Indian J Physiol Phannacol 1994; 38(2) : 113-116

EFFECT OF PYRIDOXINE DEFICIENCY ON MATURAnONOF NEUROMOTOR COORDINAnONS

A. P. KRISHNA* AND T. RAMAKRISHNAt

Department ofPhysiology and Biochemistry,A.B. Shetty Memorial Institute ofDental Sciences,Mangalore ·575 003

and'Department ofLife Science,University ofCalicut,Calicut· 673 635

( Received on June 9, 1993 )

Abstract: In the present study the effect of preweaning pyridoxine deficiency indicatesthat the body weight and brain weight of pyridoxine deficient rats were significantlylower when compared to the control rats. Onset and stabilisation of reflex reactionswere also delayed in the pyridoxine deficient rats. Maturation of neuromotor coordinationin the vitamin deficient group was significantly slow as compared to the control groups.This suggests that the importance of maternal pyridoxine supplementation cannot beoverlooked in pregnant women especially after prolonged use of anovulatory steroids.

Key words: pyridoxine deficiency neuromotor coordinations

INTRODUCTION

Malnutrition in early life has an adverse effecton the growth of body and the brain. Impaireddevelopment of the brain may lead to abnormalbehaviour (1). Attempt to study the adverse effect ofpyridoxine deficiency in adult animals was made bothfor behavioural and electrophysiological parameters (2).In the present study, the effect of preweaning pyridoxinedeficiency in rats on the physical growth of the bodyand brain and also on the development of reflex reactionsand neuromotor coordinations have been investigated.

METHODS

Albino rats of Wistar strain were reared with 12hlight and 12h darkness. Food was prepared from bengalgram flour with vitamin and mineral supplements (3)and was available ad libitum along with water. Ratswere di~ided into control and experimental groups.Control pups were reared by the mothers fed with'normalfood containing all the minerals and vitamins in requiredquantity. Experimental pups were reared by the mothersfed with food deprived of pyridoxine, resulting in

·Corresponding Author

maternal prenatal pyridoxine deficiency. Mothers werefed with B6 deficient diet during pregnancy and lactation.

Body weight of rats from the two groups wasrecorded. Male rats (n = 20) taken from 3 litters ofcontrol rats and male rats (n =20) taken from 3 littersof B6 deficient groups were chosen. To assess the growthof the brain, the wet weight of the bniin at differentstages of development was recorded. To assess thephysical development of the body, three criteria selectedwere (i) the day of onset of unfolding of external earand its completion, (ii) the day of onset of eruption ofincisors and its completion and (iii) the day of onset ofopening of eyes and its completion. The onset of eyeopening occurs when there is a slit like opening of theeyelids exposing only a portion of the eye ball. Thisprocess is usually complete in a day when the eye isfully exposed.

The criteria to assess the development of reflexreactions and the neuromotor coordinations were (i)the day on which righting reflex starts and is completed,(ii) the day on which crawling starts and (iii) the dayon which supported standing starts.

114 Krishna and Ramakrishna Indian J Physiol Pharmacol 1994; 38(2)

RESULTS

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AGB ill DAYSFig. 2 : Brain weight profile of control (-) and pyridoxine

dcficient (---) rats. The vertical bars denote S.D. P<O.OIbetween the values of particular ages. n = 6 for bom thegroup.

Criteria Day of Control Pyrido:4:ine deficient(n =8) (n =8)

Upholding of Onset 3.3± 1.3 4±1.4

Extemal Ears Completion 4±1.'1 4.7±1.2

Eruption of Onset 11.I±1 " 12.I±O.9*

Incisors Completion 12± 1.4 13.2±1.2*

Opcning Onset 13.1±0.6 16.2±0.7*

of Eyes Complction 14.1±0.6 17.0±0.7*

Values are mean ± S.D. *P<O.OI

TAGLE I: Physical development of rat.

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rats is significantly lower when compared to the controlgroup (Fig. 2.). The unfolding of external ear flaps incontrol and experimental rats starts at an average ageof 3.3±1.3 and 4±1.4 days respectively (Table I) and iscompleted at4±1.4 and 4.7±1.2 days in control and PDrats respectively (Table I). Eruption of incisors begins

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AGE IN DAYS

Fig. I : Growth profile of control (-) and pyridoxine deficient (---)rats. The vertical bars denote S.D. P<O.OI between the valuesof particular ages. n =20 for bam the groups.

On the day of birth and each day thereafLer, allpups from both the groups were tested for rightingreflex (RR) by placing the pup on its back on a hardsurface and measuring the time required La turn overwith all paws flat. Ability to turn over in 2.5s or lesswas recorded as positive RR (4). Crawling was definedas positive if the pup advanced forward, (belly raised)rising on all limbs in coordinated paddling movement.The day on which the pups first stood with support wasalso noted for both the groups. For these observations6 male rats from the control group and 6 male ratsfrom pyridoxine deficient group were used. The valueswere expressed as mean ± S.D. The statistical evaluationof the results were carried out using students '1' test.

The body weight of PD rats at all the ages studiedwas significantly lower when compared to that of controlrats (P<O.OI), and this difference increased with age(Fig. I). Whole brain weight (wet) of vitamin deprived

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Indian J Physiol Pharmacol 1994; 38(2) Pyridoxine Deficiency 115

at an average age of 11.1±1.4 and 12.1±0.9 days andis completed at 12±1.4 and 13.2±1.2 days in controland experimental rats respectively (Table I). The openingof the eyes and its completion is also delayed in PDrats significantly.

As shown in Table II, righting reflex appears at3.3±1.1 days and is perfect at 6.1± 1.6 days in controlrats but in PD rats it is significantly delayed to 4±1.4and 8.6±1.1 days respectively. Similarly crawlingphenomenon and the capacity of supported standingare delayed in PD rats significantly.

TABLE II: Development of renex reactions and neuromotorcoordinations in rat.

Criteria Day of Control Pyridoxine deficient(n =6) (n =6)

Righting Onset 3.3± I.l 4±1.4'ReOex Completion 6.1±1.6 8.6± 1.\'

Crawling Onset 5.5±1.1 6.5±1.2'

StandingSupported Onset 11.6± I.l 16±0.7"

Values are mean ± S.D. 'P < 0.01; up < 0.001

DISCUSSION

The low body weight of PD pups is partly relatedLO the depleted body fat de[X>sits of pyridoxine deficientmothers (5), which may cause in them poor nursingability (6) and poor suckling ability of the PD pups(7). The pups of pyridoxine deficient mothers gainedweight more slowly than normal pups even when fedby non-deprived foster mothers (7). Tt.is suggests thatthe prenatal deprivation of pyridoxine, independentlyaffects the growth.

A spurt in brain weight observed during the criticalperiods of growth namely 10 to 20 days of age isassociated with the neuron growth and multiplication.The neuron multiplication rate in PD animals are farbelow the rate in control rats, and may partly accountfor the delayed maturation of reflex reactions andneuromotor coordinations.

The delay in milestones of physical developmentsuggests the overall retarded physical growth of aniamlsunder pyridoxine deficient conditions. Moreover, the

delay in the opening of eyes probably indicates anoverall delay in the maturation of sensory perceptualmechanism in PD rats. Late appearance of relfexreaction and neuromotor coordinations in PD ratssuggests that under PD, the neuromotor coordinationis poor and slow in maturation. Under protein restrictionduring pre and postnatal periods there was a delay inthe onset of similar skills (8) and exploratory score inopenfield activity was significantly lower in PD rats(9).

Pyridoxine is involved in numercus metabolicpathways including the synthesis of several putativeneurotransmitters, and it is perhaps more important inas far as the maturation of neuromotor coordinationsand behaviour are concerned (2). The decrease in theproduction of GABA (y- aminobutyric acid) in the brainsof pyridoxine deficient animals has been recognised.The turnover ratio, rather than the concentration of theneurotransm itters in the brain is considered moreimportant in behavioural regulation (2), but this aspectin relation to pyridoxine deficiency has not been fullyinvestigated. It is observed that in human infants theimportant milestones of child's development such asholding up the head, dentition, sitting, standing,walking etc. are delayed in a number of deficienciesincluding protein caloric deprivation. The adverse effectbrought about by the pyridoxine deficiency on thedevelopment of CNS emphasises the importance ofpyridoxine as a nutritional factor during pregnancy.Anovulatory steroids are known to increase therequirement of vitamin B6 (10) and women who usecontraceptive pills for prolonged period of time mayhave a relative deficiency of pyridoxine (11). To ensurethe normal development of the child, materna] pyridoxinesupplementation during pregnancy and lactation isrecommended. However, further rehabilitation studiesare necessary to see whether the above mentioned effectsare reversible or not.

ACKNOWLEDGEMENTS

The first author is grateful to Dr. N. SridharShelly, Dean, A.B. Shelly Memorial Institute of DentalSciences, Mangalore and to Sri Vinaya Hegde,Secretary, Nitte Education Trust, Mangalore for theirencouragement and support.

116 Krishna and Ramakrishna Indian J Physiol Pharmacol 1994; 38(2)

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