Effects of lead exposure on nitric oxide synthase activity in different brain regions of developmental rat

Objective To observe the influence of low-level lead exposure on the activity of nitric oxide synthase(NOS) in different brain regions of rat. Methods By establishing a series of rat models exposed to different low levels of lead(drinking water containing 0.025%,0.050%,0.075% of lead acetate) during developing period, NOS activities in hippocampus,cerebellum,cerebral cortex and brain stem were studied. Results On the 21st day after birth,NOS activities in hippocampus of three levels of lead exposed groups[(1.53±0.20),(1.66±0.23),(1.88±0.32)U/mg pro respectively],and in cerebellum[(0.87±0.24),(0.85±0.09),(0.91±0.18) U/mg pro respectively] were significantly lower than those of control group[(2.36±0.18),(1.41±0.18)U/mg pro,respectively, P 0.01].NOS activities in cerebral cortex of 0.075% group [at 7,14,21 d of age[(1.29± 0.14) ,(1.03±0.15),(0.69±0.10)U/mg pro] were significantly lower than those in control group[(2.54± 0.31) ,(1.64±0.22),(1.24±0.14)U/mg pro respectively],and 0.025% group[(2.42±0.19),(1.59± 0.17), (1.27±0.12)U/mg pro respectively],and 0.050% group[(2.56± 0.53), (1.77±0.19),(1.24± 0.10) U/mg pro respectively, P 0.05] .There were no significant differences among control,0.025%,and 0.050% groups( P 0.05).Lead exposure had no influence on NOS activity in brain stem at the same age( P 0.05). Conclusion NOS activities in hippocampus,cerebellum and cerebral cortex were inhibited by low level lead exposure and the degree of the effect was related to Pb exposure time and(or) level of Pb exposed.