The visual cortex plasticity of adult rat after binocular form deprivation by pattern visual evoked potential / 中华实验眼科杂志

ABSTRACT

Background The visual evoked potential (VEP) is an important functional index to assess visual cortex plasticity.Monocular form deprivation(MD) of rat is a classic model to study visual cortex plasticity change.Utilizing VEP technique record the shift of ocular dominance in adult rats model is of an important significance for explore the treating opportunities of amblyopia.Objective The present study was to observe the pattern VEP changes in different ages of Long-Evens rats and the adult rats after binocular form deprivation.Methods Thirty-six healthy SPF Long-Evens rats were divided into PW3,PW4,PW5,PW6 groups according to the postnatal weeks,and PW7 rats included 36 SPF Long-Evens rats.The left eye lids of the rats were sutured in PW3,PW6 and PW7 rats for 3,5,7 days respectively,and PVEP in both left and right eye were recorded to assess the rat age that visual cortex plasticity ended.Bilateral PVEP were recorded in PW7 rats,and the bilateral eyelids were sutured to establish the bilateral form deprivation models.The right eyes were opened in 7,10,14 days,and the left eyes were opened in the next 3,5,7 days respectively and the PVEPs were recorded again to find the shift of ocular dominance and whether binocular form deprivation induce the visual cortex plasticity in adult rats.Results The P100amplitudes of the left eyes were gradually declined and those of the right eyes were raised from 3 to 7 days after MD of the left eyes in rats of PW3 group in comparison with before MD ( P＜0.01 ).In PW6 groups,no significant changes in P100amplitudes of both the right and left eyes were found in the third day after MD,but significant raise in the right eyes and lowing in the left eyes were seen in the 5 and 7 days after MD in comparison with before MD(P＜0.01 ).No any P100changes in both eyes were found in 3-7 days after MD compared with before MD in PW7 rats (P＞0.05).The C/I ratio (contralateral VEP amplitude to ipsilateral VEP amplitude in occluded eyes) in the rats of PW3,PW4 and PW5 groups were 1.07±0.15,1.16±0.16 and 1.14±0.15 respectively in 3 days after MD,showing the significant lowing in comparison with before MD (2.69±0.45,2.58±0.4,2.62±0.32) (P＜0.01),but those of PW6 and PW7 were unchanged (2.80±0.48 vs 2.90±0.46,2.59 ±0.36 vs 2.90±0.46,P＞0.05 ),indicating the absence of ocular dominance plasticity in the adult rats.In rats of PW7 with binocular form deprivation for 14 days,a significant decrease was observed in the C/I ratio in rats with next MD for 3 days,demonstrating that the visual cortex plasticity was reactivated after 14 days of binocular form deprivation in PW7 rats( 1.33±0.18 vs 2.70±0.45,P＜0.01 ).Conclusions PVEP can be recorded in Long-Evens rats.It is a major index for identifying the shift of ocular dominance in the Long-Evens rats.Binocular form deprivation can reflect the visual cortex plasticity in the adult rats.