Hot Plate Latency Research Articles

Anti-inflammatory and antinociceptive activities of glucagon-like peptides: evaluation of their actions on serotonergic, nitrergic, and opioidergic systems.

Glucagon-like peptide-1 (GLP-1) and glucagon-like peptide-2 (GLP-2) are gut derived hormones. GLP-1 and GLP-2 were shown to have pleiotropic effects in intestinal and pancreatic diseases. We aimed to investigate the activities of GLP-1 and GLP-2 on nociception and inflammation in mice, involving their actions on serotonergic, nitrergic, and opioidergic systems. Antinociceptive and anti-inflammatory activities of intraperitoneally injected GLPs were evaluated in hotplate latency test, formalin-induced behavioral, and paw edema tests. Ondansetron, a selective 5-HT3 receptor antagonist; L-NAME, a NOS inhibitor; and naloxone, an opioid antagonist were injected to determine the mechanisms of antinociception and anti-inflammation. We also measured blood glucose levels and performed rotarod test in order to evaluate whether the hypoglycemic effect of GLP compounds or alterations in locomotor activity may affect the latency in hotplate test and activity in formalin test. GLP-1 (0.2mg/kg) and GLP-2 (0.05, 0.2mg/kg) significantly increased pain threshold. GLP-1 (0.2mg/kg) and GLP-2 (0.05, 0.1, 0.2mg/kg) significantly decreased formalin-induced licking and shaking behaviors. GLP-1 or GLP-2 showed no significant inhibitory action on formalin-induced swelling in paws of mice. Antinociceptive actions of GLP-1 and GLP-2 were significantly decreased with ondansetron and naloxone, and paw shaking behavior significantly increased with naloxone. GLP-1 and GLP-2 did not impair rotarod performance, and did not cause a significant hypoglycemic effect in our normoglycemic mice after rotarod test. These finding indicated that the antinociceptive and anti-inflammatory effect of GLP-1 was related to opioidergic system. Antinociceptive effect of GLP-2 was partially related to 5-HT3 serotonergic or opioidergic system in hotplate test. However, the anti-inflammatory effect of GLP-2 was not directly related to 5-HT3, NO or opioids.

NOP-Related Mechanisms in Pain and Analgesia.

Since the discovery of the NOP receptor and N/OFQ as the endogenous ligand, evidence has appeared demonstrating the involvement of this receptor system in pain. This was not surprising for members of the opioid receptor and peptide families, particularly since both the receptor and N/OFQ are highly expressed in brain regions involved in pain, spinal cord, and dorsal root ganglia. What has been surprising is the complicated picture that has emerged from 25years of research. The original finding that N/OFQ decreased tail flick and hotplate latency, when administered i.c.v., led to the hypothesis that NOP receptor antagonists could have analgesic activity without abuse liability. However, as data accumulated, it became clear that not only the potency but the activity per se was different when N/OFQ or small molecule NOP agonists were administered in the brain versus the spinal cord and it also depended upon the pain assay used. When administered systemically, NOP receptor agonists are generally ineffective in attenuating heat pain but are antinociceptive in an acute inflammatory pain model. Most antagonists administered systemically have no antinociceptive activity of their own, even though selective peptide NOP antagonists have potent antinociceptive activity when administered i.c.v. Chronic pain models provide different results as well, as small molecule NOP receptor agonists have potent anti-allodynic and anti-hyperalgesic activity after systemic administration. A considerable number of electrophysiological and anatomical experiments, in particular with NOP-eGFP mice, have been conducted in an attempt to explain the complicated profile resulting from NOP receptor modulation, to examine receptor plasticity, and to elucidate mechanisms by which selective NOP agonists, bifunctional NOP/mu agonists, or NOP receptor antagonists modulate acute and chronic pain.

The establishment of a mouse model of deep endometriosis.

Is it possible to establish a mouse model of deep endometriosis (DE)? A mouse DE model that is macroscopically and microscopically similar to nodular lesions in humans can be constructed in as short as 3 weeks by intraperitoneal injection of uterine fragments along with the infusion of substance P (SP) and/or calcitonin gene-related peptide (CGRP). Although a baboon DE model was reported 5 years ago, its prohibitive cost and demand for facilities and expertise associated with the use of non-human primates put its use out of reach for most laboratories. A total of 48 female Balb/C mice were used for this study. Among them, 16 were randomly selected as donors that contributed uterine fragments, and the remaining 32 were recipient mice. The mice with induced endometriosis were followed up for 3-4 weeks. One day before the induction of endometriosis by intraperitoneal injection of uterine fragments, osmotic pumps were inserted into equal groups of recipient mice to infuse either sterile saline, SP, CGRP, or both SP and CGRP. The hotplate test was administrated to all mice at the baseline and before and after induction of endometriosis. Four (3 for the SP+CGRP group) weeks after induction, all mice were sacrificed. Their endometriotic lesions were excised, weighed and processed for histopathologic examination, and histochemistry, immunohistochemistry and immunofluorescence analyses of markers of proliferation, angiogenesis, epithelial-mesenchymal transition (EMT), fibroblast-to-myofibroblast transdifferentiation (FMT), smooth muscle metaplasia (SMM), mesothelial-mesenchymal transition (MMT) and endothelial-mesenchymal transition (EndoMT) were done. The extent of lesional fibrosis was evaluated by Masson trichrome staining. To further evaluate surrounding organ/tissue invasion, the peritoneal areas adhesive to the lesions were excised for immunohistochemical analysis. Endometriotic lesions in mice treated with SP and/or CGRP satisfied all requirements for DE, i.e. presence of endometrial epithelial and stromal cells, abundance of fibromuscular content, and encapsulation in surrounding tissues or organs. The lesion weight in the CGRP, SP and SP+CGRP groups was 1.62, 2.14 and 2.18-fold, respectively, heavier than that of control group. Concomitantly, the SP, CGRP and SP+CGRP groups had significantly shorter hotplate latency than that of control group. Lesions in mice treated with SP and/or CGRP, especially with SP+CGRP, exhibited characteristics consistent with EMT, FMT, SMM and extensive fibrosis, along with signs of MMT and EndoMT. Lesional invasion into surrounding tissues/organs was found to be 25.0, 75.0 and 87.5% in mice treated with CGRP, SP and SP+CGRP, but none in control mice. N/A. This study is limited by the use of histologic and immunohistochemistry analyses only and lacks molecular data. The establishment of a mouse DE model supports the idea that endometriotic lesions are wounds undergoing repeated tissue injury and repair and underscores the importance of microenvironments in shaping the lesions' destiny. In addition, signs consistent with MMT and EndoMT indicate that there may be more culpable factors that still remain unidentified and should be pursued in the future. Moreover, the close correlation between the extent of lesional fibrosis and markers of EMT, MMT, EndoMT, FMT and SMM as shown here should facilitate our understanding of the molecular mechanisms underlying the DE pathophysiology. Since this DE model is based on a biologically plausible and evidence-backed theory, it should shed much needed insight into the molecular mechanisms underlying the pathophysiology of DE. This research was supported by Grants 81471434 (S.W.G.), 81530040 (S.W.G.), 81771553 (S.W.G.), 81671436 (X.S.L.) and 81871144 (X.S.L.) from the National Natural Science Foundation of China. None of the authors has any conflict of interest to disclose.

Sciatic nerve regeneration with collagen type I hydrogel containing chitosan nanoparticle loaded by insulin

The current study was conducted to promote the extent of peripheral nerve regeneration using a collagen type I hydrogel containing chitosan nanoparticle loaded by insulin. The developed hydrogel increased the proliferation rate of Schwann cells as shown by tetrazolium salt-based assay. For functional analysis, the hydrogel was administrated in the sciatic nerve crush injury of Wistar rats. The results of the sciatic functional index, hot plate latency, compound muscle action potential amplitude and weight-loss percentage of the wet gastrocnemius muscle, indicated that the prepared hydrogel could be considered as a potential material for peripheral nerve regeneration.

The α2A -adrenoceptor subtype plays a key role in the analgesic and sedative effects of xylazine.

Xylazine, the classical α2 -adrenoceptor (α2 -AR) agonist, is still used as an analgesic and sedative in veterinary medicine, despite its low potency and affinity for α2 -ARs. Previous pharmacological studies suggested that the α2A -AR subtype plays a role in mediating the clinical effects of xylazine; however, these studies were hampered by the poor subtype-selectivity of the antagonists used and a lack of knowledge of their bioavailability in vivo. Here, we attempted to elucidate the role of the α2A -AR subtype in mediating the clinical effects of xylazine by comparing the analgesic and sedative effects of this drug in wild-type mice with those in α2A -AR functional knockout mice using the hot-plate and open field tests, respectively. Hippocampal noradrenaline turnover in both mice was also measured to evaluate the contribution of α2A -AR subtype to the inhibitory effect of xylazine on presynaptic noradrenaline release. In wild-type mice, xylazine (10 or 30mg/kg) increased the hot-plate latency. Furthermore, xylazine (3 or 10mg/kg) inhibited the open field locomotor activity and decreased hippocampal noradrenaline turnover. By contrast, all of these effects were abolished in α2A -AR functional knockout mice. These results indicate that the α2A -AR subtype is mainly responsible for the clinical effects of xylazine.

Partially protective effect of telmisartan on slow healing wounds in diabetic rats: possible role of AGEs-RAGE axis

Accumulation of advanced glycation endproducts (AGEs) has been found in healthy aging persons and during elevated glucose concentrations. It has been implicated in microvascular and macrovascular damage and delayed wound healing associated with diabetes, presumably through vascular, neurological, or intermediary metabolic modifications.The aim of the present work is to examine the potentially protective effect of telmisartan against diabetes-induced peripheral neuropathy in rats. Diabetic rats (Streptozotocin, STZ 50 mg/kg) were treated with vehicle or telmisartan (5 mg/kg) for 8 weeks. Behavioural tests (footprint and hotplate) were performed every 2 weeks after starting treatment. After 4 weeks of treatment, a wound was induced in the right hindlimb of rats and the wound size was measured every 3 days. At the end of the study, animals were sacrificed, blood, serum and hindlimb tissue were separated and used for further analyses.STZ treated rats showed a decrease in body weight, insulin, adiponectine level and soluble form of receptor of advanced glycation (sRAGE) expression and an increase in glucose, glycated haemoglobin A1c (HbA1c), tumor necrosis factor-α (TNF-α), advanced glycation end products level (AGEs) and receptor of advanced glycation end products (RAGE) expression compared to control group. This was associated with impaired performance in behavior tests and delayed wound healing. Treatment with telmisartan resulted in significant increase in body weight, serum adiponectin, serum sRAGE level and decreased TNF-α, insulin level, serum AGEs and RAGE compared to diabetes. Telmisartan lead to improvement only in gait base and intrastep distance in footprint parameters, while didn't improve hot plate latency or delayed wound healing.In conclusion, telmisartan may partially improve the deleterious effects of diabetes as peripheral neuropathy through its anti-glycation and anti-inflammatory effects

Comparison of electroencephalographic changes in response to acute electrical and thermal stimuli with the tail flick and hot plate test in rats administered with opiorphin

BackgroundThe objective of this study was to compare the changes in the electroencephalogram (EEG) in response to noxious stimuli with tail flick and hot plate responses of rats administered opiorphin.MethodsFemale Sprague -Dawley rats (n = 8 per group) randomly received intravenous (IV) injection of morphine (1 mg/kg,) or opiorphin (2 mg/kg,) or saline (0.5 ml,) in each of the three testing methods (EEG, tail flick and hot plate). Each type of test (n = 24 per test) was conducted in different population of rats on separate occasions. The tail flick and hot plate latencies were recorded until 5 min after test drug administration to conscious rats. The EEG was recorded in anaesthetised rats subjected to noxious thermal and electrical stimuli after test drug administration. At the end of 5 min in each of the testing methods rats were administered naloxone subcutaneously (SC) (1 mg/kg) and the test procedure was repeated.ResultsThere was no significant increase in the median frequency and spectral edge frequency (F50 & F95) of EEG, indicators of nociception, of morphine and opiorphin groups after noxious stimulation. Noxious stimuli caused a significant increase in both F50 and F95 of the saline group. An injection of naloxone significantly increased the F50, thus blocking the action of both opiorphin and morphine. There was a significant increase in the tail flick latency after administration of opiorphin and morphine as compared to the baseline values. Rats of morphine group spent significantly longer on the hot plate when compared to those of the opiorphin and saline groups. There was no significant difference in the hot plate latencies of opiorphin and saline groups.ConclusionThe results of this study suggest that the analgesic effect of opiorphin occurs at the spinal level and it is not as effective as morphine at supraspinal level. It may be due to rapid degradation of opiorphin or limited ability of opiorphin to cross the blood brain barrier or a higher dose of opiorphin is required for its action in the brain. Pharmacokinetic/pharmacodynamics studies along with in vivo penetration of opiorphin in the cerebrospinal fluid are required for further evaluation of opiorphin analgesia.

Enhanced antinociception with repeated microinjections of apomorphine into the periaqueductal gray of male and female rats.

Dopamine neurons in the ventrolateral periaqueductal gray (PAG) have been reported to contribute to antinociception. The objective of this study was to determine how this dopamine-mediated antinociception differs from what is known about morphine-induced antinociception. Microinjection of the dopamine receptor agonist apomorphine into the PAG produced a dose-dependent increase in hot plate latency and a decrease in open field activity that was greater in male than in female rats. The peak antinociceptive effect occurred 5 min after apomorphine administration. Surprisingly, the antinociceptive potency of apomorphine was enhanced following systemic administration of the opioid receptor antagonist naloxone in male, but not in female rats. The antinociceptive potency of microinjecting apomorphine into the ventrolateral PAG in male and female rats was also enhanced following twice-daily injections for 2 days. The characteristics of apomorphine-induced antinociception differ from previous reports of morphine antinociception following PAG microinjections in that morphine antinociception peaks at 15 min, is blocked by naloxone, and is susceptible to tolerance with repeated administration. These results indicate that apomorphine-induced antinociception is distinct from opioid-induced antinociception, and that dopamine receptor agonists may provide a novel approach to pain modulation.

An Evaluation of Neurotoxicity Following Fluoride Exposure from Gestational Through Adult Ages in Long-Evans Hooded Rats

At elevated levels, fluoride (F−) exposure has been associated with adverse human health effects. In rodents, F− exposure has been reported to induce deficits in motor performance and learning and memory. In this study, we examined Long-Evans hooded male rats maintained on a standard diet (20.5 ppm F−) or a low F− diet (3.24 ppm F−) with drinking water exposure to 0, 10, or 20 ppm F− from gestational day 6 through adulthood. At postnatal day 25, brain F− levels were 0.048 or 0.081 μg/g and femur 235 or 379.8 μg/g for 10 and 20 ppm F−, respectively. Levels increase with age and in adults, levels for plasma were 0.036 or 0.025 μg/ml; for the brain 0.266 or 0.850 μg/g; and for the femur, 681.2 or 993.4 μg/g. At these exposure levels, we observed no exposure-related differences in motor, sensory, or learning and memory performance on running wheel, open-field activity, light/dark place preference, elevated plus maze, pre-pulse startle inhibition, passive avoidance, hot-plate latency, Morris water maze acquisition, probe test, reversal learning, and Y-maze. Serum triiodothyronine (T3), thyroxine (T4), and thyroid stimulating hormone (TSH) levels were not altered as a function of 10 or 20 ppm F− in the drinking water. No exposure-related pathology was observed in the heart, liver, kidney, testes, seminal vesicles, or epididymides. Mild inflammation in the prostate gland was observed at 20 ppm F−. No evidence of neuronal death or glial activation was observed in the hippocampus at 20 ppm F−.

Evaluation of the effects of tramadol on analgesic response and locomotor activity on two different strains of laboratory mice

Analgesia of laboratory animals consists an important component in experimental studies where painful stimuli or procedures may take place. When choosing analgesics, the severity of pain along with the response to medication is among the factors that determine the choice of agent. Tramadol is a known synthetic opioid analgesic used to treat main acute or chronic pain including perioperative pain. The purpose of this study was to evaluate the analgesic response as well as the effect on locomotor activity in two different strains of mice after the intraperitoneal (i.p.) administration of tramadol. Subjects were 11-13 week-old male C57BL/6J (n=39) and BALB/cJ (n=38) mice, randomly assigned to receive either saline, tramadol 10 mg/kg or tramadol 40 mg/kg. Analgesia was measured using the hot-plate test, 30 or 60 minutes after drug administration while the open field test was used in order to assess locomotor activity. Both strains exhibited a significant increase of hot-plate latencies after administration of tramadol 40 mg/kg while the same dose induced significantly greater analgesia in BALB/cJ as compared with the C57BL/6J mice. BALB/cJ mice presented a dose-dependent decrease in locomotor activity following tramadol administration whereas C57BL/6J mice receiving 40 mg/kg tramadol showed hyperactivity. In conclusion, the lower dose of tramadol (10 mg/kg) has insufficient antinociceptive effects on acute thermal pain for both strains. The highest dose of tramadol used in this study (40 mg/kg) was greater than the one required for BALB/cJ mice, as they were under sedation for at least 60 minutes after drug administration. The same dose of tramadol appeared to be effective on C57BL/6J tramamice as latency times on the hot plate were significantly increased. Despite this fact, it is not a suitable choice as an analgesic, especially postoperatively, as it causes hyperactivity to this strain. Special concern should be given to the fact that tramadol’s analgesic and behavioral effects depend not only on its dosage, but also on the strain in which it is administered.

Antinociceptive tolerance to NSAIDs in the anterior cingulate cortex is mediated via endogenous opioid mechanism

BackgroundIn the past decade several studies have reported that in some brain areas, particularly, in the midbrain periaqueductal gray matter, rostral ventro-medial medulla, central nucleus of amygdala, nucleus raphe magnus, and dorsal hippocampus, microinjections of non-steroidal anti-inflammatory drugs (NSAIDs) induce antinociception with distinct development of tolerance. Given this evidence, in this study we investigated the development of tolerance to the analgesic effects of NSAIDs diclofenac, ketorolac and xefocam microinjected into the rostral part of anterior cingulate cortex (ACC) in rats.MethodsMale Wistar experimental and control (saline) rats were implanted with a guide cannula in the ACC and tested for antinociception following microinjection of NSAIDs into the ACC in the tail-flick (TF) and hot plate (HP) tests. Repeated measures of analysis of variance with post-hoc Tukey-Kramer multiple comparison tests were used for statistical evaluations.ResultsTreatment with each NSAID significantly enhanced the TF and HP latencies on the first day, followed by a progressive decrease in the analgesic effect over a 4-day period, i.e., developed tolerance. Pretreatment with an opioid antagonist naloxone completely prevented the analgesic effects of the three NSAIDs in both behavioral assays.ConclusionsThese findings support the concept that the development of tolerance to the antinociceptive effects of NSAIDs is mediated via an endogenous opioid system possibly involving descending pain modulatory systems.

Evaluation of Anti-Nociceptive and Anti-Inflammatory Effect of Luteolin in Mice

Flavonoids are polyphenolic compounds that not only impart coloration to plants and fruits, but also protect plants from pathogens, radiation, etc. They serve as a nutrient to plants and possess immense anti-oxidant properties. Research has shown that they exhibit anti-inflammatory, anti-cancer, and neuroprotective properties in both in vitro and in vivo analyses. Luteolin is one such flavonoid belongs to the group of flavones present in herbs such as thyme, chamomile, celery, and green pepper. The epidemiological data on luteolin consumption show that luteolin has anti-inflammatory activity and protects from diseases associated with inflammation. The present study assessed the anti-nociceptive properties of luteolin, a potent anti-inflammatory agent, in mice. The results demonstrated that luteolin produces a significant and dose-dependent increase in hot plate latency and tail withdrawal time. It also reduced the number of abdominal constrictions and paw licking induced by acetic acid and glutamate, respectively. Luteolin inhibited the nociceptive responses in both phases of formalin test. The anti-inflammatory property of luteolin was also confirmed with different anti-inflammatory mice models induced by carrageenan and air pouch. Behavioral changes in luteolin-treated mice were assessed with open-field test to confirm the muscle relaxant property. The results of the current study from various pain and inflammatory models confirms that luteolin possess potent anti-nociceptive and anti-inflammatory properties and can thus be used as a drug in pain management.

Neural tissue regeneration by a gabapentin-loaded cellulose acetate/gelatin wet-electrospun scaffold

In the present study, gabapentin (GBP), an anticonvulsant drug used as an analgesic to control the neuropathic pains, was incorporated with cellulose acetate (CA) and gelatin (Gel) in order to develop a potential scaffold for neural tissue engineering applications. The wet-electrospinning method was used to produce the drug-loaded three-dimensional scaffolds from CA/Gel [1:1 (w/w)] solution in the water/ethanol (3:7) (v/v) coagulation baths containing 3%, 6% and 12% (w/v) of GBP. The scaffolds were evaluated regarding their morphology, contact angle, porosity, tensile strength and cellular response. The scaffold obtained from 6% (w/v) GBP bath was chosen as the optimum scaffold for further in vivo study in a sciatic nerve defect model in Wistar rats. The results of sciatic functional index, hot plate latency, weight-loss percentage of the wet gastrocnemius muscle and the histopathological examination using hematoxylin–eosin staining demonstrated that the GBP-containing scaffold significantly enhanced the regeneration of the created injury, which demonstrates its applicability for neural tissue engineering applications.

Enhanced analgesic effects of nefopam in combination with acetaminophen in rodents.

Nefopam, an analgesic drug, effectively elicits antinociception in the majority of noxious and thermal models in rodents. Acetaminophen is among the most commonly used analgesic and antipyretic drugs worldwide, either on prescription or over the counter. The present study aimed to investigate the analgesic activity of nefopam combined with acetaminophen, which was expected to maximize the potency of analgesia and decrease the dose of nefopam required. Three series of experiments, namely acetic acid-induced writhing tests in mice, hot plate tests in mice and tail flick tests in rats, were used to evaluate the analgesic effect. Initially, an optimum proportion of the two drugs, 3.5 mg/kg nefopam (N) + 60 mg/kg acetaminophen (A), was determined by orthogonal array design based on writhing response number. Subsequently, combinations of N and A (1.75 N + 30 A, 3.5 N + 60 A and 7.0 N + 120 A mg/kg) were determined to elicit antinociception in the writhing test (P<0.01 vs. normal saline control) in a dose-dependent manner. In the hot plate test, hot plate latencies up to 60 min after drug treatment were observed. The combination of 7.0 N + 120 A mg/kg exerted a greater cumulative antinociceptive effect throughout the observation period, with an area under the curve value of 1,156.95±199.30 area units (AU), compared with that achieved by 7.0 N mg/kg alone (632.12±62.38 AU). Furthermore, both monotherapy and compound therapy exhibited antinociception dose-dependently in the tail-flick test. However, a combination of 5.0 N + 84 A mg/kg exerted greater analgesic effect compared with 5.0 N mg/kg alone. The data obtained demonstrate that acetaminophen may enhance the antinociceptive activity of nefopam. Thus, coadministration of nefopam with acetaminophen warrants clinical evaluation.

Neuroprotective effects of Moringa oleifera: Bio-guided GC-MS identification of active compounds in diabetic neuropathic pain model.

To explore the phytotherapeutic-activities of Moringa oleifera (MO) seeds on painful diabetic neuropathy in alloxan-induced diabetic mice. The bio-guided fractionation of MO utilizing column chromatography aided with GC-MS was used to detect the most active constituent of MO. Hyperalgesia, using tail-flick and hot-plate latency experiments, and mechanical-allodynia, utilizing von-Frey filaments, were evaluated before and after 8 weeks of intraperitoneal alloxan administration (180 mg/kg). Serum catalase and insulin levels, body weight and blood glucose levels (BGL), alpha-glucosidase inhibition, lipid peroxidation and glycated hemoglobin (HbA1c) were measured to evaluate both alloxan-induced diabetes mellitus and diabetic painful neuropathy (DPN). Beta-sitosterol (BSL) was proved to be the most active constituent of MO. The administration of MO (40, 60 and 80 mg/kg) or BSL (18, 25 and 35 mg/kg) significantly attenuated hyperalgesia and tactile allodynia (P⩽0.05), compared with tramadol (10 mg/kg) acting as a positive control, in alloxan-treated animals (n=7 per group). Moreover, MO and BSL have improved insulin secretion, in vivo antioxidant catalase, lipid peroxidation, acute and subchronic BGL, and normalized alpha-glucosidase and HbA1c levels. The observed insulin secretagogue, alpha-glucosidase inhibition, hypoglycemic and antioxidant potentials might be responsible for MO and BSL antinociception and neuroprotective mechanism. MO and BSL have shown good glycemic-control and powerful neuroprotective properties which might serve as potential lead-compounds for further analysis.

Evaluation of antioxidant, anti-inflammatory, analgesic and antipyretic activities of the stem bark of Sapindus mukorossi

BackgroundSaponins are the main constituents of genus Sapindus and have the therapeutic potential for inflammatory disorders. In this study the antioxidant, anti-inflammatory, analgesic and antipyretic potential of the stem bark of soap nut (Sapindus mukorossi) methanol extract and its derived fractions has been investigated.MethodsPowder of stem bark of the S. mukorossi was extracted with methanol (SMM) and fractionated in order of n-hexane (SMH), chloroform (SMC), ethyl acetate (SME), n-butanol (SMB) and the remaining as aqueous fraction (SMA). Quantitative estimation for the total phenolic and total flavonoid content was carried out in all the extract/fractions. Further, various in vitro antioxidant assays were also performed. Anti-inflammatory (Carrageenan induced paw edema), analgesic (hot plate latency test) and antipyretic (rectal temperature) were determined in Sprague-Dawley rat.ResultsQuantitative estimation of total phenolic contents in extract/fractions varied between 252.3 ± 2.41 mg of GAE/g - 594.16 ± 4.3 mg of GAE/g while the total flavonoids estimated were from 11.02 ± 1.3 mg of RUE/g to 96.9 ± 3.2 mg of RUE/g. Standard antioxidant assays such as scavenging of DPPH, hydroxyl radical, nitric oxide, phosphomolybdenum assay, reducing power, inhibition of β-carotene bleaching, iron chelation activity and inhibition of heat induced protein denaturation indicated the antioxidant potential of the extract/fractions. Carrageenan induced paw edema of rat was effectively inhibited by SMA at 300 mg/kg administration to rat (84.19 ± 1.48%) after 3 h and analgesia (latency time) in hot plate test (55.78 ± 1.22%) after 120 min. SMA at 300 mg/kg distinctly decreased the rectal temperature in brewer’s yeast (Saccharomyces cerevisiae) induced pyrexia in rat.ConclusionThe resulted obtained in this study suggested the therapeutic importance of stem bark of S. mukorossi in inflammatory related disorders.

Central noradrenergic activity affects analgesic effect of Neuropeptide S.

Neuropeptide S (NPS) is an endogenous neuropeptide controlling anxiolysis, wakefulness, and analgesia. NPS containing neurons exist near to the locus coeruleus (LC) involved in the descending anti-nociceptive system. NPS interacts with central noradrenergic neurons; thus brain noradrenergic signaling may be involved in NPS-induced analgesia. We tested NPS analgesia in noradrenergic neuron-lesioned rats using a selective LC noradrenergic neurotoxin, N-(2-chloroethyl)-N-ethyl-2-bromobenzylamine (DSP-4). A total 66 male Sprague-Dawley rats weighing 350-450g were used. Analgesic effects of NPS were evaluated using hot-plate and tail-flick test with or without DSP-4. The animal allocated into 3 groups; hot-plate with NPS alone intracerebroventricular (icv) (0.0, 1.0, 3.3, and 10.0nmol), tail-flick NPS alone icv (0.0 and 10.0nmol), and hot-plate with NPS and DSP-4 (0 or 50mg/kg ip). In hot-plate with NPS and DSP-4 group, noradrenaline content in the cerebral cortex, pons, hypothalamus, were measured. NPS 10nmol icv prolonged hot plate (%MPE) but not tail flick latency at 30 and 40min after administration. DSP-4 50mg/kg decreased noradrenaline content in the all 3 regions. The NA depletion inhibited NPS analgesic effect in the hot plate test but not tail flick test. There was a significant correlation between hot plate latency (percentage of maximum possible effect: %MPE) with NPS 10nmol and NA content in the cerebral cortex (p=0.017, r 2=0.346) which noradrenergic innervation arisen mainly from the LC. No other regions had the correlation. NPS analgesia interacts with LC noradrenergic neuronal activity.

Calcitonin potentiates the anticonvulsant and antinociceptive effects of valproic acid and pregabalin in pentylenetetrazole-kindled mice

Antiepileptic drugs are the backbone for epilepsy management. Epilepsy may be accompanied by decreased pain threshold. Thus, anticonvulsant agents with antinociceptive properties are of great importance. This study investigated the possible anticonvulsant and antinociceptive effects of calcitonin in combination with either valproic acid or pregabalin and whether these effects might occur through γ-aminobutyric acid (GABA) modulation.Eighty-four male Balb/C mice were divided into 7 groups: control-naïve, pentylenetetrazole (PTZ)-induced seizures, PTZ-calcitonin, PTZ-valproic acid, PTZ-pregabalin, PTZ-calcitonin-valproic acid (PCV) combination, and PTZ-calcitonin-pregabalin (PCP) combination. PTZ was used in a sub-convulsive dosage, every other day for 11 injections. Drugs were given i.p. 30min before PTZ. After each PTZ injection, mice were put under observation and PTZ-provoked seizures were assessed. After the last dose of PTZ, the hot plate test was used to assess antinociceptive properties. Also, brain GABA neurotransmitter was evaluated by immunoassay.Repeated injection of PTZ induced chemical kindling. Calcitonin was found to have significant antinociceptive property as shown by hot plate latency. The beneficial effects of PCV and PCP combination were statistically significant in epilepsy and pain models as compared to valproic acid and pregabalin. The antiepileptic and antinociceptive activity of calcitonin may not relate to the GABAergic system.Calcitonin enhanced the anticonvulsant and antinociceptive effects of either valproic acid or pregabalin. This new treatment “calcitonin add-on” may provide an improved range of options for patients with refractory epilepsy which is still an important risk factor for sudden death.

Sciatic nerve regeneration by transplantation of menstrual blood-derived stem cells.

This is the first study demonstrating the efficacy of menstrual blood-derived stem cell (MenSC) transplantation via a neural guidance conduit, for peripheral nerve regeneration. The synthesized poly (ɛ-caprolactone)/Gelatin conduit, filled with collagen type I and seeded with 3 × 104 MenSCs, was implanted into a rat's 10mm sciatic nerve defect. The results of hot plate latency, sciatic functional index and weight-loss percentage of wet gastrocnemius muscle demonstrated that the MenSC transplantation had comparable nerve regeneration outcome to autograft, as the gold standard of nerve bridging. The transplantation of MenSCs via a synthetic conduit could ameliorate the functional recovery of sciatic nerve-injured rats which make them a potential candidate for cell therapy of peripheral nervous system disorders.

Regeneration of sciatic nerve crush injury by a hydroxyapatite nanoparticle-containing collagen type I hydrogel.

The current study aimed to enhance the efficacy of peripheral nerve regeneration using a hydroxyapatite nanoparticle-containing collagen type I hydrogel. A solution of type I collagen, extracted from the rat tails, was incorporated with hydroxyapatite nanoparticles (with the average diameter of~212nm) and crosslinked with 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide (EDC) to prepare the hydrogel. The Schwann cell cultivation on the prepared hydrogel demonstrated a significantly higher cell proliferation than the tissue culture plate, as positive control, after 48h (n=3, P<0.005) and 72h (n=3, P<0.01). For in vivo evaluation, the prepared hydrogel was administrated on the sciatic nerve crush injury in Wistar rats. Four groups were studied: negative control (with injury but without interventions), positive control (without injury), collagen hydrogel and hydroxyapatite nanoparticle-containing collagen hydrogel. After 12weeks, the administration of hydroxyapatite nanoparticle-containing collagen significantly (n=4, P<0.005) enhanced the functional behavior of the rats compared with the collagen hydrogel and negative control groups as evidenced by the sciatic functional index, hot plate latency and compound muscle action potential amplitude measurements. The overall results demonstrated the applicability of the produced hydrogel for the regeneration of peripheral nerve injuries.