A neuroendocrinological study on the mechanism of activation of neurotransmitter by mastication

1999 Fiscal Year Final Research Report Summary

• Project/Area Number: 10671920
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: 矯正・小児・社会系歯学
• Research Institution: Kagoshima University (1999); Hokkaido University (1998)
• Principal Investigator: YOSHIHARA Toshihiro Kagoshima University, Dental Hospital, Assistant Professor, 歯学部・附属病院, 講師 (60261319)
• Project Period (FY): 1998 – 1999
• Keywords: mastication / learning / memory / neuropeptide Y / rat

Research Abstract

Effects of mastication were examined on the learning and memory in rats. The following result was obtained.
(1) In Hebb and Williams' maze test, twenty-four Wistar rats were divided into four groups: rats which were fed normal solid meal (Solid Rats), liquid meal (Liquid Rats), intravenous hyperalimentation through jugular vein (IH Rats) or liquid meal infusion through cardiac part of stomach (LMI Rats). The total error score of the Solid Rats were significantly less than that of the Liquid Rats. The total error score of the Liquid Rats were significantly less than those of the IH Rats and the LMI Rats. There was no significant difference of the total error scores between IH Rat and LMI Rat.
(2) Neuropeptide Y (NPY) concentrations in hypothalamus (paraventricular nucleus and arcuate nucleus) of the above-mentioned rats were measured. NPY concentration in Solid Rat was significantly higher than that in Liquid Rat. And NPY concentration in Liquid Rat was significantly higher than that in IH Rat and LMI Rat. There was no significant difference of NPY concentration between IH Rat and LMI Rat.
These results suggest that food intake through mouth, particularly with mastication, is important for development of ability of learning in rats and that NPY is involved in this mechanism of development.