Pineal response after pyridoxine test in children

Abstract

To characterize the pineal response to pyridoxine, plasma melatonin was measured in one hundred and twenty children 3 hours after vitamin B6 administration. The children, aged between 1.5 and 8 years, were divided in four groups as follows: a) control day group, grouping 27 children sampled at 9:00 and at 12:00; b) control night group, grouping 29 children sampled at 21:00 and at 24:00; c) pyridoxine day group, grouping 30 children sampled at 9:00, then intravenously (i.v.) injected with 3 mg/kg of pyridoxine, and sampled at 12:00; and d) pyridoxine night group, grouping 34 children sampled at 21:00, i.v. injected with 3 mg/kg of pyridoxine, and sampled at 24:00. Melatonin concentration was measured by radioimmuno assay. The data obtained showed a significant increase in melatonin levels after pyridoxine administration in the pyridoxine night group (39.87 +/- 8.02 pg/ml basal vs 88.45 +/- 9.21 pg/ml after pyridoxine, p < 0.001). The other groups did not showed significant differences in melatonin concentrations. Statistical analysis shows that the administration of pyridoxine during the nocturnal hours represents a stimulating factor to increase the pineal production of melatonin in children.

The neuroprotective role of melatonin in neurological disorders

“…As folate is essential in the methylation step of converting N‐acetylserotonin to melatonin, folate deficiency decreases melatonin release in rats (Fournier, Ploye, Cottet‐Emard, Brun, & Claustrat, ). Moreover, vitamin B6 (pyridoxine) plays an important role in tryptophan decarboxylation and increases the release of melatonin by the pineal gland in children but not in adults (Munoz‐Hoyos et al, ; Luboshitzky et al, ).…”

Dietary factors and fluctuating levels of melatonin

“…Nocturnal melatonin levels in the blood, however, doubled in over 100 small children between the ages of 18 months and 8 years when pyridoxine was administered at night intravenously at doses of 3 mg/kg (78). Any possible deficiency of pyridoxine in these hospitalized children was not reported.…”

Melatonin as a potential inhibitor of kidney cancer: A survey of the molecular processes

“…11 Vitamin B6 acts as a coenzyme for the decarboxylation of tryptophan and leads to the melatonin synthesis in children at pre-pubertal ages. 12 Some studies have reported that Vitamin B6 does not affect the secretion of melatonin in adults. 13 However, it is observed that injections of vitamin B6 strengthen the biosynthesis of melatonin.…”

“…Some factors affect the synthesis of melatonin including the availability of tryptophan, folate status, and vitamin B6 11 . Vitamin B6 acts as a coenzyme for the decarboxylation of tryptophan and leads to the melatonin synthesis in children at pre‐pubertal ages 12 . Some studies have reported that Vitamin B6 does not affect the secretion of melatonin in adults 13 .…”