Some Effects of Postnatal Zinc Deficiency on Developing Rat Brain

Abstract

Extractpups suckled by zinc-adequate, pair-fed, or ad libitum-fed dams. The 12-day-old zincdeficient pups also displayed a A deficiency of dietary zinc during the suckling period of decreased incorporation of thymidine into D~~ and of the rat results in a depression in normal growth, which is, in inorganic sulfate into the acid-insoluble fraction of brain (19). part, due to the inanition experienced by the dam. The pups The studies reported in this paper are an extension of the from such zinc-deficient dams have smaller forebrains at all of above studies on effects of a deficiency of dietary zinc on the time intervals investigated in comparison with pups from brain composition and development during the suckling both zinc-adequate controls. The cell number of the forebrain period. of the zinc-deficient pup was also reduced in comparison with the zinc-adequate pups. RNA concentration did not appear to be affected, although the total RNA content was reduced METHODSbecause the smaller brain size. The protein per Pregnant Sprague-Dawley rats were fed an adequate ration cell was reduced at 6 and 15 days in the zinc-deficient ad libitum until delivery. soon as possible after parturition, forebrain and polysomal profiles displayed abnormal distribu-the dams were moved to clean Plexiglas cages. The number of tion of material between monosomes and polysomes in the in each litter was made equivalent at 8 and only litters zinc-deficient brain. Zinc deficiency during the suckling period that were maintained at or 8 pups during the test period thus appears to disadvantage the animal in terms of body, were used for analysis.animals were then fed a brain growth, accretion of cells into the forebrain, and normal biotin-enriched, 20% sprayed egg white diet (13) which was protein metabolism.modified to incorporate inositol at 1 g/kg and to omit the antibiotic. The zinc content was less than 1 mg/kg by analysis. Speculation One group of dams was given the diet ad libitum and distilled, zinc is essential for development of the brain. infants who deionized water to drink. Two zinc-adequate controls were experience zinc deficiency during the critical period for brain utilized. The first was pair-fed on an individual basis with the growth will suffer brain damage which may be poorly dams in the zinc-deficient group. The second control was fed reversible.the diet ad libitum. Both zinc-adequate controls received zinc at 100 mg/liter in their drinking water. At intervals, the entire litter of a dam was killed by Zinc has been known to be an essential trace element for decapitation. The brains were rapidly removed, separated by more than a century (17), although its essentiality for a blunt dissection into cerebellum and forebrain (the brain mammalian species was not established until 1934 (28), when anterior to the cerebellum excluding the brain stem and the deficiency syndrome was produced in rats. The manifesta-olfactory bulbs), and placed in ice-cold, buffered sucrose. tions of zinc deficiency have been reviewed by Underwood After wei...

Zinc is essential for brain development and function

“…However fetal growth and the number of brain cells were decreased [57]. Early postnatal zinc deficiency impaired synthesis of DNA [58], decreased brain polysomes [59] and impaired synthesis of proteins [60]. After birth zinc deprivation until weaning at 21 days decreased growth and the multiplication and migration of cerebellar external granular cells [61,62].…”

Zinc Deficiency

“…Examples include thymidine kinase,18 DNA-dependent RNA polymerase,16 and aminoacyl-tRNA synthetase.19 Other studies found fewer polysomes on sucrose-density gradients of brain and liver from zinc-deficient rats than control rats. 20,21 More recently the binding of zinc to strategically located cysteines and histidines in the peptide chain of auxiliary transcription factors was reported. Factor of Xenopus laevis was the first of those "finger proteins" to be recog-Sixteen-year-old zinc-deficient Egyptian boy with a prepubertà!…”