenergic alpha-Agonists; D009638:Norepinephrine; D004837:Epinephrine