Fig 1.
Activin A protects nigral neurons against MPTP-induced cell death.
(A) Experimental timeline. (B) Representative images of TH-immunoreactive neurons in the substantia nigra pars compacta (SNpc). (C) Representative images of NeuN-immunoreactive neurons in the SNpc. (D) Stereological quantification of TH-immunoreactive neurons in SNpc demonstrates activin A protects dopaminergic neurons against MPTP toxicity. (E) Stereological quantification of NeuN-immunoreactive neurons in the SNpc demonstrates activin A protects total neuron numbers against MPTP induced toxicity. All values represent the mean ± SEM. *p<0.05, **p<0.01, ***p<0.001. Scale bar represents 200μm. N = 5/group.
Fig 2.
Activin A does not alter striatal dopamine levels following MPTP.
HPLC-ECD quantification of catecholamine levels revealed that activin A does not alter striatal DA (A), DOPAC (B), or HVA (C) levels following MPTP administration. Activin A did not alter the catabolism of DA to HVA (D) following MPTP administration. Activin A significantly increased striatal NE levels (E). All values represent the mean ± SEM. *p<0.05, ***p<0.001. N = 5-7/group.
Fig 3.
Activin A alters TH phosphorylation but not striatal DAT following MPTP.
Western blot analysis of striatal protein extracts from animals receiving PBS or activin A 8 days after MPTP. Representative bands of TH, GAPDH and (A) p-TH(ser40) and (C) p-TH(ser31) expression. Quantification of p-TH(ser40)/TH (B) and p-TH(ser31)/TH (D) protein expression normalized to GAPDH (n = 6/group). (E) Representative bands of DAT and GAPDH expression. (F) Quantification of DAT protein expression normalized to GAPDH. All values represent the mean ± SEM. *p<0.05, ***p<0.001. N = 6-7/group.
Fig 4.
Activin A protects midbrain neurons up to 8 weeks post-MPTP.
Stereological quantification demonstrates activin A protects SNpc dopaminergic neurons (A) and total neuron numbers (B) against long-term MPTP induced toxicity. No significant effect of activin A on striatal DA (C), DOPAC (D) or HVA levels (E) the turnover of DA to HVA (F) or striatal NE levels (G) was found 8 weeks post-MPTP. (H) Representative images of DAT and GAPDH expression. (I) Western blot analysis of striatal protein extracts revealed activin A does not protect DAT expression 8 weeks post-MPTP. All values represent the mean ± SEM. *p<0.05 **p<0.01, ***p<0.001. N = 3-13/group.
Fig 5.
Activin A decreases MPTP and LPS-induced inflammation.
Stereological quantification of the left SNpc demonstrated activin A significantly decreased the number of GFAP-immunoreactive cells (A) and Iba1-immunoreactive cells (B) in the SNpc following MPTP. (C) Timeline detailing LPS experimental procedures. Stereological quantification demonstrated activin A significantly reduces the LPS-induced increase in GFAP (D) and Iba1 (E) positive cells and subsequent loss of TH (F) and NeuN (G) positive cells. (H) Representative images of DAT and GAPDH expression. (I) Western blot analysis of striatal protein extracts revealed LPS does not alter DAT expression. All values represent the mean ± SEM. *p<0.05, **p<0.01, ***p<0.001. N = 3-5/group.