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Effect of pyridoxine deficiency on the exploratory behavior of rats
International Journal of Psychophysiology 2 (.,984) 39-43 E~vier
39
PSP 00043
EFFECT OF PYRIDOXINE DEFICIENCY ON THE EXPLORATORY BEHAVIOR OF RATS
A.P.
KRISHNA and T. RAMAKRISHNA *
Department of Life Sciences, University of Calicut, Kerala (India) (Acccptcd Apri~ !4th, ~o....
x J o ~Y!
Key words: exploratory score - pyridoxine - neuromotor coordin:-~.tion- eye opening - maturation - vitamin deficiency
Malnutrition early in life impairs the development of brain as well as behavior. In the present study the behavioral effects of preweaning pyridoxine de.~iciencyin rat~, as reflected by their exploratory score, have been investigated. Tne results clearly indicated that the body weight of pyridoxine-deficient rats was significantly less when compared to the contrgl rats. Besides this, the sign of maturation of sensory perceptual mechanisms like the first day of eye opening and signs of maturatiov, of neuromotor coordination like the day of supported standing are delayed in vitamin-deficient rats. The open-field activity reflected by the exploratory score was observed to be significantly less in vitamin-deficient rats. In short, considerable effects of prenatal pyridoxine deficiency were observed in the neonatal pups as stunting of growth and in the delayed onset of neuromotor coordination as well as a low level of open-f~¢ld activity. The importance of maternal pyridoxine supplementation during pregnancy has been emphasized.
INTRODUCTION
MATERIALS AND METHODS
During the past two decades evidence has accumulated from a n u m b e r of sc~urces suggesting that malnutrition early in life impairs the development of brain as well as behavior (Winick, 1976). Studies o n the consequences of the deficiency of a particular nutrient on the structural and functional m a t u r a t i o n of the brain have been started. Attempts to study the adverse effects of pyridoxine deficiency in adult animals have been m a d e b y b o t h behavioral a n d electrophysiological investigations (Stewart et al., 1975). I n the present study the behavioral effects of pyridoxine de/ici~i~c2;~ from the preweaning stage until 95 days of age in rats, as reflected b y exploratory tendency, is reported.
Animals Albino rats of the Wistar strain were chosen for the study. They were reared in a r o o m with 12 h light and 12 h darkness. A total of 64 male rats was used for this study.
* To whom correspondence should be addressed. 0167-8760/84/$03.00 © 1984 Elsevier Science Publishers B.V.
Food F o o d was prepared from Bengal gram flour with vitamin a n d mineral supplements (Ford, 1977), and was available ad libitum along with water. Rats were divided into two groups, the first group being the control animals and the second experimental group being the pyridoxine-deficient animals. Control animals were obtained by feeding the m o t h e r with n o r m a l food containing all the vitamins in the required quantity. Pyridoxine-deficient animals were obtained by feeding the mother with the food deprived of pyddoxine. Thus pre-
40 natal deficiency o f p y r i d o ~ n e was produced in one group of animals. Body weight o f rats from the two groups in all developing stages was taken and recorded. T w e n t y male rats taken from 3 litters from the control group and twenty male rats taken from 3 litters from the pyridoxine-deficient group were chosen. Pilysicai development and n e u r o m o t o r coordination were assessed to determine the gross maturation o f the animals. Opening of eyes was taken as a criterion for physical development and the day o n which the pups stood erect (with support) was taken as a criterion for assessing n e u r o m o t o r coordination. The day on which the onset of opening of eyes takes place and ihe day on which completion of eye opening occurs were noted for both the groups. The onset of eye opening occurs when there is a slit-like opening of the iris exposing only a portion of the eye ball. This process is complete when the whole of the eye bali is exposed and it usually takes a day for this process to be completed. The day on which the pups first stood with support was also noted for both ~he groups. For these observations, 8 male rats from the control group and 8 from the pyridoxine-deficient group were used. T o assess the behavioral manifestation of impaired development, if any, of brain, exploratory behavior of rats was t a k e n as a parameter. The open-field behavior o ~ rats was observed in a standard box 100 × 100 × 40 cm. The box was covered at the top with a wire net lid. The floor of the box was divided into 25 equal squares and they were n u m b e r e d from 1 to 25. The rat was place:] in a corner of the box and its behavior was observed for 5 rain. Whenever the animal entered a square, a mark was given. After 5 rain exploration the rat was returned to its home cage. T h e score of each rat for 5 rain was taken as an index of its exploratory behavior. The experiment was repeated at the same hour of the day on 5 consecutive days. In other words, no rat was used from either group for more than 6 days for this experiment. Exploratory behavior of control and pyridofine-deficient rats from 3 age groups, 16-21 days, 30-35 days, and 90-95 days, was studied. Three different sets of rats belonging to the control group
and 3 different sets belonging to the pyridoxinedeficient rats were used. Each set comprised of 6 animals. The differences in body weight, delay in eye opening and supported standing, and the difference in the exploratory score between the control rats and the pyfidoxine-deficient rats were subjected to statistical analysis. F o r this purpose Student's t-test was employed.
RESULTS .Rats' weight increased as a function of age. Pyridoxine deficiency brought about a general retardation in the growth of rats. The b o d y weight at different ages - - Days 0, 4, 8, 12, 16, 20, 30 and 40 for control and pyridoxine-deficient rats is graphically represented in Fig. 1. The b o d y weight of the experimental rats at all the ages studied was significantly lower when c o m p a r e d to that of control rats ( P < 0.01). It can be pointed out that the difference in the b o d y weight of control and experinaental rats increased with age as seen b y the widening of the gap b e t w e e n the two curves in Fig. 1. The day of eye opening and the day of supported standing for the control and the experimental group is given in Table I. When we consider
6O q~
c~ 5o
.c 40 {,3O OJ
[20
g
m 10
S
.~/
I 1'6 o' Age in Days
Fig. 1. Growth profile of control and pyridoxine-deficient rats. --, Control rats; . . . . . . , pyridoxine-deficient rats. Sample size n = 20, P < 0.01. The vertical bars denote standard deviation.
4! TABLE I Physical maturation in rats n
=
Sample size 8.
Criteria
Control rats
Day on which onset of eye opening starts Day on which eye opening is complete Day on which supported standing is first observed
PyFidoxinedeficient rats
13.125_4-0.64 16.25_+ 0.707
14.125+0.64
Significance
P < 0.01
17.0 _+0.755 P < 0.01
11.875 _+0.64 16.0 _+0.755
P < 0.001
the day on which the eye opening process begins and the day on which eye opening is completed, it shows a statistically significazt delay in the case of pyridoxine-deficient rats ( P < 0.01). The control rats start the eye opening process at an average age of 13.125 days and the complete eye opening process occurs at the mean age of 14.125 days, whereas the beginning of eye opening in the case of pyridoxine-deficient rats occurs at the mean age
100
a
.!
40
• 0
~oo
~---'I 16 17
. . . . ~. . . . , / !8 19 20
, 21
.9. ° 60 ~
o
20
L~
0 100 BO/
60~ 40
t
t--" 30
. 31
32
.
. 33
.
34 c .:.._-.-~}--~'~-¥~--}~-
35 J
• -I ....~}.... }" .... t t ..... t---
20
9b ~h 42 ~3 ~4 ~ S Age in Days
Fig. 2. Explorato~ score for control and pyddcxine-deficient rats. .......... , Control rats; . . . . . . , pyridoxine-deficientrats. Sample size n = 6, P < 0.01. The vertical bars denote standard deviation.
of 16.25 days and the process ends at the age of 17 days. The onset of supported standing in the pyridoxine-deficient rats was significantly later than that of the control group. There was about 4 days delay in the onset of supported standing in the rats depr,~ved of pyridox~ne in ce~parison with the control group. The exploratory scores for control rats and py~idoxine-deficient rats aged 16-21 days, 30-35 days and 90-95 days are shown in Fig. 2. The exploratory score for pyridoxine-deficient rats of all the 3 age groups was significantly low when compared with the control groups (P < 0.01). The difference in the exploratory score of the pyridoxine-deficient and control groups is most promin,:~nt in the 16-21 day group.
DISCUSSION ??he results clearly showed that the gain in body weight in pyridoxine-deficient rats was considerably low when compared to that of control rats. Th~s low body weight in vitamin-deprived rats may be related to a .certain extent to the maternal fat stores. A reduction in body fat deposits was observed in pyridoxine deficiency (McHenry and Gavin, 1938). So it was apparent that the mother rece£ving pyridoxine-deprived food during pregnancy had low fat stores and that may have contributed to their inability to nurse their young. (Sabo et al., 1971). Besides, the ability of the pups to suckle was probably impaired affecting their postnatal nutrition (A!ton-Mackey and Walker, 1973). As shown by Alton-Mackey and Walker (1973) pups of pyridoxine-deprived mothers gained weight more slowly than normal pups even when fed by non-deprived foster mothers. The delay in the openinz of eyes probably indicates an overe!.l delay in the maturation of sensory perceptual mechanisms in pyridoxine-deprived rats which is corroborated by the studies of Ramakrishna and Mukkadan (1980). The sign of the development of neuromotor coordination, namely the supported standing, is also found to appear late in pyridoxine-deprived
rats. This suggests that under pyridoxine deficiency, the neuromotor coordination is poor and also its maturation is slower than in controls. In 1964, Simonson and his co-workers found that even under protein restriction during prenatal and postnatal periods, there was a delay in the onset of similar neuromotor skills. Exploratory score may be taken as an indicator of open-field activity of the rat. When -we looked at the exploratory scores of control and pyridoxine-deprived rats for all 3 age groups, we found a low score for the pyridoxine-deprived rats. This low degree of exploratory behavior observed in vitamin-deprived rats is statistically significant. The low exploratory score for the pyridoxine-deprived rats aged 16-21 days may be due, to a certain extent, to the delay in maturation of neuromotor coordination. But the low degree of exploration obse~ved in the other age groups, i.e. 30-35 days and 90-95 days, suggests that pyridoxine deficiency has a direct effect in the lowering of the open-field activity of rats. The exploratory activity was found to in~rease during the 6 successive sessions. This type of increase in exploratory score f~'om session to session was marked in the 16-21 day group. In the case of rats belonging to older age groups (30-35 days and 90-95 days) the tendency was more towards levelling off rather than an increase in the score pattern. The underlying cause for the increase :,n the exploratory score in the 16-21 day group may be the rapid maturation processes taking place in the rats' sensory perceptual mechanisms during this period. The concomitant fixation of neuromotor coordination also takes place during this period as was seen in the present experiment. Considerable effects of prenatal pyridoxine deficient), were observed in the neonatal pups as a stuntir/, of growth and in a delayed onset of neuro: ~ o r coordination. This in turn manifests behav~ . ' terms of ~ low degree of open-field activit> ,~,!~:hc~agh pyridoxine is involved in numerous pathways primarily involving amino acids, its role in the synthesis of several putative neurotransmitters is perhaps more important in as far as behavioral regulation is concerned (Stewart et al., 1975). The decrease in the production of GABA (y-aminobutydc acid) in the brains of
pyridoxine-deficient animals has been recognized. The neurotransmitters serotonin and norepinephrir.e also have an important role with respect to behavior. However, the concentrations of serotonin and norepinephrine are not appreciably altered in adult pyridoxine-deficient animals (Sourkes et al., 1960). Stewart et al. (1975) suggest that the turnover ratio rather than the concentration of the neurotransmitters in the brain is considered more important in behavioral regulation, but this aspect in relation to pyridoxine deficiency has not been fully"investigated. Neonatal period and the pre-weaning period are the critical periods for the developing brain. The structural development of brain in terms of cell proliferation is almost complete by 17 days in the rat. Thu~, lhe effect of post-weaning pyridoxine deficiency on the central nervous system (CNS) may be expected to be less severe tba~ preweaning deficiency. The impairment in the structural and functional development of brain caused by preweaning deficiency of pyridoxine may have lasting effects. The adverse effect brought about by the deficiency of pyridoxine on the development of the CNS emphasizes the importance of pyi~idoxine as a nutritional factor during development. Anovulatory steroids are known to increase the requirement of vitamin B6 (Rose, 1966). Many women use these drugs as an oral contraceptive for a prolonged period of time prior to becoming pregnant. A number of workers have established that a significant percentage of pregnant women have a relative pyridoxine-deficiency (Wachstein, 1964). Even a moderate deficiency during the development of the central ne~,ous system may have irreversible adverse effects. Studies are currently underway to investigate the structural and electrophysiological abnormalities bro~ght about r~y the deficiency of pyridoxine in a vital area of '~ " ,+ ~ir~.~,, i.e. the hippocampus.
ACKNOWLEDGEMENTS The first author is grateful to the Council of Scientific and Industrial Research, India for awarding him a research fellowship.
43 REFERENCES Alton-Mackey, M.G. and Walker, B.L. (1973) Graded levels of pyridoxine in the rat diet during gestation and the physical azd ,qeuromotor development of offspr;ng. Amer. J. clin. Nutr., 26: 420-428. Ford, D. (1977) Diets (natural and synthetic): rats and mice. In M. Recheigl, Jr. (Ed.), CRC Handbook Series in Nutritior~ and Food. Section G: Diets, Culture Media, Food Supplements, Vol. I. Diets for Mammals. CRC Press Inc., Cleveland, OH, pp. 107-!32. McHenry, E.W. and Gavin, G. (1928) The B vitamins and fat metabolism I. Effects of thiamine, riboflavin and rice polish concentrate upon body fat. J. biol. Chem., 125: 653. Ramakrishna, T. and Mukkadan, J.K. (1980) Maturation of sensory perceptual mechanism (visual) in rats. A behavioral study. Prcc. Vth All India Symposium on Comparative animal physiology (Abstract) p. 144. Rose, D.P. (1966) The influence of estrogen on tryptophan metabolism in man. Clin. Sci., 31: 265.
Sabo, D.J., Francesconi, R.P. and Gershoff, S.N. (1971) Effect of vitamin B6 deficiency on tissue dehydrogenase and fat synthesis in rat. Jr. Nutr., 10I: 29. Simonson, M., Sherwin, R.W., Anilone, J.K., Yt:, W.Y. and Chow, B.F. (1964) Neuromotor development in progeny of underfed mother rats. J. Nutr., 98: 18. Sourkes, T.L., Murphy, G.F. and Weodward, Jr., V.R. (1960) Effects of deficiencies of pyridoxine, riboflavin and thiamine upon catecholamine content of rat tissues. J. Nutr., 72: 145-152. Stewart, C.N., Coui-~in, D.B. and Bhagavan, H.N. (1975) Avoidance behavior in vitamin B6 deficient rats. J. Nutr., 105: 1363-1380. Wachstein, M. (1964) Evidence for a relative vitamin B6 deficieny in pregnancy and some diseased states. Vitamins Hormones, 22: 705. Winick, M. (1976) Malnutrition and Brain Deveiopment, Oxford University Press, London.
39
PSP 00043
EFFECT OF PYRIDOXINE DEFICIENCY ON THE EXPLORATORY BEHAVIOR OF RATS
A.P.
KRISHNA and T. RAMAKRISHNA *
Department of Life Sciences, University of Calicut, Kerala (India) (Acccptcd Apri~ !4th, ~o....
x J o ~Y!
Key words: exploratory score - pyridoxine - neuromotor coordin:-~.tion- eye opening - maturation - vitamin deficiency
Malnutrition early in life impairs the development of brain as well as behavior. In the present study the behavioral effects of preweaning pyridoxine de.~iciencyin rat~, as reflected by their exploratory score, have been investigated. Tne results clearly indicated that the body weight of pyridoxine-deficient rats was significantly less when compared to the contrgl rats. Besides this, the sign of maturation of sensory perceptual mechanisms like the first day of eye opening and signs of maturatiov, of neuromotor coordination like the day of supported standing are delayed in vitamin-deficient rats. The open-field activity reflected by the exploratory score was observed to be significantly less in vitamin-deficient rats. In short, considerable effects of prenatal pyridoxine deficiency were observed in the neonatal pups as stunting of growth and in the delayed onset of neuromotor coordination as well as a low level of open-f~¢ld activity. The importance of maternal pyridoxine supplementation during pregnancy has been emphasized.
INTRODUCTION
MATERIALS AND METHODS
During the past two decades evidence has accumulated from a n u m b e r of sc~urces suggesting that malnutrition early in life impairs the development of brain as well as behavior (Winick, 1976). Studies o n the consequences of the deficiency of a particular nutrient on the structural and functional m a t u r a t i o n of the brain have been started. Attempts to study the adverse effects of pyridoxine deficiency in adult animals have been m a d e b y b o t h behavioral a n d electrophysiological investigations (Stewart et al., 1975). I n the present study the behavioral effects of pyridoxine de/ici~i~c2;~ from the preweaning stage until 95 days of age in rats, as reflected b y exploratory tendency, is reported.
Animals Albino rats of the Wistar strain were chosen for the study. They were reared in a r o o m with 12 h light and 12 h darkness. A total of 64 male rats was used for this study.
* To whom correspondence should be addressed. 0167-8760/84/$03.00 © 1984 Elsevier Science Publishers B.V.
Food F o o d was prepared from Bengal gram flour with vitamin a n d mineral supplements (Ford, 1977), and was available ad libitum along with water. Rats were divided into two groups, the first group being the control animals and the second experimental group being the pyridoxine-deficient animals. Control animals were obtained by feeding the m o t h e r with n o r m a l food containing all the vitamins in the required quantity. Pyridoxine-deficient animals were obtained by feeding the mother with the food deprived of pyddoxine. Thus pre-
40 natal deficiency o f p y r i d o ~ n e was produced in one group of animals. Body weight o f rats from the two groups in all developing stages was taken and recorded. T w e n t y male rats taken from 3 litters from the control group and twenty male rats taken from 3 litters from the pyridoxine-deficient group were chosen. Pilysicai development and n e u r o m o t o r coordination were assessed to determine the gross maturation o f the animals. Opening of eyes was taken as a criterion for physical development and the day o n which the pups stood erect (with support) was taken as a criterion for assessing n e u r o m o t o r coordination. The day on which the onset of opening of eyes takes place and ihe day on which completion of eye opening occurs were noted for both the groups. The onset of eye opening occurs when there is a slit-like opening of the iris exposing only a portion of the eye ball. This process is complete when the whole of the eye bali is exposed and it usually takes a day for this process to be completed. The day on which the pups first stood with support was also noted for both ~he groups. For these observations, 8 male rats from the control group and 8 from the pyridoxine-deficient group were used. T o assess the behavioral manifestation of impaired development, if any, of brain, exploratory behavior of rats was t a k e n as a parameter. The open-field behavior o ~ rats was observed in a standard box 100 × 100 × 40 cm. The box was covered at the top with a wire net lid. The floor of the box was divided into 25 equal squares and they were n u m b e r e d from 1 to 25. The rat was place:] in a corner of the box and its behavior was observed for 5 rain. Whenever the animal entered a square, a mark was given. After 5 rain exploration the rat was returned to its home cage. T h e score of each rat for 5 rain was taken as an index of its exploratory behavior. The experiment was repeated at the same hour of the day on 5 consecutive days. In other words, no rat was used from either group for more than 6 days for this experiment. Exploratory behavior of control and pyridofine-deficient rats from 3 age groups, 16-21 days, 30-35 days, and 90-95 days, was studied. Three different sets of rats belonging to the control group
and 3 different sets belonging to the pyridoxinedeficient rats were used. Each set comprised of 6 animals. The differences in body weight, delay in eye opening and supported standing, and the difference in the exploratory score between the control rats and the pyfidoxine-deficient rats were subjected to statistical analysis. F o r this purpose Student's t-test was employed.
RESULTS .Rats' weight increased as a function of age. Pyridoxine deficiency brought about a general retardation in the growth of rats. The b o d y weight at different ages - - Days 0, 4, 8, 12, 16, 20, 30 and 40 for control and pyridoxine-deficient rats is graphically represented in Fig. 1. The b o d y weight of the experimental rats at all the ages studied was significantly lower when c o m p a r e d to that of control rats ( P < 0.01). It can be pointed out that the difference in the b o d y weight of control and experinaental rats increased with age as seen b y the widening of the gap b e t w e e n the two curves in Fig. 1. The day of eye opening and the day of supported standing for the control and the experimental group is given in Table I. When we consider
6O q~
c~ 5o
.c 40 {,3O OJ
[20
g
m 10
S
.~/
I 1'6 o' Age in Days
Fig. 1. Growth profile of control and pyridoxine-deficient rats. --, Control rats; . . . . . . , pyridoxine-deficient rats. Sample size n = 20, P < 0.01. The vertical bars denote standard deviation.
4! TABLE I Physical maturation in rats n
=
Sample size 8.
Criteria
Control rats
Day on which onset of eye opening starts Day on which eye opening is complete Day on which supported standing is first observed
PyFidoxinedeficient rats
13.125_4-0.64 16.25_+ 0.707
14.125+0.64
Significance
P < 0.01
17.0 _+0.755 P < 0.01
11.875 _+0.64 16.0 _+0.755
P < 0.001
the day on which the eye opening process begins and the day on which eye opening is completed, it shows a statistically significazt delay in the case of pyridoxine-deficient rats ( P < 0.01). The control rats start the eye opening process at an average age of 13.125 days and the complete eye opening process occurs at the mean age of 14.125 days, whereas the beginning of eye opening in the case of pyridoxine-deficient rats occurs at the mean age
100
a
.!
40
• 0
~oo
~---'I 16 17
. . . . ~. . . . , / !8 19 20
, 21
.9. ° 60 ~
o
20
L~
0 100 BO/
60~ 40
t
t--" 30
. 31
32
.
. 33
.
34 c .:.._-.-~}--~'~-¥~--}~-
35 J
• -I ....~}.... }" .... t t ..... t---
20
9b ~h 42 ~3 ~4 ~ S Age in Days
Fig. 2. Explorato~ score for control and pyddcxine-deficient rats. .......... , Control rats; . . . . . . , pyridoxine-deficientrats. Sample size n = 6, P < 0.01. The vertical bars denote standard deviation.
of 16.25 days and the process ends at the age of 17 days. The onset of supported standing in the pyridoxine-deficient rats was significantly later than that of the control group. There was about 4 days delay in the onset of supported standing in the rats depr,~ved of pyridox~ne in ce~parison with the control group. The exploratory scores for control rats and py~idoxine-deficient rats aged 16-21 days, 30-35 days and 90-95 days are shown in Fig. 2. The exploratory score for pyridoxine-deficient rats of all the 3 age groups was significantly low when compared with the control groups (P < 0.01). The difference in the exploratory score of the pyridoxine-deficient and control groups is most promin,:~nt in the 16-21 day group.
DISCUSSION ??he results clearly showed that the gain in body weight in pyridoxine-deficient rats was considerably low when compared to that of control rats. Th~s low body weight in vitamin-deprived rats may be related to a .certain extent to the maternal fat stores. A reduction in body fat deposits was observed in pyridoxine deficiency (McHenry and Gavin, 1938). So it was apparent that the mother rece£ving pyridoxine-deprived food during pregnancy had low fat stores and that may have contributed to their inability to nurse their young. (Sabo et al., 1971). Besides, the ability of the pups to suckle was probably impaired affecting their postnatal nutrition (A!ton-Mackey and Walker, 1973). As shown by Alton-Mackey and Walker (1973) pups of pyridoxine-deprived mothers gained weight more slowly than normal pups even when fed by non-deprived foster mothers. The delay in the openinz of eyes probably indicates an overe!.l delay in the maturation of sensory perceptual mechanisms in pyridoxine-deprived rats which is corroborated by the studies of Ramakrishna and Mukkadan (1980). The sign of the development of neuromotor coordination, namely the supported standing, is also found to appear late in pyridoxine-deprived
rats. This suggests that under pyridoxine deficiency, the neuromotor coordination is poor and also its maturation is slower than in controls. In 1964, Simonson and his co-workers found that even under protein restriction during prenatal and postnatal periods, there was a delay in the onset of similar neuromotor skills. Exploratory score may be taken as an indicator of open-field activity of the rat. When -we looked at the exploratory scores of control and pyridoxine-deprived rats for all 3 age groups, we found a low score for the pyridoxine-deprived rats. This low degree of exploratory behavior observed in vitamin-deprived rats is statistically significant. The low exploratory score for the pyridoxine-deprived rats aged 16-21 days may be due, to a certain extent, to the delay in maturation of neuromotor coordination. But the low degree of exploration obse~ved in the other age groups, i.e. 30-35 days and 90-95 days, suggests that pyridoxine deficiency has a direct effect in the lowering of the open-field activity of rats. The exploratory activity was found to in~rease during the 6 successive sessions. This type of increase in exploratory score f~'om session to session was marked in the 16-21 day group. In the case of rats belonging to older age groups (30-35 days and 90-95 days) the tendency was more towards levelling off rather than an increase in the score pattern. The underlying cause for the increase :,n the exploratory score in the 16-21 day group may be the rapid maturation processes taking place in the rats' sensory perceptual mechanisms during this period. The concomitant fixation of neuromotor coordination also takes place during this period as was seen in the present experiment. Considerable effects of prenatal pyridoxine deficient), were observed in the neonatal pups as a stuntir/, of growth and in a delayed onset of neuro: ~ o r coordination. This in turn manifests behav~ . ' terms of ~ low degree of open-field activit> ,~,!~:hc~agh pyridoxine is involved in numerous pathways primarily involving amino acids, its role in the synthesis of several putative neurotransmitters is perhaps more important in as far as behavioral regulation is concerned (Stewart et al., 1975). The decrease in the production of GABA (y-aminobutydc acid) in the brains of
pyridoxine-deficient animals has been recognized. The neurotransmitters serotonin and norepinephrir.e also have an important role with respect to behavior. However, the concentrations of serotonin and norepinephrine are not appreciably altered in adult pyridoxine-deficient animals (Sourkes et al., 1960). Stewart et al. (1975) suggest that the turnover ratio rather than the concentration of the neurotransmitters in the brain is considered more important in behavioral regulation, but this aspect in relation to pyridoxine deficiency has not been fully"investigated. Neonatal period and the pre-weaning period are the critical periods for the developing brain. The structural development of brain in terms of cell proliferation is almost complete by 17 days in the rat. Thu~, lhe effect of post-weaning pyridoxine deficiency on the central nervous system (CNS) may be expected to be less severe tba~ preweaning deficiency. The impairment in the structural and functional development of brain caused by preweaning deficiency of pyridoxine may have lasting effects. The adverse effect brought about by the deficiency of pyridoxine on the development of the CNS emphasizes the importance of pyi~idoxine as a nutritional factor during development. Anovulatory steroids are known to increase the requirement of vitamin B6 (Rose, 1966). Many women use these drugs as an oral contraceptive for a prolonged period of time prior to becoming pregnant. A number of workers have established that a significant percentage of pregnant women have a relative pyridoxine-deficiency (Wachstein, 1964). Even a moderate deficiency during the development of the central ne~,ous system may have irreversible adverse effects. Studies are currently underway to investigate the structural and electrophysiological abnormalities bro~ght about r~y the deficiency of pyridoxine in a vital area of '~ " ,+ ~ir~.~,, i.e. the hippocampus.
ACKNOWLEDGEMENTS The first author is grateful to the Council of Scientific and Industrial Research, India for awarding him a research fellowship.
43 REFERENCES Alton-Mackey, M.G. and Walker, B.L. (1973) Graded levels of pyridoxine in the rat diet during gestation and the physical azd ,qeuromotor development of offspr;ng. Amer. J. clin. Nutr., 26: 420-428. Ford, D. (1977) Diets (natural and synthetic): rats and mice. In M. Recheigl, Jr. (Ed.), CRC Handbook Series in Nutritior~ and Food. Section G: Diets, Culture Media, Food Supplements, Vol. I. Diets for Mammals. CRC Press Inc., Cleveland, OH, pp. 107-!32. McHenry, E.W. and Gavin, G. (1928) The B vitamins and fat metabolism I. Effects of thiamine, riboflavin and rice polish concentrate upon body fat. J. biol. Chem., 125: 653. Ramakrishna, T. and Mukkadan, J.K. (1980) Maturation of sensory perceptual mechanism (visual) in rats. A behavioral study. Prcc. Vth All India Symposium on Comparative animal physiology (Abstract) p. 144. Rose, D.P. (1966) The influence of estrogen on tryptophan metabolism in man. Clin. Sci., 31: 265.
Sabo, D.J., Francesconi, R.P. and Gershoff, S.N. (1971) Effect of vitamin B6 deficiency on tissue dehydrogenase and fat synthesis in rat. Jr. Nutr., 10I: 29. Simonson, M., Sherwin, R.W., Anilone, J.K., Yt:, W.Y. and Chow, B.F. (1964) Neuromotor development in progeny of underfed mother rats. J. Nutr., 98: 18. Sourkes, T.L., Murphy, G.F. and Weodward, Jr., V.R. (1960) Effects of deficiencies of pyridoxine, riboflavin and thiamine upon catecholamine content of rat tissues. J. Nutr., 72: 145-152. Stewart, C.N., Coui-~in, D.B. and Bhagavan, H.N. (1975) Avoidance behavior in vitamin B6 deficient rats. J. Nutr., 105: 1363-1380. Wachstein, M. (1964) Evidence for a relative vitamin B6 deficieny in pregnancy and some diseased states. Vitamins Hormones, 22: 705. Winick, M. (1976) Malnutrition and Brain Deveiopment, Oxford University Press, London.