Effects of damage to the suprachiasmatic area of the anterior hypothalamus on the daily melatonin and cortisol rhythms in the rhesus monkey
The effects of lesions of the suprachiasmatic nucleus (SCN) on the circadian rhythms in melatonin and cortisol were examined in the rhesus monkey. The concentrations of the two hormones were monitored in cerebrospinal fluid (CSF) withdrawn from two sham-operated animals, two animals with complete bilateral SCN lesions, and two animals with partial SCN damage at 4 and 8 months after surgery. In the sham-operated animals, as in the intact animal, the daily melatonin rhythm was entrained to the daily light-dark cycle, was suppressed in constant light, and persisted in constant darkness. In contrast, neither animal with complete SCN ablation exhibited a daily pattern of CSF melatonin in diurnal lighting at 4 months after surgery nor were their melatonin levels at constant low values. Furthermore, CSF melatonin concentrations were not suppressed in either animal by constant light. Surprisingly, at 8 months after surgery, spectral analysis revealed a 24-hr component to the melatonin patterns for each animal with complete SCN ablation in both diurnal lighting and constant darkness. The two animals with partial SCN damage exhibited a daily melatonin rhythm in diurnal lighting, but constant light did not suppress CSF melatonin concentrations consistently. Daily rhythms persisted in both for a 6 1/2-d period of study in constant darkness. In contrast to the alterations in the melatonin rhythm after SCN damage, there was no apparent effect of either partial or complete SCN ablation on the daily CSF cortisol rhythm. These data indicate that, in the rhesus monkey, the SCN is important for the generation, photic entrainment, and photic suppression of the melatonin rhythm. However, circadian oscillators located outside of the SCN region may control the normal daily cortisol rhythm and perhaps the melatonin rhythm in the absence of the SCN.
- Research Organization:
- National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD
- OSTI ID:
- 5132687
- Journal Information:
- J. Neurosci.; (United States), Vol. 1:12
- Country of Publication:
- United States
- Language:
- English
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ABSCESSES
PATHOLOGY
HYDROCORTISONE
DAILY VARIATIONS
MELATONIN
AUTORADIOGRAPHY
BIOCHEMICAL REACTION KINETICS
CEREBROSPINAL FLUID
HYPOTHALAMUS
MACACUS
PHYSIOLOGY
ADRENAL HORMONES
AMINES
ANIMALS
AZOLES
BIOLOGICAL MATERIALS
BODY
BODY FLUIDS
BRAIN
CENTRAL NERVOUS SYSTEM
CORTICOSTEROIDS
GLUCOCORTICOIDS
HETEROCYCLIC COMPOUNDS
HORMONES
HYDROXY COMPOUNDS
INDOLES
KETONES
KINETICS
MAMMALS
MATERIALS
MONKEYS
NERVOUS SYSTEM
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
ORGANS
PATHOLOGICAL CHANGES
PREGNANES
PRIMATES
PYRROLES
REACTION KINETICS
STEROID HORMONES
STEROIDS
TRYPTAMINES
VARIATIONS
VERTEBRATES
550901* - Pathology- Tracer Techniques
550201 - Biochemistry- Tracer Techniques