Developmental properties of parvalbumin-positive gamma-aminobutyric acid interneurons and the effect of fluoxetine treatment and binocular form deprivation on them in the visual cortex of adult rats

Abstract:

AIM: To investigate the postnatal development of parvalbumin (PV)-positive gamma-aminobutyric acid (GABA) interneurons and the co-expression of perineuronal nets (PNNs) and PV in the visual cortex of rats, as well as the regulatory effects of fluoxetine (FLX) treatment and binocular form deprivation (BFD) on these indices. METHODS: Wistar rats were assigned to three experimental cohorts: 1) Age-related groups: postnatal week (PW) 1, PW3, PW5, PW7, and PW9; 2) FLX treatment duration groups: FLX 0W, FLX 2W, FLX 4W, FLX 6W, and FLX 8W; 3) Intervention groups: control (Cont), FLX, BFD, and BFD+FLX. The levels of PNNs, PV, and PNNs/PV co-expression in the visual cortex were detected and analyzed. RESULTS: The density of PV-positive cells and the co-expression of PNNs and PV increased gradually with the maturation of the visual cortex (b=0.960, P<0.01). The ratio of PV-positive cells surrounded by PNNs to total PV-positive cells (PNNs+/PV+/total PV+) was significantly decreased in the FLX 4W group (χ²=9.03, P=0.003). There was no significant difference in the PNNs+/PV+/total PV+ ratio between the FLX and BFD groups (χ²=1.08, P=0.161), but a significant difference was observed between the BFD+FLX group and the BFD group (χ²=5.82, P<0.01). CONCLUSION: The number of PV-positive neurons and PNNs-surrounded PV neurons in the rat visual cortex increases postnatally and reaches adult levels by postnatal week 7. Chronic FLX treatment downregulates these expressions. Combined 4-week FLX treatment and BFD exerts a more significant inhibitory effect on the PNNs+/PV+/total PV+ ratio than either intervention alone.