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.
Animals ; Diabetes Mellitus ; Diabetic Neuropathies ; Formaldehyde ; Humans ; Hyperalgesia ; Male ; N-Methylaspartate ; Pain Measurement ; Pain Threshold ; Phosphorylation ; Rats ; Rats, Sprague-Dawley ; Receptors, N-Methyl-D-Aspartate ; Spinal Cord ; Streptozocin

OBJECTIVE: This study was done to determine whether Tualang honey could prevent the altered nociceptive behaviour, with its associated changes of oxidative stress markers and morphology of the spinal cord, among the offspring of prenatally stressed rats. METHODS: Pregnant rats were divided into three groups: control, stress, and stress treated with Tualang honey. The stress and stress treated with Tualang honey groups were subjected to restraint stress from day 11 of pregnancy until delivery. Ten week old male offspring (n = 9 from each group) were given formalin injection and their nociceptive behaviours were recorded. After 2 h, the rats were sacrificed, and their spinal cords were removed to assess oxidative stress activity and morphology. Nociceptive behaviour was analysed using repeated measures analysis of variance (ANOVA), while the levels of oxidative stress parameters and number of Nissl-stained neurons were analysed using a one-way ANOVA. RESULTS: This study demonstrated that prenatal stress was associated with increased nociceptive behaviour, changes in the oxidative stress parameters and morphology of the spinal cord of offspring exposed to prenatal stress; administration of Tualang honey reduced the alteration of these parameters. CONCLUSION This study provides a preliminary understanding of the beneficial effects of Tualang honey against the changes in oxidative stress and neuronal damage in the spinal cord of the offspring of prenatally stressed rats.

Introduction: Increased nociceptive responses were shown in the offspring of prenatally stressed rats. Reports have demonstrated the anti-nociceptive effects of Tualang honey in the rat offspring. The present study was done to determine whether the modulation of nociceptive behaviour by Tualang honey was mediated by modulating changes in the histology, oxidative stress parameters and N-methyl-D-aspartate (NMDA) receptors in the thalamus of the rat offspring. Methods: Eighteen Sprague Dawley pregnant rats were randomly assigned to control (C), stress (S) and stress-treated with Tualang honey (SH) groups. Stress was given in a form of restraint stress.Tualang honey was given to SH group from first day of pregnancy until delivery. Thirty-three adult male offspring were subjected to formalin test before they were sacrificed. Nociceptive behaviour score, number of neurons, level of oxidative stress parameters and NMDA receptors in the thalamus were analysed by using one-way ANOVA. Results: The study demonstrated a significant decrease in mean nociceptive behaviour score (p<0.05) with lower malondialdehyde (MDA, p<0.05) and higher superoxide dismutase SOD and catalase levels in the thalamus of SH group compared to S group (p<0.05). There was also increased Nissl positive neurons in the thalamus of SH group compared to S group. There was no significant difference in NMDA receptor level between S and SH groups. Conclusion: The modulation of nociceptive responses in the prenatally stressed rat offspring by Tualang honey was associated with improvement in oxidative stress parameters and histology of the thalamus in the rat offspring exposed to prenatal stress.

Introduction: Age-related macular degeneration (ARMD) is an ocular degenerative disorder that associated with impairment of central vision. Oxidative stress plays an important role in the pathogenesis of ARMD. The aim of this study was to determine the level of antioxidant enzymes (catalase and glutathione peroxidase) in tears among Malay ARMD patients. Methods: A cross sectional study was conducted between September 2015 and November 2017 among Malay ARMD patients. Schirmer paper was used to collect the tear samples. The level of catalase and glutathione peroxidase level in tears was evaluated using commercially available oxidative stress marker kits. Results: A total of 136 Malay ARMD patients were recruited into the study with 68 controls. Mean tear catalase and glutathione peroxidase levels were significantly lower in ARMD patients (1348.97 SD 109.11 µM and 453.87 SD 41.96 U/L respectively) as compared to the control group (1453.38 SD 38.87 µM and 502.28 SD 34.29 U/L respectively) (P<0.001 and P<0.001 respectively). Late ARMD has lower mean of catalase level in tears as compared to early ARMD (P=0.044). Based on subtypes of neovascular late ARMD, neovascular ARMD has lower mean catalase level in tears compared to idiopathic polypoidal choroidal vasculopathy (IPCV) (P=0.031). Conclusion: This study showed that antioxidant enzyme might play an important factor in the pathogenesis of ARMD.