Intracerebroventricular galanin-like peptide induces different brain activation compared with galanin.
Like galanin, the 60-amino-acid peptide, galanin-like peptide (GALP), has orexigenic actions, demonstrated by an acute increase in feeding after central injection in rodents. However, in contrast to galanin, GALP causes a prolonged rise in core body temperature and a reduction in body weight over 24 h. In an attempt to identify potential explanations for the observed differences between GALP and galanin, this study examined which brain areas were activated by these peptides. Intracerebroventricular injection of GALP into conscious rats significantly stimulated feeding over 0-1 h, increased core body temperature, but reduced body weight gain over 24 h. Immunohistochemistry to detect c-fos demonstrated that intracerebroventricular injection of GALP or galanin activated several brain regions in common, including the dorsomedial nucleus of the hypothalamus, lateral hypothalamus, and nucleus tractus solitarius of the brainstem. However, GALP also induced c-fos expression in the periventricular hypothalamic region and supraoptic hypothalamic nucleus. Cell activation induced by GALP in the supraoptic hypothalamic nucleus and nucleus tractus solitarius was dependent on food intake but independent of food consumption in all other brain regions. Double immunohistochemistry indicated that small cells expressing c-fos in the periventricular hypothalamic region after GALP were astrocytes and not microglia.
Lawrence
Catherine B
CB
School of Biological Sciences, University of Manchester, Oxford Road, Manchester M13 9PT, United Kingdom.
Williams
Torrie
T
Luckman
Simon M
SM
D000818:Animals; D001253:Astrocytes / Q000378:metabolism; D001831:Body Temperature / Q000187:drug effects; D001835:Body Weight / Q000187:drug effects; D004435:Eating / Q000187:drug effects; D004805:Ependyma / Q000166:cytology / Q000187:drug effects / Q000502:physiology; D019004:Galanin / Q000494:pharmacology*; D044089:Galanin-Like Peptide; D007032:Hypothalamus, Anterior / Q000166:cytology / Q000187:drug effects* / Q000502:physiology; D007150:Immunohistochemistry; D007276:Injections, Intraventricular; D008297:Male; D017628:Microglia / Q000378:metabolism; D009419:Nerve Tissue Proteins / Q000494:pharmacology*; D016760:Proto-Oncogene Proteins c-fos / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D017552:Solitary Nucleus / Q000166:cytology / Q000187:drug effects / Q000502:physiology
D044089:Galanin-Like Peptide; D009419:Nerve Tissue Proteins; D016760:Proto-Oncogene Proteins c-fos; D019004:Galanin