| Co-Investigator(Kenkyū-buntansha) |
OOKA Sadako ATOMI JUNIOR COLLEGE,DEPARTMENT OF BIOOLOGY,ASSISTANT PROFESSOR (PART TIME), 短期大学部, 非常勤講師
ATOBE Yoshitoshi YOKOHAMA CITY UNIVERSITY SCHOOL OF MEDICINE,DEPARTMENT OF ANATOMY,INSTRUCTOR, 医学部, 助手 (60264602)
FUNAKOSHI Kengo YOKOHAMA CITY UNIVERSITY SCHOOL OF MEDICINE,DEPARTMENT OF ANATOMY,ASSISTANT PROF, 医学部, 講師 (60291572)
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| Research Abstract |
The hagfish, a cyclostome, is one of the most primitive vetebrates, so that a study of its circadian rythm of locomotor activity (biological clock) is interesting from the standpoint of phylogeny. In vertebrates, the suprachiasmatic nucleus in the hypothalamus and the pineal gland have been reported to be locations of the circadian pacemaket However, the hagfish is reported to lack a pineal gland, and a suprachiasmatic nucleus has not been detected in the hypothalamus. The chemoarchitectonics of the posterior part of the preoptic nucleus, which might be the circadian pacemaker for the locomotor activity of the hagfisli, Eptatretus burgeri, was immunohistochemically and enzyme histochemically investigated. Relatively large to medium size perikaya containing arginine-vasopressin (AV), leucine-enkephalin, and substance P (SP) immunoreactivity were distributed in it. Small perikaya, probably intrinsic neurons, containing NADPH diaphorase activity and nitric oxide synthase + were also distributed in it. There were also nerve fibers containing AV, LENK, SP, Neuropeptide Y, FMRF-amide, serotonin, and dopamine immunoreactivity. Rhodopsin (a histological marker of the extra-retinal light perception) immunoreactive structures in the brain could not be found. The retinal projection to the preoptic nucleus, which was investigated by HRP tracing, showed HRP-labeled varicose fibers distriluted in it (light microscopically) but HRP labeled synapses could not be found. The relationship between the light and circadian rhythm of locomotor activity was behaviorally investigated.
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