In the rat pineal gland, but not in the suprachiasmatic nucleus, the amount of constitutive neuronal nitric oxide synthase is regulated by environmental lighting conditions.
To investigate whether the expression of neuronal isoform of nitric oxide synthase is photoneurally regulated, we examined the amount of the enzyme by means of Western Blot analysis under different environmental lighting conditions in two photoneuronally regulated tissues, the pineal gland and the suprachiasmatic nucleus of the rat. In the pineal gland nitric oxide synthase immunoreactivity was strikingly decreased when rats had been exposed for 8 days to light:dark 20:4 conditions or to constant light. The decline in nitric oxide synthase immunoreactivity following LL reversed after 4 days under light:dark 12:12. We conclude that in the rat pineal the amount of neuronal nitric oxide synthase is controlled by environmental lighting conditions. That it is not justified to extrapolate from the pineal to other photoneuronally regulated centers is illustrated by the present finding that the suprachiasmatic nucleus did not reveal changes in the amount of neuronal nitric oxide synthase.
Spessert
R
R
Department of Anatomy, Johannes Gutenberg University, Mainz, Germany.
Layes
E
E
Schollmayer
A
A
Reuss
S
S
Vollrath
L
L
D000594:Amino Acid Oxidoreductases / Q000302:isolation & purification / Q000378:metabolism* / Q000528:radiation effects; D000818:Animals; D015153:Blotting, Western; D003624:Darkness; D008027:Light; D008029:Lighting; D008297:Male; D009474:Neurons / Q000201:enzymology* / Q000528:radiation effects; D019001:Nitric Oxide Synthase; D009830:Olfactory Bulb / Q000201:enzymology; D009928:Organ Specificity; D010870:Pineal Gland / Q000201:enzymology* / Q000528:radiation effects; D051381:Rats; D017207:Rats, Sprague-Dawley; D013493:Suprachiasmatic Nucleus / Q000201:enzymology* / Q000528:radiation effects
D019001:Nitric Oxide Synthase; D000594:Amino Acid Oxidoreductases