title: Leptin receptor of the hind brain nuclei is involved in the conditioned taste preference of rats.
abstract: OBJECTIVE
  Conditioned taste preference (CTP) is a taste learning reflex by which an animal learns to prefer a substance which tastes not well and has been studied with much interest in recent years. However, the neural substrates of CTP are less known. This study aimed to determine the possible neural path- ways of CTP and whether serum leptin level and the leptin receptor (OB-Rb) in the hind brain are involved following CTP formation.
  
  
  METHODS
  We established CTP of quinine in rats with a 2-bottle preference test. The serum leptin concentrations were detected, the expression of c-fos in the rat brain was tested to determine the nuclei in relation with establishment of CTR Finally, the OB-Rb mRNA expression was examined by RT-qPCR assay in parabrachial nucleus (PBN) and the nucleus of the solitary tract (NST) of the hind brain.
  
  
  RESULTS
  Compared with control group, the level of serum leptin was higher in the CTP group (4.58 ± 0.52 vs 1.67 ± 0.25 µg/L, P < 0.01); increased c-fos positive cells were found in the anterior hypothalamus (AH, 221.75 ± 4.96 vs. 178.50 ± 6.63 cells/mm², P < 0.05), the basal lateral amygdala (BLA, 70.75 ± 6.17 vs 56.50 ± 3.62 cells/ mm², P < 0.05) and the nucleus of the solitary tract (NST, 41.25 ± 1.32 vs 32.50 ± 1.02 cells/mm², P < 0.05). But in ventromedial nucleus of the hypothalamus (VMH, 20.75 ± 2.73 vs 38.5 ± 1.54 per 1 mm², P < 005), PBN (21.50 ± 2.24 vs 36.25 ± 1.49 cells/mm², P < 0.05) and the central nucleus of the amygdala (CeA, 22.25 ± 1.53 vs 35.50 ± 2.11 cells/mm², P < 0.05), the number of c-fos positive cells was decreased in the CTP group. In addition, we found OB-Rb mRNA expression in PBN of CTP group rats was higher than that of control group (0.95 ± 0.055 vs 0.57 ± 0.034, P < 0.05), while there was no significant difference of OB-Rb mRNA expression in NST between the two groups.
  
  
  CONCLUSIONS
  Nuclei AH, BLA, NST, VMH, PBN and CeA participate in the formation of CTP. Leptin and its receptor in PBN may be involved in the formation and maintenance of CTP.
authors.forename: Cai-xia
authors.initials: CX
authors.lastname: Lin
authors.forename: Shao-yun
authors.initials: SY
authors.lastname: Zhang
authors.forename: Ke
authors.initials: K
authors.lastname: Chen
authors.forename: Xiao
authors.initials: X
authors.lastname: Luo
authors.forename: Bo
authors.initials: B
authors.lastname: Sun
authors.forename: Yu-ming
authors.initials: YM
authors.lastname: Kang
authors.forename: Jian-qun
authors.initials: JQ
authors.lastname: Yan
mesh_terms: D000818:Animals; D003213:Conditioning, Psychological; D020738:Leptin / Q000097:blood; D051381:Rats; D054411:Receptors, Leptin / Q000502:physiology*; D012249:Rhombencephalon / Q000502:physiology*; D013649:Taste / Q000502:physiology*
chemical_list: D020738:Leptin; D054411:Receptors, Leptin