Effects Of Doping On The Histological Structure Of Cerebral Temporal Lobe Cortex, Related Enzyme Activities And Learning And Memory During The Developmental Mice

Objective1)To explore the possible mechanism of heroin toxicity on the brain during the developmental mice, The structure of cerebral temporal lobe cortex and activities of adenosine deaminase (ADA),succinate dehydrogenase (SDH),nitric oxide synthase (NOS) and glutathione (GSH) of developmental mice were studied.2)To investigate effects of heroin and ephedrine on the structure of cerebral temporal lobe cortex and capability of learning and memory, filial mice were given injection of heroin and ephedrine, and the structure of cerebral temporal lobe cortex and capability of learning and memory were studied.Methods1)36 pregnant mice from the experimental groups at the eighth day began to be continuously injected with three different concentrations (1.0g/L,1.5g/L and 2.0g/L) of heroin, 12 pregnant mice from the control group were injected with the same amount of saline until the birth of filial mice. Cerebral weight of filial mice was weighted. And it was observed that the changes of the cerebral temporal lobe cortex of filial mice by bio-microscopy,and detected that the activities of ADA,SDH,NOS and GSH by colorimetry at embryo 15 days and postnatal ages of 1 day,7 days,15 days from all experimental groups.2)36 filial mice from heroin were given intraperitoneal injection of heroin by gradually increase of doses, 36 filial mice from ephedrine group were injected with ephedrine by gradually increase of doses, and 36 filial mice from the control group were injected with the same amount of saline. The filial mice behavior changes were observed by bait maze. In the same time, the changes of the cell structure of cerebral temporal lobe cortex were observed by light microscope and transmission electron microscope. Expression of Bax protein and keratinocyte growth factor(KGF) was measured by immunohistochemical method, and the ChAT activity was detected by colorimetry.Results 1)Heroin had some adverse effects on cerebral weight of filial mice after injecting heroin in pregnant mice. The cerebral weight of experimental group was significantly lighter than that of control group.2)The development of filial cerebral was affected by heroin. The structure of filial cerebral temporal lobe of experiment group was not clear. The thickness of filial cerebral decreased and the number of neurons reduced except those in the cerebral temporal lobe cortexâ…¥at embryo15 days and postnatal 1 day.3)Heroin had effects on activities of ADA, SDH, NOS and GSH. Compared with the control group,ADA,SDH and NOS activities in brain increased while GSH activity decreased significantly at embryo 15 days after administration of heroin (P <0.01 or P <0.05),but the recovery of these activities at postnatal 15 days varied with different doses. All of these activities subsequently recovered to the normal level slowly in heroin administration (1.0 g/L);Activities of NOS and SDH also recovered to the normal level while others remained significantly affected at the dose of 1.5g/L;ADA,SDH and NOS activities were still higher and GSH activity were lower than that of the control in 2.0g/L group. Results of Two-Way ANOVA indicated that dose contributed more to heroin-induced brain damage than treatment time.4) Heroin and ephedrine had some effects on learning and memory of filial mice. Total test times, error frequency and total test time of bait maze in the heroin group and ephedrine group were significantly higher than those in the control group (P < 0.05 or P < 0.01) except those at 5 days in the ephedrine group (P > 0.05), and the above-mentioned three indexes of the heroin group were significantly higher than those of the ephedrine group (P < 0.05 or P < 0.01). Total test times and error frequency of bait maze increased by the increase in doses of heroin and ephedrine.5)Heroin and ephedrine had effect on the ChAT activity of filial mice's cerebral temporal lobe cortex. After administration of heroin and ephedrine at 5,10,15,20 days, ChAT activity was lower than that of the control group (P < 0.05 or P < 0.01). Inhibition rate of ChAT activity increased by the increase in doses of heroin and ephedrine. Inhibition rate of ChAT activity in heroin group was higher than that in ephedrine group from 5 days to 20 days.6)Heroin and ephedrine had some effects on microstructure of filial mice's cerebral temporal lobe cortex. After administration of heroin and ephedrine at 5,10,15,20 days, the dendrites and axon of pyramidal neurons in cerebral temporal lobe cortex were atrophied and the cell bodies became small. The number of apoptotic or necrotic cells was significantly higher than that of the control group (P < 0.05 or P < 0.01), and the above-mentioned two indexes of the heroin group were significantly higher than those of the ephedrine group (P < 0.05 or P < 0.01). The number of apoptotic or necrotic cells increased by the increase in doses of heroin and ephedrine.7)Heroin and ephedrine had effects on expression of Bax protein and KGF in cerebral temporal lobe cortex. After administration of heroin and ephedrine at 5,10,15,20 days, the number of Bax protein- and KGF-immunopositive neurons was significantly higher than that of the control group(P < 0.05 or P < 0.01), and the above-mentioned two indexes of the heroin group were significantly higher than those of the ephedrine group (P < 0.05 or P < 0.01). The number of Bax protein- and KGF-immunopositive neurons increased by the increase in doses of heroin and ephedrine.8)Heroin and ephedrine had some effects on ultrastructure of filial mice's cerebral temporal lobe cortex. With the doses of heroin and ephedrine increasing,nuclear membrane lost normal round contour, and the structures of organelles showed abnormal or vacuolar. The matrix around capillary dissolved or were destructed, and capillary lumen became narrow. The synaptic vesicles reduced.Conclusion1) After injecting heroin in pregnant mice, the development of filial mice's brain was affected for long term. Exposure to heroin at medium and late pregnancy stage had toxic effects on the neurons migration in the filial mice's brain. Cerebral weight of filial mice, thickness of each cerebral temporal lobe cortex and number of neurons were still lower than that of the control group at postnatal 15 days, which might be the extending results of direct toxicity of heroin and its metabolites on embryonic neurons.2)After injecting heroin in pregnant mice, the activities of ADA,SDH,NOS increased and GSH activity decreased. The damage of the histological structure of filial mice's brains might be correlated with the changes of ADA,SDH,NOS and GSH activities in mice's brain. 3)After administration of heroin and ephedrine, the activity of ChAT in cerebral temporal lobe cortex decreased. Cerebral temporal lobe cortex might play an important role in the formation of capability of learning and memory in filial mice.4)Heroin and ephedrine had effects on the histological structure of filial mice cerebral temporal lobe cortex. Positive expression of Bax protein and KGF enhanced. With the concentration increasing, the extent of damage of cerebral temporal lobe cortex also increased, which showed an evident logarithm dose-effect relationship.5)Heroin and ephedrine had great effect on learning and memory in filial mice, and this effects would be related with the damage of the histological structure of cerebral temporal lobe cortex and low activity of ChAT. With the concentration increasing, the extent of damage of learning and memory in filial mice also increased.