Dakshinamurti,K; Paulose,C S; Viswanathan,M; Siow,Y L(Department of Biotechnology, 1988)
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Abstract:
Veuruenducrim lri v j p .rim,
deficienc:v. NEUROSCI BIOBEHAV REV 12(3/4) 189-193. 1988.- Dihydroxyphenylalanine decarboxvlase and
5-hydroxytryptophan decarboxvlase respectively have high and low affinities for pyridoxal phosphate. In the pyridoxinedeficient
animal. hypothalamic serotonin content is significantly reduced without any change in catecholamine levels.
Hypothalamic neurotransmitters affect the hvpothalamo-pituitary-end organ axes. Specifically, the decrease in hypothalamic
serotonin in the pyridoxine-deficient rat results in tertiary hypothyroidism. In addition. pineal function is affected in
deficient animals due to decreased synthesis of melatonin.
Viswanathan,M; Siow,Y L; Paulose,C S; Dakshinamurti,K(Department of Biotechnology, May 24, 1988)
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Abstract:
Pvridoxine deficiency causes physiologically significant decrease in brain serotonin (5-HT) due to decreased decarboxylation of 5-
hvdroxvtrvptophan (5-HTP). We have examined the effect of pyridoxine deficiency on indoleamine metabolism in the pineal gland, a
tissue with high indoleamine turnover. Adult male Sprague-Dawley rats were fed either a pyridoxine-supplemented or pyridoxinedeficient
diet for 8 weeks. Pyridoxine deficiency did not alter the pattern of circadian rhythm of pineal 5-HT. 5-hvdroxvindoleacetic
acid (5-HIAA), V-acetvlserotonin (NAS). and melatonin. However the levels of these compounds were significantly lower in the
pineal glands of pyridoxine-deficient animals. Pineal 5-HTP levels were consistently higher in the pyridoxine-deficient animals and a
conspicuous increase was noticed at 22.00 h. Increase in pineal NAS and melatonin levels caused by isoproterenol (5 mg kg at 17.00 h)
were significantly lower (P < 0.05) in the pyridoxine-deficient animals. Treatment of pyridoxine-deficient rats with pvridoxine restored
the levels of pineal 5-HT, 5-HIAA. NAS. and melatonin to values seen in pyridoxine-supplemented control animals. These results
suggest that 5-HT availability could be an important factor in the regulation of the synthesis of pineal NAS and melatonin.