Differential role of the hippocampus, amygdala, and dorsal raphe nucleus in regulating feeding, memory, and anxiety-like behavioral responses to ghrelin.
Ghrelin is a peptide hormone produced and secreted from the stomach. Hypothalamic injection of the peptide increases food intake but it is not known if the peptide affects other brain regions. We measured several behavioral parameters such as anxiety (elevated plus maze), memory retention (step down test), and food intake after injections of different doses of the peptide in the hippocampus, amygdala, and dorsal raphe nucleus (DRN). The injection of ghrelin in the hippocampus and DRN significantly and dose dependently increased food intake in relation to controls rats, while injections into the amygdala did not affect the food intake. We also show for the first time that ghrelin clearly and dose dependently increases memory retention in the hippocampus, amygdala, and DRN. Moreover, ghrelin at different potencies induced anxiogenesis in these brain structures while the highest dose of 3 nmol/microl was effective in all of them. The comparison of sensitivity of each brain structure indicates a specific role of them for each of the behaviors studied. The results provide new insight in to the anatomical substrate and the functional role of extrahypothalamic ghrelin targets in the CNS.
Carlini
Valeria P
VP
Departamento de Farmacología, Facultad de Ciencias Químicas, UNC, Córdoba, Argentina.
Varas
Mariana M
MM
Cragnolini
Andrea B
AB
Schiöth
Helgi B
HB
Scimonelli
Teresa N
TN
de Barioglio
Susana R
SR
D000679:Amygdala / Q000502:physiology*; D000818:Animals; D001522:Behavior, Animal; D004305:Dose-Response Relationship, Drug; D005247:Feeding Behavior; D054439:Ghrelin; D006624:Hippocampus / Q000502:physiology*; D008297:Male; D018782:Maze Learning; D008568:Memory; D036361:Peptide Hormones / Q000378:metabolism / Q000502:physiology*; D010455:Peptides / Q000737:chemistry; D011903:Raphe Nuclei / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar; D013379:Substrate Specificity; D013997:Time Factors
D054439:Ghrelin; D036361:Peptide Hormones; D010455:Peptides