Melatonin, the Pineal Gland, and Circadian Rhythms
Annual rept. 1 Mar 1993-28 Feb 1994
TEXAS A AND M UNIV COLLEGE STATION DEPT OF BIOLOGY
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Pineal melatonin may effect the light sensitivity of rats such that, pineal ectomized rats perceive ambient intensity to be higher than sham-operated controls We have tested this a several ways. Essentially, we can find no evidence that pinealectomized rats are more sensitive to light than are pinealectomized rats. We have found that free-running circadian period lengthens in response to increasing light intensities at the same rate, but that pinealectomized rats become disrupted at lower intensities than do sham-operated animals. Further, our initial observation that enucleation of rats abolishes SCN iodomelatonin binding ahs proven incorrect when we corrected for circadian phase. Pineal melatonin influences circadian system coupling either at the level of coupling among circadian oscillators thenselves or between these oscillators and there multiple outputs.
- Anatomy and Physiology