24-Hour rhythm in gene expression of nitric oxide synthase and heme-peroxidase in anterior pituitary of ethanol-fed rats

• Published in: Neuroscience letters Vol. 425; no. 2; pp. 69 - 72
• Main Authors: Jiménez-Ortega, Vanesa, Cardinali, Daniel P., Poliandri, Ariel H.B., Cano, Pilar, Toso, Carlos F. Reyes, Esquifino, Ana I.
• Format: Journal Article
• Language: English
• Published: Shannon Elsevier Ireland Ltd 25-09-2007; Elsevier
• Subjects: Adenohypophysis; Alcohol-Induced Disorders, Nervous System - enzymology; Alcohol-Induced Disorders, Nervous System - genetics; Alcohol-Induced Disorders, Nervous System - physiopathology; Animals; Biological and medical sciences; Carbon Monoxide - metabolism; Central Nervous System Depressants - adverse effects; Chronobiology; Circadian Rhythm - drug effects; Circadian Rhythm - genetics; Circadian rhythms; Ethanol - adverse effects; Ethanol toxicity; Free Radicals - metabolism; Fundamental and applied biological sciences. Psychology; Gene Expression Regulation, Enzymologic - drug effects; Gene Expression Regulation, Enzymologic - genetics; Gonadotropins, Pituitary - metabolism; Gonadotropins, Pituitary - secretion; Heme oxygenase-1; Heme Oxygenase-1 - genetics; Male; Nitric oxide synthase; Nitric Oxide Synthase - genetics; Nitric Oxide Synthase Type I; Nitric Oxide Synthase Type II - genetics; Nitrites; Nitrites - blood; Oxidation-Reduction; Oxidative Stress - drug effects; Oxidative Stress - genetics; Pituitary Diseases - chemically induced; Pituitary Diseases - enzymology; Pituitary Diseases - genetics; Pituitary Gland, Anterior - drug effects; Pituitary Gland, Anterior - enzymology; Pituitary Gland, Anterior - physiopathology; Rats; Rats, Wistar; RNA, Messenger - drug effects; RNA, Messenger - metabolism; Up-Regulation - drug effects; Up-Regulation - genetics; Vertebrates: anatomy and physiology, studies on body, several organs or systems; Vertebrates: nervous system and sense organs; Circadian rhythms; Adenohypophysis; Ethanol toxicity; Nitric oxide synthase; Nitrites; Heme oxygenase-1; Endocrine gland; Rat; Toxicity; Biological rhythm; Heme; Peroxidase; Ethanol; Enzyme; Rodentia; Heme oxygenase (decyclizing); Circadian rhythm; Gene expression; Nitric-oxide synthase; Feeding; Vertebrata; Mammalia; Peroxidases; Animal; Oxidoreductases
• ISSN: 0304-3940; 1872-7972
• DOI: 10.1016/j.neulet.2007.08.019

Chronic exposure of rats to ethanol results in significant changes in pituitary hormone secretion. However, identification of the site(s) and mechanism of action of ethanol to induce these effects remains elusive. Free radical damage at the adenohypophyseal level may play a role in the decline in serum gonadotropin levels in ethanol-fed rats. Since 24-h changes in redox state occurred, we analyzed the 24-h changes in pituitary gene expression of the prooxidant enzymes nitric oxide synthase (NOS) 1 and 2, and of heme oxygenase-1 (HO-1) enzyme, and in plasma NO
2
− and NO
3
− (NO
x
) levels, in ethanol and control rats. Male rats, 35-day-old, received a liquid diet for 4 weeks. The ethanol-fed group received a similar diet to controls except for that maltose was isocalorically replaced by ethanol. Animals were killed at six time intervals during a 24-h cycle. Anterior pituitary mRNA levels encoding NOS1, NOS2 and HO-1 were measured by real-time PCR analysis. Plasma NO
x
concentration was determined by the Griess reaction. Ethanol feeding of prepubertal rats changed significantly the 24-h pattern of expression of NOS1, NOS2 and HO-1 in the adenohypophysis and augmented NOS2 and HO-1 mRNA levels. Peak values for the three enzymes in ethanol-fed rats occurred at the beginning of the scotophase (i.e., at 21:00
h). Ethanol feeding augmented mean values plasma NO
x
levels with a maximum at 13:00
h while in controls a biphasic pattern was observed, with peaks at 09:00
h and 17:00–21:00
h. One of the mechanisms by which ethanol augments oxidative damage in the adenohypophysis may include overproduction of nitric oxide and carbon monoxide.