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Aging and photoperiod regulate glutamic acid decarboxylase(67) messenger RNA expression
1Department of Anatomy and Neurobiology, University of Kentucky Medical Center, 800 Rose Street, Lexington, KY 40536-0298, USA. mjdunc0@pop.uky.edu
Brain Research. Molecular Brain Research
|October 16, 1999
Summary
Short day photoperiods increase GABA-producing enzyme GAD(67) mRNA in the brain
Area of Science:
- Neuroscience
- Chronobiology
- Molecular Biology
Background:
- Aging and short photoperiods alter circadian rhythms and suprachiasmatic nuclei (SCN) function.
- GABAergic signaling modulates SCN neuronal activity.
- Neuropeptide mRNA expression in the SCN is affected by these chronic conditions.
Purpose of the Study:
- Investigate the effects of photoperiod and aging on GAD(67) mRNA expression in the SCN and reticular thalamic nucleus (RTN).
- Determine if GAD(67) mRNA modulation is a common mechanism for circadian rhythm regulation.
Main Methods:
- In situ hybridization was used to detect GAD(67) mRNA.
- Siberian hamsters were exposed to long or short photoperiods.
- Syrian hamsters of different ages (young and old) were studied under long photoperiods.
Main Results:
- Short day photoperiods significantly increased GAD(67) mRNA in the SCN and RTN.
- Aging significantly decreased GAD(67) mRNA in the RTN but not the SCN.
- Photoperiod and aging had differential effects on GAD(67) mRNA expression.
Conclusions:
- SCN GAD(67) mRNA modulation is linked to photoperiodic neuropeptide regulation, not general chronic circadian rhythm control.
- Photoperiod and aging differentially impact GAD(67) mRNA expression in the RTN.