Zw. Fu et al., Regulation of the expression of serotonin N-acetyltransferase gene in Japanese quail (Coturnix japonica): II. Effect of vitamin A deficiency, J PINEAL R, 27(1), 1999, pp. 34-41
Levels of serotonin N-acetyltransferase [arylalkylamine N-acetyltransferase
(AANAT); EC2.3.1.87] mRNA, AANAT activity, and melatonin display a rhythmi
c pattern in both the pineal gland and the retina. It has been shown that v
itamin A is required to maintain the rhythm of melatonin synthesis in the p
ineal gland of Japanese quail. To understand the mechanism underlying the d
irect relationship among these factors, we developed an assay system sensit
ive enough to determine AANAT mRNA, AANAT activity, and melatonin content f
rom a single pineal gland of Japanese quail. Positive direct relationships
were found among these three parameters. We next deprived Japanese quail of
vitamin A by feeding them a vitamin A-free diet supplemented with retinoic
acid, and examined the effects of vitamin A deficiency on the expression o
f AANAT mRNA in the pineal gland and the retina. Vitamin A deficiency reduc
ed both the expression of AANAT mRNA and melatonin content in the pineal gl
and. Retinal AANAT mRNA rhythm disappeared in vitamin A-deficient quails. M
oreover, the responsiveness of the pineal gland and the retina to light was
reduced by vitamin A deficiency when compared with the control group.