Oral Presentation Australian & New Zealand Obesity Society 2015 Annual Scientific Meeting

Entrainability of circadian rhythms in gastric vagal afferent satiety signals by restricted food access (#38)

Stephen J Kentish 1 2 , George Hatzinikolas 1 , Hui Li 1 , Claudine L Frisby 1 , Gary A Wittert 1 2 , Amanda J Page 1 2 3
  1. Discipline of Medicine, University of Adelaide, Adelaide, SA, Australia
  2. South Australian Health and Medical Research Institute, Adelaide, SA, Australia
  3. Royal Adelaide Hospital, Adelaide, SA, Australia

 Mechanosensitive gastric vagal afferents (GVAs) are part of a coordinated set of mechanisms involved in the regulation of food intake. GVAs exhibit circadian variation in their response to mechanical stimuli allowing time of day specific satiety signalling1. This circadian variation is ablated by 12wks ad libitum access to a high fat diet (HFD). It is unclear whether the circadian pattern is entrainable to restricted food access.

We fed 8wk male C57BL/6 mice a standard diet (SLD; 18%kJ from fat) or a HFD (60%kJ from fat) ad libitum for 4wks, then each dietary group was divided so that half had access to food only during the light phase (LP:07:00-19:00) or dark phase (DP:19:00-07:00) for 8wks. From each group 8 mice were housed in metabolic cages to collect feeding data over the 12wks. Mice were  sacrificed at 3hr intervals from 07:00 and recordings from GVA tension and mucosal receptors were taken2.

After 12wks both HFD groups weighed more than the SLD groups with no difference between LP and DP mice on the same diet. SLD-DP mice consumed more daily food through increased meal number (vs SLD and HFD LP mice) and meal size (vs HFD-DP). 24hr energy consumption was no different between SLD-DP, HFD-DP and HFD-LP mice. In SLD and HFD-DP mice, at 01:00 compared to 13:00 the response of tension receptors to 3g tension were reduced by 73% and 69% respectively. Mucosal receptor response to stroking (50mg) was reduced by 66% and 64% respectively. LP fed mice showed reversed circadian rhythms with 78%(SLD) and 59%(HFD) reductions in the tension response to tension and 65%(SLD) and 70%(HFD) reductions mucosal stroking at 13:00 compared to 01:00.

Circadian rhythms in GVA satiety signals can be entrained to a period of food access to largely maintain caloric intake. This entrainment is unaffected by HFD feeding.

  1. Kentish SJ, Frisby CL, Kennaway DJ, Wittert GA, Page AJ (2013) Circadian variation in gastric vagal afferent mechanosensitivity. J Neurosci 33:19238-19242.
  2. Page AJ, Martin CM, Blackshaw LA (2002) Vagal mechanoreceptors and chemoreceptors in mouse stomach and esophagus. Journal of neurophysiology 87:2095-2103.