Inhibitive effect of aluminium on evoked potentials in hippocampal CA3 region in rats and the relationship with cholinergic and gamma-aminobutyric acid system
- VernacularTitle:铝对大鼠海马CA3区诱发电位的抑制及其与胆碱能、γ-氨基丁酸系统的关系
- Author:
Jianfeng HU
;
Hongmei XIAO
;
Ai LI
- Publication Type:Journal Article
- From:
Chinese Journal of Tissue Engineering Research
2005;9(9):218-221
- CountryChina
- Language:Chinese
-
Abstract:
BACKGROUND: As indicated by previous researches, aluminium (Al) could affect learning and memory of animals through many approaches in cluding affecting the stable status of intracellular calcium, decreasing protein kinase C(PKC) activity, and affecting the release of glutamic acid(Glu) . The formation of long-term potentiation(LTP) weakens in hip pocampal CA3 region of rats fed by forage containing Al. It could be found that Al would weaken evoked potential(EP) in hippocampal CA3 region and inhibit LTP formation, which might be related with the damaging effect of Al on L-Arg-NO approach through further application of acute Al administration, i.e., AlCl3 is directly injected into hippocampal CA3 region by microinjection.OBJECTIVE: To investigate the damaging effect of Al on learning and memory, and its correlation with cholinergic system and gamma-aminobutyric acid (GABA) system.DESIGN: A completelyrandomized controlled verifying study based on the experimental animals.SETTING: Department of psychology in a university and the medical college of an occupational technology college.MATERIALS: The study was conducted in the Laboratory of Neuro-Electrophysiology, the Faculty of Physiology, Tongji Medical College,Huazhong University of Science and Technology between September 2000 and April 2001. Totally 68 SD rats of ordinary grade in either gender with a body mass between 150 g and 250 g were obtained from the Department of Experimental Animals of Tongji Medical College, Huazhong University of Science and echnology.INTERVENTIONS: SD rats were randomly divided into 9 groups including normal NS ( NS ) control group ( n = 6): 1 μL of NS was injected twice ( 1 minute interval) into hippocampal CA3 region by microinjection; NS + AlCl3 group( n = 6): 1 μL of NS and 0.5 mol/L of AlCl3 were injected(1 minute interval) into hippocampal CA3 region by microinjection;NS + Tac group( n = 6): 1 μLof NS and 1 × 10-9 mol/L of Tacrine were injected in turn into hippocampal CA3 region by microinjection; NS + Bic group(n=6): 1 μL of NS and 1 × 10-3 mol/L of Bicuculline were injected in turn into hippocampal CA3 region by microinjection; Tac +AlCl3 group: 1 μL of 1 × 10-9 mol/L( n =8),1 × 10-10 mol/L ( n = 6) and 1 × 10-8 mol/L of Tacrine were firsdy injected into hippocampal CA3 region by microinjection, and 1 μL of 0. 5 mol/L AlCl3was injected 1 minute later; Bic + AlCl3 group: 1 μL of 1 × 10-3 mol/L( n = 9) and 1 × 10 -4 mol/L( n = 7) of Bicuculline were firstly injected into hippocampal CA3 region by microinjection, and 1 μL of 0.5 mol/L AlCl3 was injected 1 minute later. Population spike(PS) in hippocampal CA3 region was recorded after using single pulse to stimulate perforating fiber(PF). When PS became stable, medication was injected into hippocampal CA3 region to observe the impacts of Al on EP in hippocampal CA3 region and the impacts of some central transmitters on the effect of Al in in hibiting PS.MAIN OUTCOME MEASURES: PS evoked in hippocampal CA3 region;the impacts of Al on EP in CA3 region and the impacts of some central transmitters on the effect of Al in inhibiting PS. RESULTS: ① After the application of 0.5 mol/L of AlCl3 in hippocampalCA3 region by microinjection, the recorded amplitude of PS reduced to peakat 1 minute, which accounted for(33.8 ± 11. 0) % of the level beforemedication( n = 6). The inhibitive effect of AlCl3 lasted for 120 minutes. ② After the pre-application of 1 × 10-9 mol/L of Tacrine(cholinesterase in hibitor) into CA3 region by microinjection and the application of AlCl3 at oneminute later, it was found that Tacrine antagonized the inhibitive effects ofAlCl3 on PS within 1 to 30 minutes( n = 8) . Its antagonism would extend to60 minutes if 1 × 10-8 mol/L of Tacrine was administrated( n = 6) . How ever, the antagonism of 1 × 10-10 mol/L of Tacrine was weaker than that of 1×10-9 mol/L group within 3-5 minutes(n=6) ③ After thepre-application of 1 × 10-3 mol/L of Bicuculline into CA3 region by mi croinjection and the application of AlCl3 at one minute later, Bicucullinecould partially weaken the effects of AlCl3 within 1 to 20 minutes( n = 9). CONCLUSION: Al of certain concentration can inhibit the evoked PS am plitude in hippocampal CA3 region; Tacrine can antagonize Al' s effects andits antagonism might be related with dose. Hence, the inhibitive effects of Almight be related with the damage in Ach transmitter system. The applicationof Bicuculline, a GABAA inhibitor, also can weaken the PS inhibitive effectsof Al, which indicates that the inhibitive effect of Al also might be effective through GABA approach.
