title: Timed food availability affects circadian behavior but not the neuropeptide Y expression in Indian weaverbirds exposed to atypical light environment.
abstract: We tested the hypothesis whether daily food availability period would restore rhythmicity in individuals with disrupted circadian behavior with no effect on appetite regulation. Particularly, we investigated the effects of timed food availability on activity behavior, and Fos and neuropeptide Y expressions in Indian weaverbirds (Ploceus philippinus) under atypical light conditions. Initially, weaverbirds in 3 groups of 7-8 each were entrained to 7L:17D (25: <0.3lx) with food ad libitum. Thereafter, food availability was restricted for 7h such that it overlapped with the light period. After a week, 7L:17D was replaced with 3.5L: 3.5D (T7, group 1), 3.5L: 20.5D (T24, group 2) or constant dim light, LLdim (<0.3lx, group 3) for 5weeks. Food cycles synchronized the circadian activity behavior, albeit with group differences, but did not affect body mass, blood glucose levels or testis size. Further, Fos, not NPY mRNA or peptide, expression measured at ZT2 and ZT14 (ZT0=time of food given) showed significant group differences in the hippocampus, dorsomedial hypothalamus and infundibular nuclear complex. Another identical experiment examined after-effects of the 3 light conditions on persistence of the circadian rhythms. Weaverbirds exposed for 4weeks to identical food but different light conditions, as above, were released into the free-running condition of food ad libitum and LLdim. Circadian rhythms were decayed in birds previously exposed to T7 LD cycle. Overall, these results show that timed meal restores rhythmicity in individuals with circadian rhythm disruptions without involving neuropeptide Y, the key appetite regulatory molecule.
authors.affiliation: IndoUS Center for Biological Timing, Department of Zoology, University of Delhi, Delhi 110 007, India.
authors.forename: Devraj
authors.initials: D
authors.lastname: Singh
authors.affiliation: Department of Zoology, University of Lucknow, Lucknow, 226 007, India.
authors.forename: Neerja
authors.initials: N
authors.lastname: Trivedi
authors.affiliation: Department of Zoology, University of Lucknow, Lucknow, 226 007, India.
authors.forename: Shalie
authors.initials: S
authors.lastname: Malik
authors.affiliation: Department of Zoology, University of Lucknow, Lucknow, 226 007, India.
authors.forename: Sangeeta
authors.initials: S
authors.lastname: Rani
authors.affiliation: IndoUS Center for Biological Timing, Department of Zoology, University of Delhi, Delhi 110 007, India. Electronic address: drvkumar11@yahoo.com.
authors.forename: Vinod
authors.initials: V
authors.lastname: Kumar
mesh_terms: D000818:Animals; D001069:Appetite Regulation / Q000502:physiology*; D001921:Brain / Q000378:metabolism; D002940:Circadian Rhythm / Q000502:physiology*; D005260:Female; D005502:Food; D005786:Gene Expression Regulation / Q000502:physiology* / Q000528:radiation effects; D008027:Light; D008297:Male; D009043:Motor Activity / Q000502:physiology; D009478:Neuropeptide Y / Q000235:genetics / Q000378:metabolism*; D016761:Oncogene Proteins v-fos / Q000235:genetics / Q000378:metabolism; D011247:Pregnancy; D012333:RNA, Messenger / Q000378:metabolism; D020308:Songbirds / Q000502:physiology; D018709:Statistics, Nonparametric
chemical_list: D009478:Neuropeptide Y; D016761:Oncogene Proteins v-fos; D012333:RNA, Messenger
keywords: DMH; Food cycle; Fos; Infundibular nuclear complex; LD cycle; Neuropeptide Y