Article Figures & Data
Figures
- Figure 1.
BDNF mRNA is not present in cells of the transgenic knock-outs used as nerve graft donors. A, Based on results of FISH, BDNF mRNA is present in the cells in the ventral horn of the spinal cord of untreated wild-type mice. B, Two weeks of treadmill training (TT) resulted in increased labeling of BDNF mRNA-positive cells in wild-type mice. C, No BDNF mRNA was detected in tissues collected from tam-Cre::BDNFf/f mice, regardless of training condition. D, BDNF allele deletion for the CNTF-Cre::BDNFf/f mice was assessed using a Cre reporter mouse, termed tomato. All cells in the sciatic nerve of the tomato mouse are tomato fluorophore-positive. E, After expression of Cre-recombinase, Cre+ cells express green fluorescent protein. The presence of green fluorescence in presumptive Schwann cells indicates that Cre recombinase is active in cells of the sciatic nerve of CNTF-Cre-expressing mice. These data support the idea that Cre activity in CNTF+ cells in CNTF-Cre::BDNFf/f mice removes BDNF from CNTF+ cells.
- Figure 2.
Profiles of axons growing into grafts lacking BDNF (tam-Cre::BDNFf/f treated and CNTF-Cre::BDNFf/f) are significantly shorter than controls. A, C, The cumulative frequency histogram of profile lengths of axons growing into tam-Cre::BDNFf/f-treated (A) and CNTF-Cre::BDNFf/f (C) grafts are significantly shifted to the left compared with controls, indicating an overall decrease in profile lengths. For all cumulative histograms, the size of each symbol is proportional to the SEM of that data point and the dashed line indicates the 50th percentile. B, The median length of axon profiles growing into tam-Cre::BDNFf/f-treated grafts are significantly reduced compared to those growing into WT and untreated grafts (**p ≤ 0.0006) and tam-Cre::BDNFf/w Tx grafts (*p ≤ 0.0001). D, The median length of axon profiles from CNTF-Cre::BDNFf/f-treated grafts are significantly reduced compared with the lengths of regenerating axon profiles growing into grafts containing BDNF (**p ≤ 0.0001 compared to WT, *p ≤ 0.002 compared to CNTF-Cre::BDNFf/w). For all bar graphs, circles represent individual data points and error bars represent ±SEM.
- Figure 3.
Two weeks of treadmill training (TT) or the administration of BDNF to the surgical repair site significantly enhances axon profile lengths. A, The cumulative histogram of profile lengths of axons growing into wild-type or CNTF-Cre::BDNFf/f grafts treated with rhBDNF is shifted significantly to the right of those from mice whose nerves were repaired with either untreated wild-type or CNTF-Cre::BDNFf/f grafts, suggesting that their axons are significantly longer. B, The median axon profile lengths are significantly longer into BDNF-treated wild-type and CNTF-Cre::BDNFf/f grafts compared with controls (*p ≤ 0.0001). C, The cumulative histograms of the lengths of axon profiles in wild-type and CNTF-Cre::BDNFf/f mice are shifted significantly to the right of those of control mice after treadmill training, indicating a significant increase in the lengths of all regenerating axon profiles. D, The median axon profile length of wild-type and CNTF-Cre::BDNFf/f is significantly increased after treadmill training (*p ≤ 0.0001). E, Low-magnification images of representative nerves from thy-1-YFPH hosts 2 weeks after nerve repair. The white bar across the nerve indicates the site of surgical repair.
- Figure 4.
Axons lacking BDNF do not significantly regenerate into BDNF-lacking grafts regardless of the training. A, The cumulative histograms of axon profile lengths of SLICK::BDNFf/f and SLICK::BDNFf/w axons growing into tam-Cre::BDNFf/f Tx grafts are shifted significantly to the left of those of controls, suggesting that these axons are significantly shorter than those growing in WT grafts (p ≤ 0.04). B, The median axon profile lengths are significantly shorter into BDNFf/f grafts compared with WT (*p ≤ 0.009; **p ≤ 0.0001). C, The cumulative histogram of the lengths of axon profiles of YFP+ SLICK::BDNFf/f axons is significantly shifted to the left when nerves are repaired with BDNFf/f grafts and hosts are treadmill-trained for 2 weeks postrepair (p ≤ 0.01). D, The median axon profile length of SLICK::BDNFf/f axons growing into BDNFf/f grafts remains significantly decreased after treadmill training compared with SLICK::BDNFf/f axons growing into a WT graft (p ≤ 0.0001). E, Low-magnification images of representative nerves from trained and untrained SLICK::BDNFf/f hosts 2 weeks after nerve repair. The white bar across the nerve indicates the site of surgical repair.
Tables
Genotype Treatment tamoxifen (Tx) or saline (UT) Host mouse or nerve donor BDNF alleles WT, tomato Tx or UT Donor Systemic BDNF +/+ thy-1-YFP-H UT Host Systemic BDNF +/+ Tam-Cre::BDNFf/f Tx Donor Systemic BDNF −/− Tam-Cre::BDNFf/f UT Donor Systemic BDNF +/+ Tam-Cre::BDNFf/w Tx Donor Systemic BDNF +/− Tam-Cre::BDNFf/w UT Donor Systemic BDNF +/+ CNTF-Cre::BDNFf/f UT Donor CNTF+ cells BDNF −/−, other cells BDNF+/+ CNTF-Cre::BDNFf/w UT Donor CNTF+ cells BDNF +/−, other cells BDNF+/+ SLICK::BDNFf/f Tx Host YFP+ neurons BDNF −/−, other cells BDNF +/+ SLICK::BDNFf/w Tx Host YFP+ neurons BDNF +/−, other cells BDNF +/+
