The Role Of Syntain1b-mediated Dopamine Receptor Changes In The Excitatory Activity Of Benzo[a]pyrene Induced Autonomic Activity

Benzo [a] pyrene(B[a]P)is the most common class of chemical pollutants in the environment,mainly through the respiratory tract,digestive tract and skin and mucous membranes into the human body,prolonged exposure Will accumulate in the body tissues and organs.It has been shown that B[a]P is neurotoxic,manifested in mental illness such as neonatal nervous system development,attention deficit hyperactivity disorder and ADHD;learning and memory and movement of adolescents;learning and memory and neurological function of occupational workers.B[a]P exposure to health hazards in many ways,chronic B[a]P exposure will cause abnormal changes in multiple systems of the human body,including nerve,breathing,digestion,immune system and so on.Compared with other organizations,nerve cells are non-renewable cells,it is very sensitive to the role of poison.Prehospital population reported that sub-chronic B[a]P exposure to children's nervous system damage,reflecting the brain function is inhibited,resulting in nerve tissue development disorders and mental retardation,reflected in the movement behavior,cognitive and learning and memory and so on.Through the animal experiments,we found that the number of steps in the rat step increased,the latency was shortened;the swimming time of the exposed group decreased.It has been reported that the effects of B[a]P or its metabolites on NMDA receptors are shown in hippocampus,cerebellum and amygdala in brain tissue,suggesting that B[a]P and its metabolites have an effect on the cerebellum.Studies have shown that the cerebellum is responsible for regulating muscle tone,maintaining physical balance and coordination of fine exercise,B[a]P exposure will lead to brain tissue quality lower than the blank group(P <0.01);electron microscopy under the morphine damage,Cerebellar neuron injury.The above suggests that the cerebellum may be one of the target organs of B[a]P toxic effects.After investigating and investigating the effects of B[a]P exposure on the cerebellum,the mechanism of B[a]P affecting animal movement coordination and self-activity is not yet clear.Objective :The effect of B[a]P subchronic exposure on the autonomic activity and exercise coordination ability of SD rats was investigated by behavioral open field experiment and footsteps experiment.And then from the perspective of neurotransmitter transmission process to explore the early B[a]P exposure caused by neurobehavioral changes in SD rat cerebellar tissue neurotransmitter transmission process related substances in the situation.Methods:1?30 male juvenile rats,aged 5 days were randomly divided into blank group,solvent group(peanut oil),B[a]P low-dose group(0.02 mg/kg),B[a]P medium-dose group(0.2 mg/kg)and B[a]P high-dose group(2.0 mg/kg),the rats were observed and weighed once every day and intragastric administrated according to the weight for 7 consecutive weeks.2?The open filed test and foot printing test were conducted to evaluate the spontaneous activity and motor coordination of rats.The number of crawling total lattice,the number of upright and the number of fecal particles in the open field experiment were recorded,and the corresponding indexes such as the heel footprint in the footsteps were recorded.3?The cerebellum tissues was stained with H&E.4?Electron microscope observation: The changes of nerve cells and synaptic clearances in cerebellum;5?Immunohistochemistry and immunoblotting were used to detect the expression of presynaptic membrane protein Syntaxin1 B and neurotransmitter dopamine DRD1 in cerebellum.Results :1?During the exposure period,SD rats in each group were generally in good condition.After the treatment,the body weight of each exposed group was significantly lower than that in the blank group rats(P<0.05).2?The total number of crawling lattice and straight times in each exposed group was significantly increased when compared with the blank group and the solvent group in the open field test(P<0.05).However,there were no significant differences of step width,step size,gait changes and the angle changes between the five groups in the foot printing test(P>0.05).3?HE staining showed that the cerebellum of the group was well constructed and could see the normal leaves and lamellar structure.Compared with the control group,there was no significant change in the cell layer of cerebellar tissue in the exposed group,while the cytoplasmic staining of PC cells was pale and uneven.The cell layer was damaged,the width was shortened,the number of cells decreased,High dose group is particularly evident.4?Electron microscopy showed that the synaptic clearances of middle and high dose groups increased(P <0.000)compared with the control group after 7 weeks of exposure to B [a] P;5 ? Immunohistochemical results showed that synaptic membrane protein Syntaxin1 B and neurotransmitter dopamine DRD1 were expressed in cerebellar tissue.Western-blot results showed that Syntaxin1 B protein and DRD1 protein expression increased.Conclusion:After sub-chronic B[a]P exposure,SD rats in the growth and development of weight loss;to promote SD rats autonomic activity,but its role in the coordination of movement is not obvious;damage the normal form of cerebellar tissue;Cerebellar neurotransmitter dopamine DRD1 and synaptic membrane protein Syntaxin1 B protein expression changes.