Accession Number : ADA320991

Title :   Cell Culture and Transplantation of the Suprachiasmatic Circadian Pacemaker.

Descriptive Note : Final rept. 30 Sep 92-29 Sep 95,

Corporate Author : TORONTO UNIV (ONTARIO) DEPT OF PSYCHOLOGY

Personal Author(s) : Ralph, Martin R.

PDF Url : ADA320991

Report Date : SEP 1995

Pagination or Media Count : 9

Abstract : Circadian activity rhythms that have been eliminated by lesions of the suprachiasmatic nucleus (SCN) can be restored by fetal SCN grafts. Partial lesions of the host allow simultaneous expression of both donor and host rhythm. Because partial SCN ablation produces characteristic changes in activity rhythms that are similar to those that occur with age, including shortened period, reduced amplitude, and fragmentation, we investigated the extent to which fetal SCN grafts may be expressed by an animal whose activity rhythm exhibits these age-dependent changes. The result indicate that expression of a transplanted clock is possible in an unlesioned aged host. Crafts of fetal SCN into young hosts and cortical tissue grafts into intact aged hosts have no effect. In those aged animals that received SCN grafts, three patterns of expression emerged in the subsequent locomotor activity record: complete dominance of locomotor rhythmicity by donor; relative coordination between donor and host rhythms; and spontaneous switching between host and donor phenotypes. The results suggest that the expression of rhythmicity by the grafted SCN may depend on the relative amplitude or strength of signals produced by the host and donor SCN.

Descriptors :   *CIRCADIAN RHYTHMS, *SURGICAL TRANSPLANTATION, *BIOLOGICAL RHYTHMS, CLOCKS, FRAGMENTATION, REDUCTION, SIGNALS, PATTERNS, ANIMALS, SYNCHRONISM, AMPLITUDE, CELLS(BIOLOGY), CULTURES(BIOLOGY), LESIONS, SKIN GRAFTS, LOCOMOTION.

Subject Categories : Anatomy and Physiology

Distribution Statement : APPROVED FOR PUBLIC RELEASE