Engineered endomorphin-2 gene: A novel therapy for improving morphine reinstatement in CPP model of rats by using deficient adenovirus as the vector.

Optimal therapeutics to deal with high relapse rates when discontinued is urgent for opioid dependence treatments. Endogenous endomorphin-2 (EM2) level in the central nervous system (CNS) down-regulates obviously after sustained morphine exposure, which suggested that to up-regulate the EM2 level could be a novel method for reinstatement. But the clinical applications of EM2 through conventional administration are limited owing to its short half-life. In our study, we engineered an EM2 gene to achieve the sustained release of EM-2 in CNS by utilizing a signal peptide of mouse growth factor for out-secreting EM2 and a deficient adenovirus as the vector. By intrathecally injecting engineering EM2 gene, a sustained increase of EM2 concentration in the cerebral spinal fluid (CSF) was observed along with a reduction of CPP scores. Also, the activation of astrocytes was suppressed in the hippocampus. In summary, this study provides evidence and reference for using intraspinal gene therapy with a combination of mouse growth factor and EM2 to treat morphine reinstatement.

Inducible Lentivirus-Mediated siRNA against TLR4 Reduces Nociception in a Rat Model of Bone Cancer Pain.

Although bone cancer pain is still not fully understood by scientists and clinicians alike, studies suggest that toll like receptor 4 (TLR4) plays an important role in the initiation and/or maintenance of pathological pain state in bone cancer pain. A promising treatment for bone cancer pain is the downregulation of TLR4 by RNA interference; however, naked siRNA (small interference RNA) is not effective in long-term treatments. In order to concoct a viable prolonged treatment for bone cancer pain, an inducible lentivirus LvOn-siTLR4 (tetracycline inducible lentivirus carrying siRNA targeting TLR4) was prepared and the antinociception effects were observed in bone cancer pain rats induced by Walker 256 cells injection in left leg. Results showed that LvOn-siTLR4 intrathecal injection with doxycycline (Dox) oral administration effectively reduced the nociception induced by Walker 256 cells while inhibiting the mRNA and protein expression of TLR4. Proinflammatory cytokines as TNF-α and IL-1ß in spinal cord were also decreased. These findings suggest that TLR4 could be a target for bone cancer pain treatment and tetracycline inducible lentivirus LvOn-siTLR4 represents a new potential option for long-term treatment of bone cancer pain.

[Synthesis and characterization of N-octyl-N-arginine chitosan--a chitosan derivant with a mimetic structure of cell-penetrating peptides].

A novel chitosan derivant, N-octyl-N-arginine chitosan (OACS) with a mimetic structure of cell-penetrating peptides was synthesized by introducing hydrophilic arginine groups and hydrophobic octyl groups to the amino-group on chitosan's side chain. Structure of the obtained polymer was characterized by FT-IR and 1H NMR. The substitution degree of octyl and arginine groups was calculated through element analysis and spectrophotometric method, separately. The critical micelle concentration of OACS was 0.12 - 0.27 mgmL(-1) tested by fluorescence spectrometry. The solubility test showed OACS could easily dissolve in pH 1 - 12 solutions and self-assemble to form a micelle solution with light blue opalescence. The OACS micelles have a mean size of 158.4 - 224.6 nm, polydisperse index of 0.038 - 0.309 and a zeta potential of +19.16 - +30.80 mV determined by malvern zetasizer. AFM images confirmed free OACS micelle has a regular sphere form with a uniform particle size. MTT test confirmed that OACS was safe in 50 - 1 000 micromol-L(-1). The result of HepG2 cell experiment showed that the cell internalization of OACS micelles enhanced with increased substitution degree of arginine by 40 folds compared to chitosan. Thus, OACS micelles were a promising nano vehicle with permeation enhancement and drug carrier capability.

Dezocine inhibits cell proliferation, migration, and invasion by targeting CRABP2 in ovarian cancer.

Previous studies have shown that some anesthesia drugs can inhibit tumor growth and metastasis. As a clinical anesthetic drug, dezocine has been reported to play an important role in immune function. However, the effects of dezocine on ovarian cancer cell growth and metastasis are not fully understood. In this study, we found that dezocine dose-dependently inhibited the viability of ES-2 and SKOV3 cells. Dezocine suppressed the migration and invasion abilities of ovarian cancer cells, and promoted apoptosis. Moreover, the Akt/mTOR signaling pathway was also inhibited by dezocine. Furthermore, mechanism study showed that dezocine could significantly inhibit the expression of CRABP2, and CRABP2 overexpression reversed the inhibitory effects of dezocine on ovarian cancer cell proliferation and migration. In conclusion, dezocine has significant anti-tumor effects on the growth and metastatic potential of ovarian cancer cells, and CRABP2 functions as a downstream effector of dezocine.

Topical anesthetic and pain relief using penetration enhancer and transcriptional transactivator peptide multi-decorated nanostructured lipid carriers.

Many strategies have been developed to overcome the stratum corneum (SC) barrier, including functionalized nanostructures. Chemical penetration enhancers (CPEs) and cell-penetrating peptides (CPP) were applied to decorate nanostructured lipid carriers (NLC) for topical anesthetic and pain relief. A novel pyrenebutyrate (PB-PEG-DSPE) compound was synthesized by the amide action of the carboxylic acid group of PB with the amido groups of DSPE-PEG. PB-PEG-DSPE has a hydrophobic group, hydrophilic group, and lipid group. The lipid group can be inserted into NLC to form PB functional NLC. In order to improve the penetrability, TAT and PB multi-decorated NLC were designed for the delivery of lidocaine hydrochloride (LID) (TAT/PB LID NLC). The therapeutic effects of NLC in terms of in vitro skin penetration and in vivo in animal models were further studied. The size of TAT/PB LID NLC tested by DLS was 153.6 ± 4.3 nm. However, the size of undecorated LID NLC was 115.3 ± 3.6 nm. The PDI values of NLC vary from 0.13 ± 0.01 to 0.16 ± 0.03. Zeta potentials of NLC were negative, between -20.7 and -29.3 mV. TAT/PB LID NLC (851.2 ± 25.3 µg/cm2) showed remarkably better percutaneous penetration ability than PB LID NLC (610.7 ± 22.1 µg/cm2), TAT LID NLC (551.9 ± 21.8 µg/cm2) (p < .05) and non-modified LID NLC (428.2 ± 21.4 µg/cm2). TAT/PB LID NLC exhibited the most prominent anesthetic effect than single ligand decorated or undecorated LID NLC in vivo. The resulting TAT/PB LID NLC exhibited good skin penetration and anesthetic efficiency, which could be applied as a promising anesthesia system.

Lentiviral­mediated inducible silencing of TLR4 attenuates neuropathic pain in a rat model of chronic constriction injury.

An increasing body of evidence has indicated that spinal microglial Toll­like receptor 4 (TLR4) may serve a significant role in the development and maintenance of neuropathic pain (NP). In the present study, experiments were conducted to evaluate the contribution of a tetracycline inducible lentiviral­mediated delivery system for the expression of TLR4 small interfering (si)RNA to NP in rats with chronic constriction injury (CCI). Behavioral tests, including paw withdrawal latency and paw withdrawal threshold, and biochemical analysis of the spinal cord, including western blotting, reverse transcription­quantitative polymerase chain reaction and ELISA, were conducted following CCI to the sciatic nerve. Intrathecal administration of LvOn­si­TLR4 with doxycycline (Dox) attenuated allodynia and hyperalgesia. Biochemical analysis revealed that the mRNA and proteins levels of TLR4 were unregulated following CCI to the sciatic nerve, which was then blocked by intrathecal administration of LvOn­siTLR4 with Dox. The LvOn­siTLR4 was also demonstrated to have no effect on TLR4 or the pain response without Dox, which indicated that the expression of siRNA was Dox­inducible in the lentivirus delivery system. In conclusion, TLR4 may serve a significant role in neuropathy and the results of the present study provide an inducible lentivirus­mediated siRNA against TLR4 that may serve as a potential novel strategy to be applied in gene therapy for NP in the future.

An Engineered Endomorphin-2 Gene for Morphine Withdrawal Syndrome.

An optimal therapeutics to manage opioid withdrawal syndrome is desired for opioid addiction treatment. Down-regulation of endogenous endomorphin-2 (EM2) level in the central nervous system after continuous morphine exposure was observed, which suggested that increase of EM2 could be an alternative novel method for opioid dependence. As a short peptide, the short half-life of EM2 limits its clinical usage through conventional administration. In the present study, we engineered an EM2 gene using a signal peptide of mouse growth factor for an out-secretory expression of EM2 and an adenovirus as a vector, which ultimately sustained the release of EM-2. After administration of the adenovirus in central nervous system, a sustained increase of EM2 level in the cerebral spinal fluid (CSF) was observed along with a reduction of morphine withdrawal syndrome. These findings suggest that the engineered EM2 gene delivered to the central nervous system could be a novel therapeutics for withdrawal syndrome in opioid dependent subjects.

The Anti-Nociception Effect of Dezocine in a Rat Neuropathic Pain Model.

The treatment of neuropathic pain (NP) currently remains clinically challenging. In an attempt to identify novel targets of known opioids, we found that dezocine, a non-addictive opioid, inhibits norepinephrine and serotonin reuptake through their transporter proteins which open the potential for dezocine to manage NP. In the present study, the effect of dezocine on NP was observed in a rat model of chronic constriction injury (CCI). The paw withdrawal latency (PWL) and paw withdrawal threshold (PWT) were used to evaluate thermal hyperalgesia and mechanic allodynia for nociceptive response. PWL and PWT tests were performed at 11:00 AM starting from 1 day before CCI surgery and 1, 3, 7, 10 days after right sciatic nerve ligation in the presence or absence of daily intraperitoneal injection of dezocine. The results demonstrated that the CCI-induced thermal and mechanical pain hypersensitivity was attenuated by dezocine significantly and persistently without sign of tolerance, indicating that dezocine could be an alternative medication for the treatment of NP. Clinical trial to confirm such discovery is warranted.

Lentivirus mediated siRNA against GluN2B subunit of NMDA receptor reduces nociception in a rat model of neuropathic pain.

Although neuropathic pain (NP) is still not fully understood by scientists and clinicians alike, studies suggest that N-methyl-D-aspartate (NMDA) receptors play an important role in the induction and maintenance of NP. A promising treatment for NP is through the downregulation of NMDA subunit GluN2B by RNA interference; however, naked siRNA (small interference RNA) is not effective in long-term treatments. In order to concoct a viable prolonged treatment for NP, Lv-siGluN2B (lentivirus carrying siRNA targeting GluN2B subunit) was prepared and the antinociception effects were observed in chronic constriction injury (CCI) rats in the present study. Results showed that Lv-siGluN2B was transduced into spinal cord cells after intrathecal injections and effectively reduced the nociception induced by sciatic nerve ligation while inhibiting the mRNA and protein expression of GluN2B. This antinociception effect lasted approximately 7 weeks. These findings suggest that GluN2B subunit could be a target for NP treatment and Lv-siGluN2B represents a new potential option for long-term treatment of NP.

Bilirubin modulates acetylcholine receptors in rat superior cervical ganglionic neurons in a bidirectional manner.

Autonomic dysfunction as a partial contributing factor to cardiovascular instability in jaundiced patients is often associated with increased serum bilirubin levels. Whether increased serum bilirubin levels could directly inhibit sympathetic ganglion transmission by blocking neuronal nicotinic acetylcholine receptors (nAChRs) remains to be elucidated. Conventional patch-clamp recordings were used to study the effect of bilirubin on nAChRs currents from enzymatically dissociated rat superior cervical ganglia (SCG) neurons. The results showed that low concnetrations (0.5 and 2 µM) of bilirubin enhanced the peak ACh-evoked currents, while high concentrations (3 to 5.5 µM) of bilirubin suppressed the currents with an IC50 of 4 ± 0.5 µM. In addition, bilirubin decreased the extent of desensitization of nAChRs in a concentration-dependent manner. This inhibitory effect of bilirubin on nAChRs channel currents was non-competitive and voltage independent. Bilirubin partly improved the inhibitory effect of forskolin on ACh-induced currents without affecting the action of H-89. These data suggest that the dual effects of enhancement and suppression of bilirubin on nAChR function may be ascribed to the action mechanism of positive allosteric modulation and direct blockade. Thus, suppression of sympathetic ganglionic transmission through postganglionic nAChRs inhibition may partially contribute to the adverse cardiovascular effects in jaundiced patients.

N-octyl-N-Arginine chitosan micelles as an oral delivery system of insulin.

N-octyl-N-Arginine chitosan (OACS) was synthesized in an attempt to combine the permeation enhancing effects of arginine-rich peptides and the drug loading capacity of the amphipathic polymers for insulin oral delivery. OACS self-assembled micelles of insulin were prepared by the conventional stirring technique, which were characterized by Dynamic light scattering, transmission electron microscopy and differential scanning calorimetry. Molecular docking by Discovery studio software confirmed that the interactions between OACS and insulin were mostly electrostatic in nature. In vitro, the result of the degradation experiment by enzyme showed that the OACS has a relative protective effect for insulin from proteolyses. Compared to the insulin solution, OACS micelles increased the Caco-2 cell's internalization by up to 22.3 folds. In vivo, the pharmacological activity PA% of series OACS-insulin micelles ranged from 7.7%-16.8%. Meanwhile by increasing arginine degree of the substitution both the uptake in Caco-2 cells and the hypoglycemic effect in diabetic rats were enhanced. Therefore, it is concluded that using arginine polymeric micelles for the enhancement of oral insulin delivery is a promising approach for the oral peptide delivery.