Increased Nociceptive Responses in Streptozotocin-Induced Diabetic Rats and the Related Expression of Spinal NR2B Subunit of N-Methyl-D-Aspartate Receptors

BACKGROUND: This study investigated the role of NR2B in a modulated pain process in the painful diabetic neuropathy (PDN) rat using various pain stimuli. METHODS: Thirty-two Sprague-Dawley male rats were randomly allocated into four groups (n=8): control, diabetes mellitus (DM) rats and diabetic rats treated with ifenprodil at a lower dose (0.5 µg/day) (I 0.5) or higher dose (1.0 µg/day) (I 1.0). DM was induced by a single injection of streptozotocin at 60 mg/kg on day 0 of experimentation. Diabetic status was assessed on day 3 of the experimentation. The responses on both tactile and thermal stimuli were assessed on day 0 (baseline), day 14 (pre-intervention), and day 22 (post-intervention). Ifenprodil was given intrathecally for 7 days from day 15 until day 21. On day 23, 5% formalin was injected into the rats' hind paw and the nociceptive responses were recorded for 1 hour. The rats were sacrificed 72 hours post-formalin injection and an analysis of the spinal NR2B expression was performed. RESULTS: DM rats showed a significant reduction in pain threshold in response to the tactile and thermal stimuli and higher nociceptive response during the formalin test accompanied by the higher expression of phosphorylated spinal NR2B in both sides of the spinal cord. Ifenprodil treatment for both doses showed anti-allodynic and anti-nociceptive effects with lower expression of phosphorylated and total spinal NR2B. CONCLUSION: We suggest that the pain process in the streptozotocin-induced diabetic rat that has been modulated is associated with the higher phosphorylation of the spinal NR2B expression in the development of PDN, which is similar to other models of neuropathic rats.

The Potential of Centella asiatica (Linn.) Urban as an Anti-Microbial and Immunomodulator Agent: A Review

Centella asiatica (Linn.) Urban (Umbelliferae) which is also known as ‘pegaga’ is highly consumed and eaten raw as ‘ulam’ in Malaysia. C. asiatica is used in traditional medicines to treat various health conditions such as rheumatism, inflammation, syphilis, skin diseases and diarrhoea. Various reports exhibited that the crude extracts and isolated bioactive compounds of C. asiatica possessed a broad range of pharmacological activities such as anti-oxidant, anti-diabetic, anti-tumor, wound healing, anti-microbial, anti-inflammatory, immunomodulatory, hepatoprotective and memory enhancing properties. The pharmacological validation on anti-microbial and immunomodulatory of C. asiatica is very limited and several existence review papers related for this plant had not been focused for both activities. This review therefore attempts to combine the existing literature to offer immense scope for researchers engaged in validation of the traditional claims and bioactivities of this plant related with anti-microbial and immunomodulatory potential.

Role of toll-like receptor 4 in eliciting adaptive immune responses against recombinant BCG expressing the C-terminus of merozoite surface protein-1 of Plasmodium falciparum

Objective: To determine the role of toll-like receptor 4 (TLR-4) in eliciting cellular and humoral immune responses against recombinant Mycobacterium bovis bacille Calmette-Guérin (rBCG) expressing the C-terminus of merozoite surface protein-1 of Plasmodium falciparum. Methods: Six groups of mice (n=6 per group) were injected with phosphate buffered saline T80, BCG or rBCG intraperitoneally, in the presence or absence of a TLR-4 inhibitor; TAK-242. Enzyme-linked immunosorbent assay was carried out for serum total IgG, IgG1, IgG2a and IgG2b determination. Spleens were also harvested and splenocytes cultured for determination of intracellular cytokines; IL-4 and IFN-γ via enzyme-linked immunosorbent assay. Results: The production of total IgG, and the subclasses IgG1, IgG2a and IgG2b was significantly higher in rBCG-immunised mice than BCG and phosphate buffered saline immunised mice in the absence of TAK-242. A significant rise in total IgG occurred with more booster immunisations. The level of IgG2a was highest, followed by IgG2b, then IgG1. The production of both IL-4 and IFN-γ was also highest in the rBCG immunised groups. These significant rises were inhibited in the presence of TAK-242. Conclusions: We present evidence of the role of TLR-4 in the increased production of total IgG, IgG1, IgG2a and IgG2b, as well as IL-4 and IFN-γ in response to our rBCG construct.

Pam3CSK4 enhances adaptive immune responses to recombinant Mycobacterium bovis bacille Calmette-Guérin expressing Plasmodium falciparum C-terminus merozoite surface protein-1

Objective: To determine the effects of toll-like receptor 2 (TLR-2) agonist, Pam3CSK4, on cellular and humoral immune response against recombinant Mycobacterium bovis bacille Calmette-Guérin (rBCG) expressing the C-terminus of merozoite surface protein-1 of Plasmodium falciparum. Methods: Six groups of mice (n=6 per group) received intraperitoneal phosphate buffered saline T80 (PBS-T80), BCG or rBCG in the presence or absence of Pam3CSK4. Enzyme-linked immunosorbent assay was carried out to measure serum total IgG, IgG1, IgG2a, and IgG2b production. Spleens were also harvested and splenocytes were co-cultured with rBCG antigen for in vitro determination of IL-4 and IFN-γ via enzyme-linked immunosorbent assay. Results: The production of total IgG and the isotype IgG1, IgG2a and IgG2b was significantly higher in rBCG-immunised mice than in the BCG and PBS-T80-immunised mice, and Pam3CSK4 further enhanced their productions. A similar pattern was also observed in IFN-γ production. Moreover, there was no significant difference in IL-4 production in all groups either in the presence or absence of Pam3CSK4. Conclusions: We present evidence of the adjuvant effects of TLR-2 agonist in enhancing the production of total IgG, IgG1, IgG2a, IgG2b, as well as IFN-γ in response to rBCG. However, the presence or absence of Pam3CSK4 had no effect on IL-4 production.

Role of toll like-receptor 2 in inflammatory activity of macrophage infected with a recombinant BCG expressing the C-terminus of merozoite surface protein-1 of Plasmodium falciparum

Objective: To investigate the role of toll-like receptor 2 (TLR2) in inflammatory activity of macrophage infected with the recombinant Mycobacterium bovis bacillus Calmette-Guerin (rBCG). Methods: Mouse macrophage cell line J774A.1 was infected with Mycobacterium bovis bacillus Calmette-Guerin (BCG) and rBCG cultures for 48 h in the presence or absence of 10 μg/mL of TLR2 inhibitor. Untreated macrophages were used as a negative control while lipopolysaccharide-stimulated macrophages were used as a positive control. The ability of the macrophage to engulf the BCG and rBCG in the absence or presence of TLR2 inhibitor was assessed using a phagocytic assay, while the production of inflammatory cytokines and nitric oxide by the infected macrophages was evaluated using ELISA and Griess reagent method, while the expression of the inducible nitric oxide synthase was determined using Western blot analysis. Results: The results showed that blocking TLR2 function reduced the phagocytic activity, nitric oxide production and proinflammatory cytokine secretion such as TNF- α, IL-1 β and IL-12p40 as well as inducible nitric oxide synthase expression in the infected macrophages. These data showed the importance of TLR2 in the activation of macrophages following BCG and rBCG infections. Conclusions: Through exploring the immunological mechanism which underlies the protection conferred by the candidate vaccine, this study will improve our understanding of the vaccine candidate's mechanism to protect the host from malaria infection.

The Effects of Pre-emptive Administration of Ketamine and norBNI on Pain Behavior, c-Fos, and Prodynorphin Protein Expression in the Rat Spinal Cord after Formalin-induced Pain Is Modulated by the DREAM Protein

BACKGROUND: We investigated the effects of pre-emptive administration of ketamine and norBNI on pain behavior and the expression of DREAM, c-Fos, and prodynorphin proteins on the ipsilateral side of the rat spinal cord at 2 and 4 hours after formalin injection. METHODS: Eighty-four male Sprague Dawley rats were divided into 4 major groups consisting of control rats (C) (n = 12), rats given only formalin injections (F) (n = 24), and rats treated with pre-emptive administration of either ketamine (K+F) (n = 24) or norBNI (N+F) (n = 24). The non-control groups were further divided into subgroups consisting of rats that were sacrificed at 2 and 4 hours (n = 12 for each group) after formalin injection. Pain behavior was recorded for 1 hour. After 2 and 4 hours, the rats were sacrificed and the spinal cords (L4-L5 sections) were removed for immunohistochemistry and Western blot analysis. RESULTS: The pain behavior response was reduced in the K+F group compared to the other groups during the second phase of the formalin pain response. We detected an increase in the nuclear DREAM protein level in the K+F group at 2 and 4 hours and a transient decrease in the N+F group at 2 hours; however, it increased at 4 hours after injection. Fos-like immunoreactivity (FLI) and Prodynorphin-like immunoreactivity (PLI) neurons decreased in the K+F group but increased in the N+F group at 2 hours after injection. While FLI decreased, PLI increased in all groups at 4 hours after injection. CONCLUSIONS: We suggest that NMDA and kappa opioid receptors can modulate DREAM protein expression, which can affect pain behavior and protein transcriptional processes at 2 hours and bring about either harmful or protective effects at 4 hours after formalin injection.