D description on the CPP internalization 5-HT4 Receptor Antagonist supplier mechanisms, along with other properties which include stability, toxicity and immunogenicity have been reviewed elsewhere [199]. Here we concentrate on use of CPPs for delivery of proteins to CNS. Schwarze and colleagues published a seminal function demonstrating capacity of CPP to deliver proteins across BBB [200]. In their study the NH2-terminal TAT (477)-galactosidase fusion protein (120 kDa) injected i.p. in mice was detected by immunochemical staining initially at 2 hr in brain microvessels then at four hr in brain parenchyma. No PK studies have been performed. Nonetheless galactosidase activity was visualized in sagittal and coronal brain sections as well as in liver, kidney, lung and heart (myocardium) and spleen. TAT did not seem to disrupt BBB as the Evan’s blue albumin complexes co-injected with TAT have been excluded in the brain tissues. Subsequently, TAT peptide was fused with GDNF and injected i.p. in a mouse model of PD. The fusion protein crossed the BBB and reached substantia nigra as was shown by immunohistochemical staining. Nonetheless, the therapy did not avert the loss of dopaminergic neurons in PD mice, possibly since the level of the fusion protein delivered for the target website was not enough [201]. A TAT-based system was also made use of to deliver Bcl-xL protein, a well-characterized death-suppression molecule, to the CNS for therapy of stroke. Intraperitoneal injection of TAT and Bcl-xL fusion protein resulted in a robust protein transduction in neurons, plus a dose-dependent reduce of cerebral infarction in a mouse middle cerebral artery occlusion (MCAO) model of ischemic stroke [202]. Similarly, a decreased infarct volume and neurological deficits have been observed after i.v. injection of TAT-Bcl-xL fusion protein 1 hr. just before or instantly right after the ischemia induced within a rat MCAO model [203]. A current study reported that TAT-leptin fusion protein was i.v. injected to mice fed with high-fat diet program. Immunohistochemical stainingNIH-PA Author OX1 Receptor Purity & Documentation manuscript NIH-PA Author Manuscript NIH-PA Author ManuscriptJ Manage Release. Author manuscript; available in PMC 2015 September 28.Yi et al.Pagesuggested boost in leptin accumulation in hypothalamus within the TAT-leptin treated mice, in comparison with the unmodified leptin or saline-treated animals. Importantly, TAT-leptin also prevented body-weight obtain more efficiently in comparison to leptin [204]. Cai et al. recently described good effects of TAT-mediated delivery of neuroglobin (Ngb) on focal cerebral ischemia outcome in mice [205]. Immediately after i.v. injection the TAT-Ngb fusion protein was detected in mice brain tissues by immunohistochemistry and western blotting. The group treated with TAT-Ngb two hr. before MCAO showed smaller sized brain infarct volume and enhanced neurologic outcomes when compared with the control groups. Furthermore, the group treated with TAT-Ngb right after MCAO and reperfusion showed significantly improved neuronal survival inside the striatum, when compared with the controls [205]. In addition to TAT some other CPPs, such as Syn-B vectors and Rabies virus glycoproteinderived peptide (RDP), were also shown to provide small molecules and proteins across BBB [206, 207]. For instance, Xiang et al reported efficient hippocampus targeting by a galactosidase-RDP fusion protein [206]. Interestingly, a straightforward mixing of a protein with CPP also improved delivery of several proteins which include -galactosidase, human IgG and IgM to mouse brain [208]. Having said that, CPP have displayed different toxicities includin.