AJP - Regulatory, Integrative and Comparative Physiology, Vol 272, Issue 1 422-R428, Copyright © 1997 by American Physiological Society

ARTICLES

Transplantation of fetal suprachiasmatic nuclei into middle-aged rats restores diurnal Fos expression in host

A. Cai, M. N. Lehman, J. M. Lloyd and P. M. Wise
Department of Physiology, School of Medicine, University of Maryland at Baltimore 21201, USA.

In young animals, the suprachiasmatic nuclei (SCN) of the hypothalamus, which are critical circadian pacemakers, exhibit a light-induced diurnal rhythm in Fos expression. The expression of this immediate-early gene has been used as an index of the activity of the SCN and their ability to respond to external cues that entrain them, such as light. In the present study, we show that by the time rats reach middle age baseline Fos expression increases prematurely during the dark and that light-induced Fos expression is blunted and delayed. We also demonstrate that transplantation of fetal tissue containing the SCN into the third cerebral ventricle of middle-aged rats enables aged hosts to regain the ability to exhibit diurnal patterns of Fos expression that are strikingly similar to those observed in young animals. Our findings lead to the following conclusions: 1) the diurnal pattern of activity of SCN cells is blunted in middle-aged rats, and 2) SCN transplants provide unique signals that enable the cellular systems of the host to regain rhythmic functional capabilities. These results provide new insights into the critical active role that the host plays in restoration of function evoked by the presence of a transplant.

This article has been cited by other articles:

				O. Van Reeth, L. Weibel, E. Olivares, S. Maccari, E. Mocaer, and F. W. Turek Melatonin or a melatonin agonist corrects age-related changes in circadian response to environmental stimulus Am J Physiol Regulatory Integrative Comp Physiol, May 1, 2001; 280(5): R1582 - R1591. [Abstract] [Full Text] [PDF]

				A. Popa-Wagner, B. Fischer, D. Platt, H. Schmoll, and C. Kessler Delayed and Blunted Induction of mRNA for Tissue Plasminogen Activator in the Brain of Old Rats Following Pentylenetetrazole-Induced Seizure Activity J. Gerontol. A Biol. Sci. Med. Sci., May 1, 2000; 55(5): 242B - 248. [Abstract] [Full Text]

				P. M. Wise Neuroendocrine modulation of the "menopause": insights into the aging brain Am J Physiol Endocrinol Metab, December 1, 1999; 277(6): E965 - E970. [Abstract] [Full Text] [PDF]

				H. Li and E. Satinoff Fetal tissue containing the suprachiasmatic nucleus restores multiple circadian rhythms in old rats Am J Physiol Regulatory Integrative Comp Physiol, December 1, 1998; 275(6): R1735 - R1744. [Abstract] [Full Text] [PDF]

				F. C. Davis and N. Viswanathan Stability of circadian timing with age in Syrian hamsters Am J Physiol Regulatory Integrative Comp Physiol, October 1, 1998; 275(4): R960 - R968. [Abstract] [Full Text] [PDF]

				K. Krajnak, M. L. Kashon, K. L. Rosewell, and P. M. Wise Aging Alters the Rhythmic Expression of Vasoactive Intestinal Polypeptide mRNA But Not Arginine Vasopressin mRNA in the Suprachiasmatic Nuclei of Female Rats J. Neurosci., June 15, 1998; 18(12): 4767 - 4774. [Abstract] [Full Text] [PDF]

				A. Cai, K. Scarbrough, D. A. Hinkle, and P. M. Wise Fetal grafts containing suprachiasmatic nuclei restore the diurnal rhythm of CRH and POMC mRNA in aging rats Am J Physiol Regulatory Integrative Comp Physiol, November 1, 1997; 273(5): R1764 - R1770. [Abstract] [Full Text] [PDF]