title: Effects of "Bioactive" amino acids leucine, glutamate, arginine and tryptophan on feed intake and mRNA expression of relative neuropeptides in broiler chicks.
abstract: Feed intake control is vital to ensuring optimal nutrition and achieving full potential for growth and development in poultry. The aim of the present study was to investigate the effects of L-leucine, L-glutamate, L-tryptophan and L-arginine on feed intake and the mRNA expression levels of hypothalamic Neuropeptide involved in feed intake regulation in broiler chicks. Leucine, glutamate, tryptophan or arginine was intra-cerebroventricularly (ICV) administrated to 4d-old broiler chicks respectively and the feed intake were recorded at various time points. Quantitative PCR was performed to determine the hypothalamic mRNA expression levels of Neuropeptide Y (NPY), agouti related protein (AgRP), pro-opiomelanocortin (POMC), melanocortin receptor 4 (MC4R) and corticotrophin releasing factor (CRF). Our results showed that ICV administration of L-leucine (0.15 or 1.5  μmol) significantly (P < 0.05) increased feed intake up to 2 h post-administration period and elevated both hypothalamic NPY and AgRP mRNA expression levels. In contrast, ICV administration of L-glutamate (1.6  μmol) significantly (P < 0.05) decreased feed intake 0.25, 0.5 and 2 h post-injection, and increased hypothalamic CRF and MC4R mRNA expression levels. Meanwhile, both L-tryptophan (10 or 100  μg) and L-arginine (20 or 200  μg) had no significant effect on feed intake. These findings suggested that L-leucine and L-glutamate could act within the hypothalamus to influence food intake, and that both orexigenic and anorexigenic Neuropeptide genes might contribute directly to these effects.
authors.affiliation: College of Animal Sciences, South China Agricultural University, Guangzhou, 510642, P. R. China.
authors.forename: Songbo
authors.initials: S
authors.lastname: Wang
authors.affiliation: College of Animal Sciences, South China Agricultural University, Guangzhou, 510642, P. R. China.|School of Natural Sciences, Department of Biological Sciences, University of Zambia, P.O. Box 32379, Lusaka, Zambia.
authors.forename: Paul
authors.initials: P
authors.lastname: Khondowe
authors.affiliation: College of Animal Sciences, South China Agricultural University, Guangzhou, 510642, P. R. China.
authors.forename: Shengfeng
authors.initials: S
authors.lastname: Chen
authors.affiliation: College of Animal Sciences, South China Agricultural University, Guangzhou, 510642, P. R. China.
authors.forename: Jianjian
authors.initials: J
authors.lastname: Yu
authors.affiliation: College of Animal Sciences, South China Agricultural University, Guangzhou, 510642, P. R. China.
authors.forename: Gang
authors.initials: G
authors.lastname: Shu
authors.affiliation: College of Animal Sciences, South China Agricultural University, Guangzhou, 510642, P. R. China.
authors.forename: Xiaotong
authors.initials: X
authors.lastname: Zhu
authors.affiliation: College of Animal Sciences, South China Agricultural University, Guangzhou, 510642, P. R. China.
authors.forename: Lina
authors.initials: L
authors.lastname: Wang
authors.affiliation: College of Animal Sciences, South China Agricultural University, Guangzhou, 510642, P. R. China.
authors.forename: Ping
authors.initials: P
authors.lastname: Gao
authors.affiliation: College of Animal Sciences, South China Agricultural University, Guangzhou, 510642, P. R. China.
authors.forename: Qianyun
authors.initials: Q
authors.lastname: Xi
authors.affiliation: College of Animal Sciences, South China Agricultural University, Guangzhou, 510642, P. R. China.
authors.forename: Yongliang
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: College of Animal Sciences, South China Agricultural University, Guangzhou, 510642, P. R. China.
authors.forename: Qingyan
authors.initials: Q
authors.lastname: Jiang