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. 2021 Oct 19;22(20):11254. doi: 10.3390/ijms222011254

Figure 5.

Figure 5

Inhibition of GABAA and GABAB receptors downregulates GABA-mediated IGF-1 and IGF-1R expression in preosteoblast MC3T3-E1 cells. MC3T3-E1 cells (1 × 104 cells/mL) were treated with 5 µM each of (A,D) bicuculline, (B,E) CGP 46381, and (C,F) TPMPA 2 h before treatment with 10 mM GABA for seven days. Total RNA was extracted, and RT-PCR was performed to determine the expression level of IGF-1 and IGF-1R. Glyceraldehyde 3-phosphate dehydrogenase gene (GAPDH) was used as an internal control. The expression of IGF-1 and IGF-1R relative to that of GAPDH level was determined (bottom). In a parallel experiment, cell-free supernatants were collected, and ELISA was conducted. Significant differences among the groups were determined using Student’s t-test. All data are presented as mean ± standard error of the mean (*** p < 0.001). N.S., non-significant.