低浓度甲醛吸入对不同年龄Wistar大鼠海马脑片长时程增强的影响

目的探讨低浓度甲醛吸入后大鼠离体海马脑片长时程增强(LTP)的变化及此变化是否具有年龄差异性。方法选取健康Wistar大鼠32只。其中成年鼠和幼年鼠各12只,新生鼠8只。每个年龄段的大鼠随机分为对照组和甲醛染毒组。甲醛染毒组大鼠暴露于质量浓度为0.5 mg.m-3甲醛,染毒时间为每天2 h,连续30 d。染毒结束后制作离体海马脑片,利用膜片钳技术记录高频刺激(HFS)后海马脑片LTP,并分析兴奋性突触后场电位(fEPSP)的斜率和幅度变化。结果各年龄段甲醛染毒组在HFS后的第30分钟fEPSP的斜率和幅度均较同龄对照组降低。新生鼠中甲醛染毒组与对照组海马脑片HFS后30 min fEPSP的斜率分别为(118.1±9.7)%和(281.8±40.2)%,差异有统计学意义(P<0.01);在幼年鼠,甲醛染毒组与对照组海马脑片HFS后30 min fEPSP的斜率分别为(107.7±5.2)%和(289.5±64.7)%,差异有统计学意义(P<0.05);在成年鼠,甲醛染毒组与对照组海马脑片HFS后30 min fEPSP的斜率分别为(120.7±6.5)%和(197.9±38.1)%,无统计学差异(P>0.05)。新生鼠甲醛染毒组与其对照组海马脑片HFS后30 min fEPSP的幅度分别为(111.1±4.9)%和(293.4±46.8)%,差异有统计学意义(P<0.01);幼年鼠甲醛染毒组与其对照组海马脑片HFS后30 min fEPSP的幅度分别为(101.9±4.2)%和(266.9±51.0)%,差异有统计学意义(P<0.05);成年鼠甲醛染毒组与其对照组海马脑片HFS后30 min fEPSP的幅度分别为(122.9±4.2)%和(191.2±33.6)%,无统计学差异(P>0.05)。结论甲醛吸入染毒可抑制Wistar大鼠海马LTP的形成,且这种抑制作用具有年龄差异性,年龄越小,甲醛所造成的损伤越大。

Effect of Low - Level Formaldehyde Inhalation on Long Term Potentiation in Hippocampus of Rats at Different Ages

Objective To explore the effects of inhalation exposure to formaldehyde on long term potentiation(LTP) in the hippocampus of rats at different ages. Methods Thirty-two Wistar rats,including 12 adult rats,12 infant rats and 8 neonatal rats,were divided into 3 terms,respectively,according to their ages.Each term was delivered into control group and formaldehyde exposure group.The experimental groups were exposed to 0.5 mg·m-3 of formaldehyde,the inhalation exposure was carried out for 30 days,2 h per day.Isolated hippocampal slices and extracellular electrophysiological recording were applied to study the effect of formaldehyde on LTP.Field excitatory postsynaptic potentials(fEPSP) slope and amplitude after high-frequency stimulation(HFS) were used as the indexes to observe the change of LTP. Results The slops and amplitudes of fEPSP in formaldehyde exposure groups of all ages were decreased 30 min after HFS compared with control group.In the neonatal rats term,the fEPSP slopes of 30 min after HFS in formaldehyde exposure group and control group were(118.1±9.7)% and(281.8±40.2)%,and the difference between the 2 groups was significant(P<0.01).In the infant rats term,the slopes after HFS in exposure group and control group were(107.7±5.2)% and(289.5±64.7)%,and the difference was definite(P<0.05).In the adult rats term,the fEPSP slopes after HFS in formaldehyde exposure group and control group were(120.7±6.5)% and(197.9±38.1)%,and the difference was not obvious(P>0.05).In the neonatal rats term,the fEPSP amplitudes after HFS in formaldehyde exposure group and control group were(111.1±4.9)% and(293.4±46.8)%,the difference between the 2 groups was significant(P<0.01).In the infant rats term,the amplitudes after HFS in exposure group and control group were(101.9±4.2)% and(266.9±51.0)%,and the difference was definite(P<0.05).In the adult rats term,the amplitudes after HFS in formaldehyde exposure group and control group were(122.9±4.2)% and(191.2±33.6)%,and the difference was not obvious(P>0.05). Conclusion Formaldehyde inhalation can suppress LTP induction in the rat hippocampus in different ages,the younger,the more sensitive to formaldehyde.