Accession Number : ADA264099


Title :   Melatonin, The Pineal Gland and Circadian Rhythms


Descriptive Note : Annual rept. 1 Mar 92-30 Apr 93,


Corporate Author : TEXAS A AND M UNIV COLLEGE STATION DEPT OF BIOLOGY


Personal Author(s) : Cassone, Vincent M


Full Text : https://apps.dtic.mil/dtic/tr/fulltext/u2/a264099.pdf


Report Date : 30 Apr 1992


Pagination or Media Count : 22


Abstract : Amniote circadian organization derives from the interaction circadian oscillator and photoreceptors located in the hypothalamic suprachiasmatic nuclei (SCN), the pineal gland and the eyes. In mammals, circadian organization is dominated by the SCN which serve as 'master pacemakers' in the control of a wide array of behavioral and physiological rhythms including locomotion, sleep/wake, thermoregulation, cardiovascular function and many endocrine processes. Among the rhythms under SCN control in mammals is the circadian synthesis and secretion of the pineal hormone melatonin which relies on a multi-synaptic pathway via the sympathetic nervous system to maintain and entrain rhythmicity in this hormone. Several studies have indicated that pineal melatonin feeds back on SCN rhythmicity to modulate circadian patterns of activity and other processes. However, the nature and system-level significance of this feed-back is unknown. Recently published work indicates that while pinealectomy does not affect rat circadian rhythms in LD or DD, wheel-running activity rhythms are severely disrupted in LL. These data suggest that either (1) pineal feed back regulates the light sensitivity of the SCN and/or (2) it affects coupling among circadian oscillators within the SCN or between the SCN and its output. Research in our laboratory is currently addressing each of these hypotheses.


Descriptors :   *HORMONES , *CIRCADIAN RHYTHMS , *SENSITIVITY , *PINEAL GLAND , TEST AND EVALUATION , OSCILLATORS , MAMMALS , INTERACTIONS , LIGHT , PATTERNS , MELATONIN , SLEEP , SECRETION , SYMPATHETIC NERVOUS SYSTEM , COUPLINGS , NUCLEI , HYPOTHESES , EYE , TEMPERATURE CONTROL , LOCOMOTION , PHOTORECEPTORS , PHASE , PHASE STUDIES , SYNTHESIS , RATS , OUTPUT , CONTROL , FUNCTIONS


Subject Categories : Biochemistry
      Anatomy and Physiology


Distribution Statement : APPROVED FOR PUBLIC RELEASE