Effect of monocular form deprivation during critical period on the density of NRG1 + and NRG1 – PV neurons in the mouse primary visual cortex

Objective  To investigate the effect of monocular form deprivation (MD) on the distribution density of neuregulin-1 (NRG1) ⁺ and NRG1 ^– parvalbumin (PV) neurons in the primary visual cortex of mice during the critical period of visual development.

Methods  Twelve healthy 28-day-old SPF male C57BL/6J mice were randomly divided into control group and MD group by the random number table method, with 6 mice in each group.After MD on postnatal day (P) 28, the MD group was fed until P32, while the control group was fed normally until P32.All mice were sacrificed by cervical dislocation after cardiac perfusion, and brain tissues were quickly collected.After fixation overnight, brain slices were subjected to PV and NRG1 immunofluorescence staining to observe and compare the differences in the distribution density of PV ⁺ , PV ⁺ /NRG1 ⁺ and PV ⁺ /NRG1 ^– neurons in both sides of the primary visual cortex (V1) area of the two groups.This study was conducted in accordance with the Regulations on the Administration of Experimental Animals (2017 Revision), and the study protocol was approved by the Institutional Animal Care and Use Committee of Tianjin Medical University (No.TMUaMEC2022004).

Results  Immunofluorescence staining showed that the density of PV ⁺ and PV ⁺ /NRG1 ⁺ neurons was (137.8±4.3), (108.8±4.1), (137.4±4.0)/mm ² in the contralateral V1 area of the control group, MD group and the ipsilateral V1 area of the MD group, and that of PV ⁺ /NRG1 ⁺ neurons was (112.0±4.6), (82.1±4.7) and (113.6±5.7)/mm ², respectively, with statistically significant overall differences ( F=15.88, 12.53; both P<0.001).PV ⁺ neuron density and PV ⁺ /NRG1 ⁺ neuron density in the contralateral V1 area of the MD group were significantly lower than in the control group and in the ipsilateral V1 area of the MD group (all P<0.001).There was no difference in PV ⁺ /NRG1 ^– neuron density between the two groups ( F=0.20, P>0.05).

Conclusions  PV ⁺ /NRG1 ⁺ neurons may be the main cell type regulating the development of primary visual cortex during the critical period.

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