Figure 3. MPTP and L-DOPA affect progenitor cells in the DG.

(A) Fluorescent Immunostaining of cells in the DG for BrdU and BLBP. Bracketed areas in the top row are presented at higher magnification in the bottom rows. QNPs are seen as BrdU⁺BLBP⁺ radial glia-like cells with a long basal process (white arrows), ANPs as BrdU+BLBP⁺ and BrdU⁺BLBP⁻ compact cells with the basal process (white arrowheads), and OPCs as BrdU⁺BLBP⁺ and BrdU+BLBP⁻ multiprocess cells (yellow arrowheads). Scale bars are 100 μm in the top row and 10 μm in the middle and bottom rows.

(B) MPTP and MPTP+L-DOPA treatments increased cell proliferation in the molecular layer of the DG and stratum lacunosum-molecular of the hippocampus; however, most of the dividing cells were negative for BLBP immunostaining. Scale bar is 10 μm.

(C) Quantification of BrdU⁺BLBP⁺ QNP cells in the DG 14 days after the treatment with saline (n=4), MPTP (n=9), L-DOPA (n=5), or MPTP+L-DOPA (n=9). The results for individual animals are shown as black dots; error bas show s.e.m. The variance of the values was significantly higher for the MPTP-exposed groups than for the saline- or L-DOPA-treated groups (p<0.0005 in the Bartlett's test), the distribution of values was not Gaussian, and the number of subjects in each groups was different, indicating the use of a non-parametric Kruskal-Wallis test with the Dunn multiple comparison post hoc test.

(D) Quantification of BrdU⁺BLBP⁺ and BrdU⁺BLBP⁻ ANP cells in the DG 14 days after the treatment with saline (n=4), MPTP (n=9), L-DOPA (n=5), or MPTP+L-DOPA (n=9). The results for individual animals are shown as black dots; error bas show s.e.m. The variance of the values was significantly higher for the MPTP-exposed groups than for the saline- or L-DOPA-treated groups (p<0.005 in the Bartlett's test), the distribution of values was not Gaussian, and the number of subjects in each groups was different, indicating the use of a non-parametric Kruskal-Wallis test (p=0.0307) with the Dunn multiple comparison post hoc test; p = 0.052 for MPTP and 0.058 for MPTP+L-DOPA.

(E) The fraction of BrdU-labeled QNP and ANPs cells among all BrdU-labeled cells in the SGZ. MPTP or L-DOPA treatments did not significantly change the fraction of BrdU-labeled QNP or ANPs cells (*p>0.05; Kruskal-Wallis test with the Dunn multiple comparison post hoc test).

(F) The number of BrdU⁺/BLBP⁺ QNP cells shows a significant linear relationship (r²=0.4615 p=0.0442) with the number of BrdU⁺-labeled cells in the MPTP+L-DOPA group.

(G) The number of BrdU⁺- labeled ANP cells shows a significant linear relationship (saline, r2=0.9988, p=0.0006; MPTP, r²=0.9989, p=0.0001; L-DOPA, r²=0.9761, p=0.0016; MPTP+LDOAP, r²=0.9973, p=0.0001) with the number of BrdU⁺-labeled cells in all animal groups.

(H) The loss of TH-positive dopaminergic neurons in the SNpc and cell division in the DG show a significant linear relationship in the MPTP+L-DOPA group (r²=0.4625; p=0.0438).