Effects Of Low-Level Formaldehyde Inhalation On Ltp And Expression Of Camk Ⅱ Mrna In The Hippocampus Of Rats With Different Ages

Objective To explore the change of long term potentiation (LTP) and the expression of CaMK Ⅱ in the hippocampus of rats with different ages after inhalation exposure to formaldehyde.Methods32Wistar rats, including12adult rats,12infantile rats and8neonatal rats, were divided into3terms, respectively, according to their ages. Each term was delivered into control group and FA exposure group. The experimental groups were exposed to0.5mg·m-3of formaldehyde, the inhalation exposure was carried out for30days,2h 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. Real-time quantitative RT-PCR was used to measure the expression level of CaMK Ⅱ mRNA in the neuron of hippocampus.Results In the neonatal rats term,the fEPSP slopes of30min after HFS of formaldehyde exposure group and control group were (118.1±9.7)%and (281.8±40.2)%,the difference between the two groups was significant (p<0.01). In the infantile rats term,the slopes after HFS of exposure group and control group were (107.7±5.2)%and (289.5±64.7)%,the difference was definite (p<0.05). In the adult rats term,the fEPSP slopes after HFS of formaldehyde exposure group and control group were (120.7±6.5)%and (197.9±38.1)%,the difference was not obvious (p>0.05). In the neonatal rats term,the fEPSP amplitudes after HFS of formaldehyde exposure group and control group were (111.1±4.9)%and (293.4±46.8)%,the difference between the two groups was significant (p<0.01). In the infantile rats term,the amplitudes after HFS of exposure group and control group were (101.9±4.2)%and (266.9±51.0)%,the difference was definite (p<0.05). In the adult rats term,the amplitudes after HFS of formaldehyde exposure group and control group were (122.9±4.2)%and (191.2±33.6)%,the difference was not obvious (p>0.05).The content of CaMK Ⅱ in control group was1.07±0.15,0.21±0.06in formaldehyde exposure group of the neonatal rats,the difference between the two groups was significantly (P<0.01).In the infantile rats term, the content of CaMK Ⅱ in control group was1.01±0.07,0.25±0.03in formaldehyde exposure group,the difference between the two groups was significantly (P<0.01). In the adult rats term, the content of CaMK Ⅱ in control group was1.02±0.10,0.45±0.10in formaldehyde exposure group,the difference between the two groups was significantly (P<0.01).Conclusion Formaldehyde inhalation can suppress LTP induction in the rat hippocampus in different ages, the younger, the more sensitive to formaldehyde, which might be related to the decrease of the expression of CaMK Ⅱ in the hippocampus.