Improved Brain Uptake and Pharmacological Activity of Dalargin Using a Peptide-Vector-Mediated Strategy

Abstract

The blood-brain barrier restricts the passage of substances into the brain. Neuropeptides, such as enkephalins, cannot be delivered into the brain when given systemically because of this barrier. Therefore, there is a need to develop efficient transport systems to deliver these drugs to the brain. Recently, we have demonstrated that conjugation of doxorubicin or penicillin to peptide vectors significantly enhances their brain uptake. In this study, we have conjugated the enkephalin analog dalargin with two different peptide vectors, SynB1 and SynB3, to improve its brain delivery and its pharmacological effect. We show by in situ brain perfusion that vectorization markedly enhances the brain uptake of dalargin. We also show using the hot-plate model that this enhancement in brain uptake results in a significant improvement in the observed antinociceptive effect of dalargin. These results support the usefulness of peptide-mediated strategies for improving the availability and efficacy of central nervous system drugs.Brain delivery is one of the major challenges for the neuropharmaceutical industry since increasing number of hydrophilic therapeutic agents, such as anticancer drugs, antibiotics, and antiviral drugs are unable to cross the blood-brain barrier (BBB). The BBB represents a complex endothelial interface in vertebrates that separates the blood compartment from the extracellular fluid compartment of the brain parenchyma. The capillaries in the brain parenchyma possess a high electrical resistance due to tight junctions between the endothelial cells and also lack pores. Thus, the brain capillary endothelium behaves like a continuous lipid bilayer, and diffusion through this BBB layer is largely dependent on the lipid solubility of the drug. Because peptides are hydrophilic, biologically unstable, and large molecules, it is difficult for them to penetrate the BBB. Even though their brain uptake is not so high, some peptides and proteins are delivered into the brain by carrier-mediated transport, receptor-mediated transport, or adsorptive-mediated transport mechanisms. One of the problems associated with the inability of many peptides and proteins to accumulate in the brain in therapeutically meaningful amounts is the efflux transport systems. For example, it has been shown that the selective ␦-opioid receptors against [D-Pen 2 ,D-Pen 5 ]-enkephalin (DPDPE) has a poor BBB permeability that is explained in part by P-glycoprotein (P-gp)-mediated efflux, and DPDPE is also a substrate of the rat organic anion transporting polypeptide 2 (OATP2) and human OATP-A (Kakyo et al., 1999;Gao et al., 2000).To overcome the limited access of drugs to the brain, various strategies have been applied to direct central nervous system (CNS) drugs into the brain . Most of these methods are invasive, such as surgical implantation of an intraventricular catheter followed by drug infusion into the ventricular compartment, transient opening of the tight junctions by the intracarotid infusion of a hypertonic solution (Chamberl...

Apolipoprotein E-Derived Peptides Ameliorate Clinical Disability and Inflammatory Infiltrates into the Spinal Cord in a Murine Model of Multiple Sclerosis

“…at ASPET Journals on May 12, 2018 jpet.aspetjournals.org mine whether this is due to enhanced penetration of the BBB, as has been reported for other PTD-drug conjugates (Rousselle et al, 2003). The exact mechanism underlying this difference is a matter of active investigation, and our unpublished data suggest that COG133 interferes with certain intracellular signal transduction pathways (N. Ohkubo, C. A. Colton, F.-Q.…”

Improved Brain Uptake and Pharmacological Activity Profile of Morphine-6-Glucuronide Using a Peptide Vector-Mediated Strategy

“…Our results confirm our previous reports that vectorization of drugs with SynB vectors results in an enhancement of brain uptake and pharmacological activity (Rousselle et al, , 2002(Rousselle et al, , 2003Blanc et al, 2004). In the present study, our rationale was to attach M6G to the SynB3 peptide vector to enhance its brain uptake.…”

“…Recently, we have shown that small peptide vectors can be used to enhance brain uptake of various drugs without opening the tight junctions (Rousselle et al, , 2002. The potential of this approach as an effective brain delivery system has been demonstrated for various drugs (Rousselle et al, , 2002(Rousselle et al, , 2003Blanc et al, 2004).…”

CNS Delivery Via Adsorptive Transcytosis

“…Moreover, the K D values measured for the Syn-B transport reside in the micromolar range, and compare well with the values observed for molecules described as being taken up by adsorptive-mediated endocytosis. Similar characteristics of transport were demonstrated for the cell uptake of Syn-B vectors conjugated to a fluorophore (27) or various drugs (34,69,70).…”

“…Indeed, many cargo models used to demonstrate the ability of CPPs to efficiently translocate small or large molecules into cellsfor example fluorescent probes or the GFP or beta-galactosidase tags-have no therapeutic value whatsoever. However, there are several examples where CPPs have been used successfully to deliver therapeutic molecules through the BBB and into the brain, but as it stands today, most examples are limited to low molecular weight drugs and small peptide drugs (34,69,70,76). The first benchmark study of the ability of CPPs to deliver proteins across the BBB is probably that of Schwarze and Coll.…”