Citation:Liu H,Gao PF,Xu HW,Liu MM,Yu T,Yao JP,Yin ZQ.Perineuronal nets increase inhibitory GABAergic currents during the critical period in rats.Int J Ophthalmol 2013;6(2):120-125,doi:10.3980/j.issn.2222-3959.2013.02.02
Perineuronal nets increase inhibitory GABAergic currents during the critical period in rats
Received:October 23, 2012  Revised:March 10, 2013
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DOI:10.3980/j.issn.2222-3959.2013.02.02
Key Words:gamma-aminobutyric acid receptor  plasticity  visual cortex  development  postsynaptic currents  chondroitinase ABC  chondroitin sulfate proteoglycans  whole-cell patch recording
Fund Project:National Natural Sciences Foundation of China (No. 81070749)
                    
AuthorInstitution
Hui Liu Southwest Eye Hospital, Southwest Hospital, Third Military Medical University, Chongqing , China;
Key Lab of Visual Damage and Regeneration & Restoration of Chongqing, Chongqing , China
Peng-Fen Gao Southwest Eye Hospital, Southwest Hospital, Third Military Medical University, Chongqing , China;
Key Lab of Visual Damage and Regeneration & Restoration of Chongqing, Chongqing , China
Hai-Wei Xu Southwest Eye Hospital, Southwest Hospital, Third Military Medical University, Chongqing , China;
Key Lab of Visual Damage and Regeneration & Restoration of Chongqing, Chongqing , China
Ming-Ming Liu Southwest Eye Hospital, Southwest Hospital, Third Military Medical University, Chongqing , China;
Key Lab of Visual Damage and Regeneration & Restoration of Chongqing, Chongqing , China
Tao Yu Southwest Eye Hospital, Southwest Hospital, Third Military Medical University, Chongqing , China;
Key Lab of Visual Damage and Regeneration & Restoration of Chongqing, Chongqing , China
Jun-Ping Yao Southwest Eye Hospital, Southwest Hospital, Third Military Medical University, Chongqing , China;
Key Lab of Visual Damage and Regeneration & Restoration of Chongqing, Chongqing , China
Zheng-Qin Yin Southwest Eye Hospital, Southwest Hospital, Third Military Medical University, Chongqing , China;
Key Lab of Visual Damage and Regeneration & Restoration of Chongqing, Chongqing , China
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Abstract:
      AIM: To investigate inhibitory γ-aminobutyric acid (GABA) ergic postsynaptic currents (IPSCs) and postsynaptic currents (PSCs) in layer IV of the rat visual cortex during the critical period and when plasticity was extended through dissolution of the perineuronal nets (PNNs).

    METHODS:We employed 24 normal Long-Evans rats to study GABAA-PSC characteristics of neurons within layer IV of the visual cortex during development. The animals were divided into six groups of four rats according to ages at recording:PW3 (P21-23d), PW4 (P28-30d), PW5 (P35-37d), PW6 (P42-44d), PW7 (P49-51d), and PW8 (56-58d). An additional 24 chondroitin sulfate proteoglycan (CSPG) degradation rats (also Long-Evans) were generated by making a pattern of injections of chondroitinase ABC (chABC) into the visual cortex 1 week prior to recording at PW3, PW4, PW5, PW6, PW7, and PW8. Immunohistochemistry was used to identify the effect of chABC injection on CSPGs. PSCswere detected with whole-cell patch recordings, and GABAA receptor-mediated IPSCs were pharmacologically isolated.

    RESULTS:IPSC peak current showed a strong rise in the age-matched control group, peaked at PW5 and were maintained at a roughly constant value thereafter. Although there was a small increase in peak current for the chABC group with age, the peak currents continued to decrease with the delayed highest value at PW6, resulting in significantly different week-by-week comparison with normal development. IPSC decay time continued to increase until PW7 in the control group, while those in the chABC group were maintained at a stable level after an initial increase at PW4. Compared with normal rats, the decay times recorded in the chABC rats were always shorter, which differed significantly at each age. We did not observe any differences in IPSC properties between the age-matched control and penicillinase (P-ase) group.However, the change in IPSCs after chABC treatment was not reflected in the total PSCs or in basic membrane properties in layer IV of the rat visual cortex.

    CONCLUSION:Our results demonstrate that rather than rapidly increasing during the critical period for neuronal plasticity, IPSCs in layer IV of rat visual cortex are maintained at an immature level when PNNs are removed by chABC. This suggests that GABA receptor maturation involves the conformation of the CSPGs in PNNs.

PMC FullText Html:http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3633745/
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