Identification of central projections from amylin-activated neurons to the lateral hypothalamus.
The ability of the pancreatic hormone amylin to inhibit food intake relies on a direct activation of the area postrema (AP). This activation is synaptically transmitted to the nucleus of the solitary tract (NTS), the lateral parabrachial nucleus (LPB), the central amygdaloid nucleus (Ce) and the lateral bed nucleus of stria terminalis (BSTL). Interestingly, neurons of the rostro-dorsal lateral hypothalamic area (dLHA), which are activated during fasting, are inhibited by peripheral amylin, although they lack amylin receptors. Using the retrograde tracer cholera toxin-B (Ctb) we analyzed whether the dLHA receives neuronal projections from amylin-activated brain areas. The anterograde tracer biotinylated dextran-amine (BDA) was used to confirm the projections and to identify further neuronal pathways potentially involved in amylin signaling. We identified dense projections from the amylin activated neurons in the LPB and sparse projections from the NTS to the dLHA. LPB fiber efferents were found in close proximity to dLHA nuclei activated by 24h of fasting. The AP and the Ce showed no projections to the dLHA. Dense efferents were also observed from the LPB to other hypothalamic areas, namely to the ventromedial, dorsomedial, paraventricular and arcuate nuclei. This study provides neuroanatomical evidence that among the amylin activated areas, the LPB provides the strongest input to the dLHA, thus it may mediate the amylin-induced inhibition of the dLHA.
Potes
Catarina Soares
CS
Institute of Veterinary Physiology and Zurich Center for Integrative Human Physiology, University of Zurich, 8057 Zurich Switzerland.
Lutz
Thomas Alexander
TA
Riediger
Thomas
T
D000682:Amyloid / Q000494:pharmacology*; D000818:Animals; D001067:Appetite Depressants / Q000494:pharmacology*; D001710:Biotin / Q000031:analogs & derivatives / Q000378:metabolism; D001931:Brain Mapping; D002772:Cholera Toxin / Q000378:metabolism; D003911:Dextrans / Q000378:metabolism; D005786:Gene Expression Regulation / Q000187:drug effects; D007026:Hypothalamic Area, Lateral / Q000166:cytology*; D058228:Islet Amyloid Polypeptide; D008297:Male; D009434:Neural Pathways / Q000502:physiology; D009474:Neurons / Q000187:drug effects* / Q000378:metabolism; D016760:Proto-Oncogene Proteins c-fos / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar
D000682:Amyloid; D001067:Appetite Depressants; D003911:Dextrans; D058228:Islet Amyloid Polypeptide; D016760:Proto-Oncogene Proteins c-fos; C076397:biotinylated dextran amine; D001710:Biotin; D002772:Cholera Toxin