Daily patterns of running wheel activity in male anophthalmic mice

Author(s): Ottenweller, J. E.

Journal/Book: Physiol Behav. 1998; 64: The Boulevard, Langford Lane, Kidlington, Oxford OX5 1GB, England. Pergamon-Elsevier Science Ltd. 165-171.

Abstract: Circadian rhythms are generated by the suprachiasmatic nuclei (SCN) and synchronized (entrained) to environmental light-dark cycles by the retinohypothalamic tract (RHT), a direct pathway from the retina to the suprachiasmatic nuclei. In anophthalmic mice, the optic primordia are resorbed between embryonic days 11.5 and 13, before retinal ganglion cells emerge. Thus the retinohypothalamic tract, which is the primary ''zeitgeber'' for circadian rhythms in sighted animals, never forms, and there is no retinal or photic input to the circadian system. We have used wheel running activity, a highly consistent and reliable measure of circadian rhythmicity in rodents, to establish the properties of endogenous locomotor rhythms of anophthalmic mice. We have identified three subpopulations of anophthalmic mice: a) rhythmic with strong stable circadian period but significantly increased period length; b) rhythmic with unstable circadian period; and c) arryhthmic. Future correlation of locomotor rhythms with properties of the suprachiasmatic nuclei in these mice will clarify the relationship between generation and properties of circadian rhythms and the neuroanatomical, neurochemical, and molecular organization of the circadian clock.

Note: Article Laemle LK, Univ Med & Dent New Jersey, New Jersey Med Sch, Dept Anat Cell Biol & Injury Sci, 185 S Orange Ave, Newark,NJ 07103 USA

Keyword(s): circadian rhythms; anophthalmic mice; wheel running; VASOACTIVE INTESTINAL POLYPEPTIDE; LATERAL GENICULATE-NUCLEUS; SUPRACHIASMATIC NUCLEUS; HYPOTHALAMIC CONNECTIONS; CIRCADIAN-RHYTHMS; NEUROPEPTIDE-Y; RAT; IMMUNOREACTIVITY; PHASE; LESIONS

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