The effect of vitamin B6 deficiency on learning and memory in rats and its related mechanisms

【Abstract】 Objective To observe the effect of Vitamin B6 (VB6) deficiency on learning and memory function in rats during the growth period , and to explore the related mechanisms from brain development and neurotransmitters. The method of learning and memory in rats by detecting avoidance method, nucleic acids and brain monoamine neurotransmitter content was determined by fluorescence. Results VB6 lack the learning and memory ability of rats decreased significantly, while dopamine in the brain serotonin and 52 significantly reduced brain development and no abnormal changes of indicators. Conclusion VB6 by adjusting the level of monoamine neurotransmitters in the brain, learning and memory in rats.

【Key words】 Vitamin B6 Learning and memory Brain development Neurotransmitter Vitamin B6

(V B6) mainly participates in various substances and energy metabolism in the body in the form of coenzyme. Found foreign parent V B6 deficiency can cause dysfunction progeny many Enzyme systems, such as glutamic acid decarboxylase (GAD) activity changes and transamination enzymes (GOT, GPT), and these enzymes for the synthesis of neurotransmitters, medullary Sheath formation and Amino Acid metabolism are extremely important. The lack of VB6 in newborn animals can cause abnormal behaviors such as tremors, irritability, and movement disorders. In recent years, it has been found that rats lack VB6, the activity of GAD in the brain is reduced , and seizures are induced at the same time . Human body experiments have also found abnormalities in EEG in patients with VB6 deficiency , accompanied by emotional changes such as emotions . It is speculated that VB6 plays a role in maintaining normal brain function. Important role. Learning and memory is one of the advanced functions of the brain, affecting about VB6 on learning and memory has not been systematically studied. And to explore the mechanisms of neurotransmitters from the brain development and experimental aspects of growing rats fed with the lack of VB6 feed, change the behavior of learning and memory in rats observed, for the future to ensure the normal functioning of learning and memory function from the nutritional point of lay Theoretical basis.

Materials and Methods

I. Grouping and breeding of experimental animals

About 70g Wistar rats (animal room provided by the present) 30, were randomly divided into 3 groups of male and female, with stainless steel cages were housed free access to water. Lack of VB6 feed , lack of VB6 feed ; control group , normal VB6 (7mg/kg) feed ; feed group , control group feed , and lack group feed ( daily food intake and lack group ), feed reference AIN -93 synthetic feed formulation. After 28 days of feeding behavioral experiments, rats were decapitated after a week of brain tissue separation at low temperatures.

Second, observation indicators and determination methods

1. Red blood cell aspartate aminotransferase (AST) activity coefficient : enzyme coupling method

2. Passive avoidance reaction experiment : The dark-avoiding method is designed by using the habit of rat darkness. The experimental device is divided into two chambers of light and dark , each having a size of 20 × 30 × 40 cm, and an arched small door is connected between the chambers. A 15W tungsten lamp is placed above the bright room , and the bottom of both rooms is covered with a stainless steel grid. The bottom of the darkroom is connected to a voltage of 40V . Face facing away from the first experiment rats hole into the light compartment, while the timer is started, the recording time of their entry into the dark, as the incubation period. Immediately after the rats passed through the opening into the darkroom , the rats were energized until the rats were shocked and escaped to the bright room , and the time when the rats were shocked to escape the darkroom was recorded. The first day of learning, memory tests conducted one week later, the rats were observed and recorded into the light chamber and the dark time within 5min error rate (number of animals Error reaction / number of animals in each group).

3. Brain tissue protein content : Coomassie brilliant blue method

4. Brain tissue nucleate content : Fluorescence probe Ethidium Bromide method

5. Brain tissue monoamine neurotransmitter content : fluorescence spectrophotometry

Third, statistical processing

Behavioral experiments represented by the median M, the groups were compared using the rank sum test; other indicators are represented by x ± s, the groups were compared with t test.

result

I. Rat erythrocyte AST activity coefficient Red blood cell AST activity coefficient is related to the body's vitamin B6 level . More than 1.8 can be considered as VB6 deficiency. The lack of erythrocyte AST activity coefficient in this experiment averaged 2101 (2101 ± 0139), which was significantly higher than the other two groups ( 1120 ± 0125 for the feeding group and 1141 ± 0130 for the control group ), indicating that the body was in a state of VB6 deficiency.

Second, the ability of rats to learn and remember

The results show avoidance rats: rats lacking in the training stage incubation period (residence time in the light) is slightly higher than the other two groups, suggesting that its low sensitivity to light stimulation, and into the dark suffered shock time was significantly higher than the other two groups, which showed poor ability to respond to the strain, a long memory time is obtained. After one week, the memory reproduction showed that the rats in the control group stayed in the bright place for 5 minutes, while the rats in the lack group had 60% errors , and the error rate was significantly higher than the other two groups . 3. Brain development status of the brain 3 The group was basically the same , the hippocampus weight deficiency group was slightly lower than the other two groups ; the brain nucleic acid and protein content did not differ significantly in each group. Fourth, the rat brain tissue monoamine neurotransmitter content in the rat brain norepinephrine level 3 There is no significant difference in the group .

However, the dopamine and 52 hydroxytryptamine (52HT) content deficiency group was significantly lower than its

discuss

In this study, the feed shortage caused by the body VB6 VB6 rats lacking. The learning and memory ability of rats was tested by avoiding darkness test . The results showed that VB6 deficiency can significantly reduce the latency and avoidance of electric shock in the passive avoidance experiment of experimental rats , indicating that VB6 deficiency can affect the strain response ability of rats , suggesting that VB6 pairs Rats have an important role in learning and memory. Learning and memory is a complex process . The normal development and structural integrity of the brain is a necessary condition for the normal function of brain function . The synthesis and release of neurotransmitters is one of the physiological basis of learning and memory. But VB6 whether by influencing brain development, mediated neurotransmitter involved in regulating the synthesis of learning and memory has not yet been confirmed. The lack of B6 affects brain development has been reported in recent years. Kirksey et al. fed pregnant mice with VB6- free feed , and observed brain histomorphology on the 15th day of birth , and found structural abnormalities in multiple brain regions : reduced number of neocortical and cerebellar neurons , cerebellar Purkinje cells The dendritic branches of neocortical pyramidal cells and stellate cells are reduced ; the synaptic density of the striatum and cerebral cortex is reduced , and a large number of pyknotic neurons appear , thereby presuming the shortening of neuronal life. Corresponding to its structure , the protein, nucleic acid and lipid synthesis and metabolism of the brain are abnormal. Geng et al. used in vitro neural cell culture in fetal rat brain tissue at 18 days of gestation and found that VB6 promoted the growth of hippocampus and cortical neurons. These studies have shown that V B6 is an essential nutrient for brain development during pregnancy and lactation. However, there are few reports on the effects of VB6 on brain development in rats after weaning. We observed the brain development of VB6- deficient rats after weaning . It was found that the weight of VB6- deficient rat brain and hippocampus and the protein and nucleic acid content in the brain were not significantly different from those in the control group , indicating that VB6 deficiency did not cause rats. Significant abnormalities in brain development. The reason may be body organs, tissue growth are not synchronized, relative to other organs, the brain fast growth rate, a short process. Pregnancy and lactation are the vigorous periods of brain development , and brain development after weaning is basically over , so it is not sensitive to VB6 deficiency , suggesting that VB6 deficiency is unlikely to interfere with the biosynthesis of proteins and nucleic acids by affecting brain development , thereby causing learning and memory impairment. . Monoamine-based transmitter systems are involved in learning and memory processes. Damage to the dopaminergic system will cause impairment of learning and memory functions , such as Parkinson's disease is related to the damage of the dopaminergic system of the striatum. 52HT can also regulate mood and memory . It is an inhibitory neurotransmitter and plays a central role in stability. Significant insanity can occur with 52HT receptor antagonists administered to animals . The results of this experiment showed that the levels of DA and 52HT in the brain of V B6- deficient rats were significantly decreased. VB6 affects the anabolism of DA and 52HT and its coenzyme as an amino acid decarboxylase. Gularte et al. found that VB6 deficiency before and after birth reduced dopamine decarboxylase activity in the striatum region of the brain at developmental stage. 52HT in the brain is a metabolite of tryptophan , and 52 hydroxytryptophan decarboxylase is its key enzyme. Some experiments have found that there is no significant change in 52HT in the brain of tryptophan alone . Only the addition of 52HT in VB6 brain can increase , suggesting that V B6 is a cofactor for the synthesis of 52HT by tryptophan metabolism . In conclusion , the results of this experiment show that VB6 deficiency can cause learning and memory impairment in rats , and the abnormal anabolic metabolism of monoamine neurotransmitters in brain tissue may be one of the reasons.