RT Journal Article
SR Electronic
T1 Targeted Microlesions Reveal Novel Organization of the Hamster Suprachiasmatic Nucleus
JF The Journal of Neuroscience
JO J. Neurosci.
FD Society for Neuroscience
SP 2449
OP 2457
DO 10.1523/JNEUROSCI.5323-03.2004
VO 24
IS 10
A1 Lance J. Kriegsfeld
A1 Joseph LeSauter
A1 Rae Silver
YR 2004
UL http://www.jneurosci.org/content/24/10/2449.abstract
AB The role of the suprachiasmatic nuclei (SCN) in generating circadian rhythms in physiology and behavior is well established. Recent evidence based on clock gene expression indicates that the rodent SCN are composed of at least two functional subdivisions. In Syrian hamsters (Mesocricetus auratus), cells in a subregion of the caudal SCN marked by calbindin-D28K (CalB) express light-induced, but not rhythmic, clock genes (Per1, Per2, and Per3). In the SCN region marked by vasopressinergic cells and fibers, clock gene expression is rhythmic. Importantly, lesions of the CalB subregion that spare a significant portion of the SCN abolish rhythms in locomotor behavior. One possibility is that the CalB subregion is required to maintain SCN function necessary to support all behavioral and physiological rhythms. Alternatively, this subregion may control circadian rhythms in locomotor behavior, whereas other circadian responses in physiology and behavior are sustained by different SCN compartments. The present study sought to distinguish between these possibilities by examining the role of the CalB subregion in a battery of rhythms within an individual animal. The results indicate that lesions of the CalB subregion of the SCN abolish circadian rhythms in behavior (locomotion, drinking, gnawing), physiology (body temperature, heart rate), and hormone secretion (melatonin, cortisol), even when other SCN compartments are spared. Together, these findings suggest a novel fundamental property of SCN organization, with a subset of cells being critical for the maintenance of SCN function manifest in circadian rhythms in physiology and behavior.