Analgesic synergism of gabapentin and carbamazepine in rat model of diabetic neuropathic pain

Purpose: To evaluate synergy in the analgesic effects of a combination therapy of carbamazepine (CBZ) and gabapentin (GBP) in diabetic neuropathic pain. Methods: Neuropathic pain was produced in rats by a single intraperitoneal injection of streptozotocin (STZ) at 60 mg/kg. CBZ, GBP, and their combination were orally administered at varying doses (GBP 30 - 180 mg/kg; CBZ 20 - 40 mg/kg) comparable to their therapeutic doses in humans. Nociceptive responses in the diabetic rats were assessed using hot plate test. Results: Hot plate latency significantly increased with oral administration of GBP at a dose of 180 mg/kg when compared with control group (p < 0.05), while at a dose of 90 mg/kg, the increase was not significant. Oral administration of CBZ at doses of 20 and 40 mg/kg did not produce any significant impact on hot plate latency. However, a combination of GBP at 90 mg/kg and CBZ at 20 mg/kg produced significant increase in latency, compared with control group and other groups (p < 0.05), except the group that received 180 mg/kg GBP. The combination of low dose GBP 30 mg/kg and carbamazepine 30 mg/kg had no significant effect on latency (p > 0.05). Conclusion: The results obtained in this study provide useful information on the combination therapy of GBP and CBZ, which may be applied in the treatment of pain in diabetic neuropathy.

Protective effect of Rhizoma drynariae extract on osteoporosis in ovariectomized rat model

Purpose: To investigate the therapeutic effect of Rhizoma drynariae extract (RDE) on ovariectomyinduced osteoporosis in rats. Methods: Female Sprague-Dawley rats were randomly assigned to a sham-operated group (control) and five ovariectomy (OVX) subgroups: OVX with vehicle (OVX), OVX with 17ß-estradiol (E2, 25 μg/kg/day), and OVX with RDE doses (40, 80, and 160 mg/kg/day). Daily oral administration of E2 or RDE started 4 weeks after OVX and lasted for 16 weeks. The bone mineral density (BMD) of the L4 vertebrae and right femurs was estimated. The length of each femur was measured with a micrometer gauge, and the center of the diaphysis determined. Three representatives L4 vertebrae were selected to evaluate the trabecular microarchitecture. Serum alkaline phosphatase (ALP), urinary calcium (U-Ca), urinary phosphorus (U-P), urinary creatinine (Cr) and osteocalcin (OC) levels were measured. Results: The study showed that high-dose of RDE significantly inhibited the bone mineral density (BMD) reduction of L4 vertebrae (0.20 ± 0.02 g/cm3, p < 0.05) and femurs (0.18 ± 0.02 g/cm3, p < 0.05) caused by OVX and prevented the deterioration of trabecular microarchitecture (p < 0.05), which were accompanied by a significant decrease in skeletal remodeling (p < 0.05) as evidenced by the lower levels of bone turnover markers. High-dose of RDE improved morphometric parameters, namely, Tb-N (3.8 ± 0.2 mm, p < 0.05), Tb-Th (0.083 ± 0.011 mm, p < 0.05) and Tb-Sp (0.19 ± 0.01 mm, p < 0.05) in L4 vertebrae significantly. The present study indicates that the administration of RDE at higher doses over a 16-week period can prevent OVX-induced osteoporosis in rats without hyperplastic effects on the uterus. Conclusion: Thus, RDE is a potential natural alternative for postmenopausal osteoporosis treatment in elderly women.

Effect of Lycii fructus polysaccharides on ovulation failure in rats

Purpose: To investigate the effect of Lycii fructus polysaccharides (LFPS) on ovulation failure. Methods: A rat model of ovulation failure was established by intragastric administration of hydroxyurea (300 mg/kg). Rats with ovulation failure then received LFPS via oral administration at doses of 100, 200, or 400 mg/kg. The body, uterus and ovary of each rat were weighed using electronic scales. The hypothalamic-pituitary-ovarian (HPO) axis hormones, including estradiol (E2) level, follicle-stimulating hormone (FSH) activity, and luteinizing hormone (LH) activity in the serum of each rat were determined by enzyme-linked immunosorbent assay (ELISA). The levels of pro-apoptotic proteins (Fas, FasL, FADD, c-caspase-8, c-caspase-10, c-caspase-3, c-caspase-6, and c-caspase-7) in the ovarian tissue of each rat were detected by western blot. Results: Hydroxyurea reduced significantly (p < 0.01) uterus and ovary indices (uterus or ovary weight/body weight) (0.119 and 0.026 %), E2 level (3.42 pmol/L), and FSH and LH activities (2.28 and 2.76 U/L), compared with those in the normal group (0.169 and 0.039 %; 6.72 pmol/L; 2.76 and 3.75 U/L). Hydroxyurea increased significantly (p < 0.01) the levels of the above-mentioned pro-apoptotic proteins relative to those in the normal group. LFPS (100, 200, or 400 mg/kg) reversed significantly (p < 0.05 or 0.01) the effect of hydroxyurea on all of the above indices. Conclusion: LFPS exhibits a protective effect on hydroxyurea-induced ovulation failure by regulating the HPO axis hormones and death receptor-mediated apoptotic pathway.

Effect of Arisaema erubescens (Wall) Schott rhizome extract on rheumatoid arthritis

Purpose: To investigate the anti-arthritic activity of the water extract of Rhizoma Arisaematis (WERA) using a collagen II -induced arthritis (CIA) rat model. Methods: CIA was induced in male Sprague-Dawley rats by intradermal injection of bovine collagen II in Complete Freund’s Adjuvant. The rats were treated with daily oral doses of WERA (100, 200, and 400 mg/kg) for 21 consecutive days. Methotrexate (MTX, 3 mg/kg), used as a positive control, was administered orally 2 times/week for 3 weeks. The severity of arthritis was evaluated using indices of paw swelling, arthritic score, body weight, thymus index, and spleen index. In addition, the serum levels of IL-1β, IL-6, IL-10, and TNF-α were measured. Results: All doses of WERA significantly inhibited paw edema (p < 0.01), decreased arthritis scores (p < 0.01) and spleen index (p < 0.05), and alleviated the weight loss associated with CIA in rats. Furthermore, TNF-α, IL-1β, and IL-6 serum levels were significantly decreased (p < 0.05) by all doses of WERA. By contrast, IL-10 serum levels were markedly increased (p < 0.05). Conclusion: WERA exerts therapeutic effects in CIA in rats by decreasing the serum levels of TNF-α, IL-1β, IL-6 and IL-10, suggesting WERA may be an effective candidate drug for treating human rheumatoid arthritis.

Cardioprotective effects of Dan-Yang-Fu-Xin decoction on chronic heart failure in rats

Purpose: To evaluate the cardioprotective effects and possible mechanisms of Dan-Yang-Fu-Xin decoction (DYFX) in a rat chronic heart failure (CHF). Methods: A CHF rat model induced by ligation of the left anterior descending coronary artery was used to investigate the cardioprotective effects of DYFX. After intragastric administration for 8 weeks, several functional cardiac indices, including fractional shortening (FS), ejection fraction (EF), heart rate (HR) and cardiac output (CO) were assessed by ultrasound examination. Subsequently, inflammatory markers, viz, interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α), myocardial enzymes, namely, lactate dehydrogenase (LDH) and creatine kinase (CK), were also assessed by enzyme-linked immunosorbent assay (ELISA). Results: Intragastric administration of DYFX (200, 400 and 600 mg/kg) significantly reversed the decrease in body weight and increase in cardiac weight (p < 0.05) induced by CHF. Treatment with DYFX also significantly reversed EF, FS, HR, and CO changes in CHF rats. In addition, DYFX inhibited the two inflammatory cytokines (TNF-α and IL-6) and myocardial enzymes (CK and LDH), suggesting that these effects may include the mechanisms of cardioprotectiion involved in attenuation of CHF. Conclusion: DYFX possesses cardioprotective effects involving CHF. The protective mechanisms may include the suppression of expression of inflammatory mediators and myocardial enzymes.

In situ epicatechin-loaded hydrogel implants for local drug delivery to spinal column for effective management of post-traumatic spinal injuries

Purpose: To prepare hydrogels loaded with epicatechin, a strong antioxidant, anti-inflammatory, and neuroprotective tea flavonoid, and characterise them in situ as a vehicle for prolonged and safer drug delivery in patients with post-traumatic spinal cord injury. Methods: Five in situ gel formulations were prepared using chitosan and evaluated in terms of their visual appearance, clarity, pH, viscosity, and in vitro drug release. In vivo anti-inflammatory activity was determined and compared with 2 % piroxicam gel as standard. Motor function activity in a rat model of spinal injury was examined comparatively with i.v. methylprednisolone as standard. Results: The N-methyl pyrrolidone solution (containing 1 % w/w epicatechin with 2 to 10 % w/w chitosan) of the in situ gel formulation had a uniform pH in the range of 4.01 ± 0.12 to 4.27 ± 0.02. High and uniform drug loading, ranging from 94.48 ± 1.28 to 98.08 ± 1.24 %, and good in vitro drug release (79.48 ± 2.84 to 96.48 ± 1.02 % after 7 days) were achieved. The in situ gel prepared from 1 % epicatechin and 2 % chitosan (E5) showed the greatest in vivo anti-inflammatory activity (60.58 % inhibition of paw oedema in standard carrageenan-induced hind rat paw oedema model, compared with 48.08 % for the standard). The gels showed significant therapeutic effectiveness against post-traumainduced spinal injury in rats. E5 elicited maximum motor activity (horizontal bar test) in the spinal injury rat model; the rats that received E5 treatment produced an activity score of 3.62 ± 0.02 at the end of 7 days, compared with 5.0 ± 0.20 following treatment with the standard. Conclusion: In situ epicatechin-loaded gel exhibits significant neuroprotective and anti-inflammatory effects, and therefore can potentially be used for prolonged and safe drug delivery in patients with traumatic spinal cord injury.

Polymeric implant of methylprednisolone for spinal injury: preparation and characterization

Purpose: To improve the effectiveness and reduce the systemic side effects of methylprednisolone in traumatic spinal injuries, its polymeric implants were prepared using chitosan and sodium alginate as the biocompatible polymers. Methods: Implants of methylprednisolone sodium succinate (MPSS) were prepared by molding the drug-loaded polymeric mass obtained after ionotropic gelation method. The prepared implants were evaluated for drug loading, in vitro drug release and in vivo performance in traumatic spinal-injury rat model with paraplegia. Results: All the implant formulations were light pale solid matrix with smooth texture. Implants showed 86.56 ± 2.07 % drug loading. Drug release was 89.29 ± 1.25 % at the end of 7 days. Motor function was evaluated in traumatic spinal injury-induced rats in terms of its movement on the horizontal bar. At the end of 7 days, the test group showed the activity score (4.75 ± 0.02) slightly higher than that of standard (4.62 ± 0.25), but the difference was not statistically different (p > 0.05). Conclusion: MPSS-loaded implants produces good recovery in traumatic spinal-injury rats.

Immunomodulatory activity of methanol extract of Adansonia digitata L

Purpose: To evaluate the immune-modulatory activities of various plant parts Adansonia digitata L. using delayed-type hypersensitivity rat model. Methods: Defatted leaf, root bark and fruit pulp of A. digitata were extracted with methanol. Immunomodulatory activity of the methanol extracts (250 and 500 mg/kg) were evaluated in sheep RBC (SRBC)-induced delayed-type hypersensitivity model, cell mediated immune re-sponse and phagocytic activity using carbon clearance test. Results: The extracts exhibited significant increase in delayed-type hypersensitivity reaction, indicating the ability of the extracts to stimulate T-cells. It also increased SRBC induced anti-body titer in immunesuppressed rats, and produced significant increase in phagocytic index by rapid removal of carbon particles from the blood stream. Conclusion: These results indicate that methanol extracts of the leaf, root bark and fruit pulp of A. digitata hold promise as immunemodulatory agents.