Discovery, Optimization, and Biological Evaluation of Sulfonamidoacetamides as an Inducer of Axon Regeneration.

Axon regeneration after injury in the central nervous system is hampered in part because if an age-dependent decline in the intrinsic axon growth potential, and one of the strategies to stimulate axon growth in injured neurons involves pharmacological manipulation of implicated signaling pathways. Here we report phenotypic cell-based screen of chemical libraries and structure-activity-guided optimization that resulted in the identification of compound 7p which promotes neurite outgrowth of cultured primary neurons derived from the hippocampus, cerebral cortex, and retina. In an animal model of optic nerve injury, compound 7p was shown to induce growth of GAP-43 positive axons, indicating that the in vitro neurite outgrowth activity of compound 7p translates into stimulation of axon regeneration in vivo. Further optimization of compound 7p and elucidation of the mechanisms by which it elicits axon regeneration in vivo will provide a rational basis for future efforts to enhance treatment strategies.

Disrupted MEK/ERK signaling in the medial orbital cortex and dorsal endopiriform nuclei of the prefrontal cortex in a chronic restraint stress mouse model of depression.

Depression is one of the most prevalent mental illnesses, and causes a constant feeling of sadness and lose of interest, which often leads to suicide. Evidence suggests that depression is associated with aberrant MEK/ERK signaling. However, studies on MEK/ERK signaling in depression have only been done in a few brain regions, such as the hippocampus and mesolimbic reward pathways. Recent studies also implicate the involvement of the prefrontal cortex in depression. Thus, we examined the changes in MEK/ERK signaling in subregions of the prefrontal cortex of C57BL/6 mice by immunohistochemistry using phospho-MEK1/2 (Ser 217/221) and ERK1/2 (Thr202/Tyr204) antibodies. Mice were subjected to 21 consecutive days of restraint stress (for 2h daily), and depression-like behavior was evaluated using a sociability test and tail suspension test. The antidepressant, imipramine (20mg/kg) was injected intraperitoneally 30min before restraint stress exposure. Chronic/repeated restraint stress produced depressive-like behavior, such as increased social avoidance in the social interaction test, and enhanced immobility time in the tail suspension test. This depressive behavior was ameliorated by imipramine. The behavioral changes well corresponded to a decrease in MEK/ERK immunoreactivity in the medial orbital (MO) cortex and dorsal endopiriform nuclei (DEn), which was averted by imipramine, but not in cingulate, prelimbic, infralimbic, and motor cortex. These results suggest that MEK/ERK signaling is disrupted in the DEn and MO subregions of the prefrontal cortex in the depressive phenotype, and that blocking a decrease in activated MEK/ERK is inherent to the antidepressant imipramine response.

Insulin-loaded microcapsules for in vivo delivery.

Microencapsulation of insulin has been difficult, due to the high sensitivity of insulin to the harsh conditions that can occur during the microencapsulation process. We have developed a method of preparing insulin-loaded microcapsules by using a monoaxial ultrasonic atomizer to form microdroplets of insulin in aqueous solution surrounded by poly(lactic-co-glycolic acid) (PLGA) solution. Administration of these insulin-loaded microcapsules to type 1 diabetic rats maintained plasma insulin concentrations for 30 days, due to the sustained insulin release properties of the microcapsules. In contrast, plasma insulin concentrations after subcutaneous injection of insulin solution reached near zero levels within 2 days. Insulin solution showed only an immediate pharmacological effect, with no reduction of glycemia after 3 days, whereas insulin-loaded microcapsules maintained blood glucose levels at 100-200 mg/dL for 55 days. Molecular imaging using fluorescein isothiocyanate (FITC)-insulin-loaded microcapsules showed in vivo sustained release of the FITC-insulin in microcapsules. Using insulin-loaded microcapsules, we observed inflammation only immediately after injection, indicating that the rats adapted to long-term insulin release. In conclusion, insulin-loaded microcapsules may reduce nonrepetitive insulin administration and show sustained pharmacological performance.

In vitro and in vivo release of albumin using a biodegradable MPEG-PCL diblock copolymer as an in situ gel-forming carrier.

An MPEG-PCL diblock copolymer was synthesized as an in situ gel carrier, and its phase transition behavior in aqueous solutions was examined. For comparison, aqueous solutions of Pluronic F-127, a widely used injectable gel-forming solution, were also studied. Both MPEG-PCL copolymer and Pluronic aqueous solutions were sols at room temperature. As the temperature was increased above room temperature, the diblock copolymer and Pluronic solutions underwent a sol-to-gel phase transition, which manifested as an increase in viscosity indicative of the formation of a gel. All of the copolymer solutions became gels at body temperature, although the gel viscosity increased with the increasing concentration of the MPEG-PCL diblock copolymer in the solution. In in vitro experiments, in which the gels were exposed to PBS, the MPEG-PCL gels maintained their structural integrity for more than 28 days, whereas the Pluronic gel disappeared within 2 days. The same results were observed when the polymer solutions were subcutaneously injected into rats. The MPEG-PCL gels maintained their structural integrity longer than 30 days, while the Pluronic gel could not be observed after 2 days. The ability of the gels as drug carriers was studied by measuring the release of fluorescein isothiocyanate-labeled bovine serum albumin (BSA-FITC) from MPEG-PCL diblock copolymer gels in vitro as well as in vivo. In vitro, BSA release was sustained above 20 days, with a greater release at lower diblock copolymer concentration; by contrast, Pluronic gels exhibited almost complete release of BSA-FITC within 1 day. When the BSA-FITC-loaded diblock copolymer and Pluronic solutions were subcutaneously injected into rats, they immediately transformed into a gel. In vivo, sustained release of BSA-FITC over 30 days was observed from the MPEG-PCL gel, whereas BSA-FITC release from the Pluronic gel ceased within 3 days. Collectively, the present findings show that MPEG-PCL diblock copolymer solutions are thermo-responsive and maintain their structural integrity under physiological conditions, indicating that they are suitable for use as injectable drug carriers.