| Summary: | 博士 === 國立陽明大學 === 生理學研究所 === 103 === Ghrelin is a growth-hormone-releasing acylated peptide isolated from the stomach as an endogenous stimulator for growth hormone secretagogue receptors (GHS-R). An n-octanoyl acid is bound at the serine 3 position to form active ghrelin, and only active ghrelin is able to stimulate the secretion of growth hormone. This highly conserved peptide is primarily produced by cells in the oxyntic glands of the stomach, and is released into the bloodstream. It has recently been speculated that ghrelin regulates food intake and energy balance. In the past 10 years, ghrelin is intensively investigated worldwide. By conjugating to bovine serum albumin or Keyhole limpet hemocyanin, our lab have produced anti-human ghrelin antiserum YJC R7-36, MCC R8-51, YJC R1-19, and anti-rat ghrelin antiserum YJC R13-31 in New Zealand Rabbits. These antiserum were used to establish radioimmunoassay system to measure ghrelin in various types of sample. In studies on Sprague-Dawley rats, the enhancement of ghrelin secretion in fasting condition was confirmed firstly. The experiment on young rats indicated that nonylphenol would inhibit the elevation of serum ghrelin and plasma corticosterone caused by forced-gavage. In studies on hypothyroid rats, plasma ghrelin levels increased but serum IGF-1 levels decreased in hypothyroid rats. These results suggested that the hypothyroid condition is able to interfere ghrelin/GHS-R axis as well as the growth hormone/IGF-1 axis. In the human studies, the elevation of serum ghrelin levels by fasting was found and confirm the usefulness of self-produced antiserum. The following experiment revealed that ordinary sandwich and liquid formula Glucerna SR have similar hunger sense by using ghrelin as an objective hunger index.
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