title: Lateral hypothalamic serotonin is not stimulated during central leptin hypophagia.
abstract: Whether leptin targets the hypothalamic serotonergic system to inhibit food intake is not established. We examined the effect of a short-term i.c.v. leptin treatment on serotonin microdialysate levels in rat lateral hypothalamus. Adipose tissue gene expression was also evaluated. Male rats received four daily injections of leptin (5 μg) or vehicle (with pair-feeding to leptin-induced intake) and a fifth injection during collection of LH microdialysates. We found that serotonin and 5-HIAA levels were not affected by the leptin pre-treatment, as basal levels were similar between the leptin and the pair-fed group. These levels remained unaltered after the acute leptin injection. For gene expression studies, rats were pre-treated with five daily injections of either leptin (5 μg) or vehicle (with either pair-feeding or ad libitum intake). mRNA levels of resistin, adiponectin, lipoprotein lipase, and PPAR-gamma were unaltered by either leptin or pair-feeding. Leptin gene expression was significantly reduced by leptin but not by pair-feeding, in both the retroperitoneal (-74%) and the epididymal (-99%) depots while no differences were observed in the subcutaneous depot. The observations confirmed the absence of an acute stimulatory effect of central leptin on serotonin release in the lateral hypothalamus and showed that the pre-treatment with leptin failed to modify this pattern. This indicates that components of the serotonergic system are probably not directly affected by leptin. Additionally, the central effect of leptin was able to downregulate its own adipose tissue gene expression in a depot-specific manner while other adipokine genes were not affected.
authors.affiliation: Departamento de Fisiologia, Disciplina de Fisiologia da Nutrição, Universidade Federal de São Paulo (UNIFESP), São Paulo/SP, Brazil.
authors.forename: Mônica Marques
authors.initials: MM
authors.lastname: Telles
authors.forename: Thaís Girão
authors.initials: TG
authors.lastname: da Silva
authors.forename: Regina Lúcia Harumi
authors.initials: RL
authors.lastname: Watanabe
authors.forename: Iracema Senna
authors.initials: IS
authors.lastname: de Andrade
authors.forename: Debora
authors.initials: D
authors.lastname: Estadella
authors.forename: Cláudia Maria Oller
authors.initials: CM
authors.lastname: Nascimento
authors.forename: Lila Missae
authors.initials: LM
authors.lastname: Oyama
authors.forename: Eliane Beraldi
authors.initials: EB
authors.lastname: Ribeiro
mesh_terms: D000273:Adipose Tissue / Q000378:metabolism; D000818:Animals; D004435:Eating / Q000187:drug effects* / Q000235:genetics; D015870:Gene Expression; D006897:Hydroxyindoleacetic Acid / Q000378:metabolism; D007031:Hypothalamus / Q000187:drug effects / Q000378:metabolism*; D020738:Leptin / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology*; D008297:Male; D017551:Microdialysis; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D052243:Resistin / Q000235:genetics / Q000378:metabolism; D012701:Serotonin / Q000378:metabolism*
chemical_list: D020738:Leptin; D012333:RNA, Messenger; D052243:Resistin; D012701:Serotonin; D006897:Hydroxyindoleacetic Acid