Evidence for the involvement of glutamatergic system in the antinociceptive effect of ascorbic acid

Unveiling the potential impact of vitamin C in postoperative spinal pain

BACKGROUND

Spinal surgery is a common procedure associated with significant postoperative pain, and identifying effective interventions to manage this pain is crucial for optimizing patient outcomes. This review assesses the existing literature to determine the overall impact of vitamin C supplementation on spinal postoperative pain. Vitamin C, also known as ascorbic acid, is an essential nutrient that plays a vital role in numerous physiological processes. It functions as a potent antioxidant, neutralizing free radicals and reducing oxidative stress within the body. Furthermore, vitamin C is a cofactor in collagen synthesis, a crucial component of connective tissues, including those found in the spinal structures. Given its antioxidant and collagen-promoting properties, vitamin C has piqued interest as a potential therapeutic option for postoperative spinal pain. Based on the available evidence, vitamin C may have a beneficial effect on postoperative spinal pain, including reducing pain scores, analgesic consumption, and the incidence of complications such as complex regional pain syndrome. However, more research is needed to fully understand the optimal dosage and duration of vitamin C supplementation for postoperative pain management.

CONCLUSION

Vitamin C could be considered a potentially beneficial adjunctive therapy for managing spinal postoperative pain, but its routine use requires further investigation.

Vitamin C and catheter-related bladder discomfort after transurethral resection of bladder tumor: A double-blind, randomized, placebo-controlled study

STUDY OBJECTIVE

We evaluated the effect of vitamin C administration on postoperative catheter-related bladder discomfort (CRBD).

DESIGN

A double-blind, randomized controlled trial.

SETTING

University tertiary hospital.

PATIENTS

The participants were patients undergoing transurethral resection of bladder tumor.

INTERVENTION

Patients were randomly assigned to either vitamin C (n = 59) or control (n = 59). The vitamin C group received 1 g of vitamin C intravenously and the control group received normal saline, administered after the induction of anesthesia.

MEASUREMENTS

The primary endpoint was moderate or greater CRBD immediately postoperatively. Secondary outcomes included the incidence of moderate or greater CRBD at 1, 2, and 6 h postoperatively. The symptom of CRBD is either a burning sensation with an urge to void or discomfort in the suprapubic area. Moderate CRBD was defined as spontaneously reported by the patient without any behavioral responses, such as attempts to remove the urinary catheter, intense verbal reactions, and flailing limbs. Severe CRBD was spontaneously reported by the patient with behavioral responses. Patient satisfaction scores were also evaluated.

MAIN RESULTS

The group that received vitamin C exhibited a significantly lower incidence of moderate or greater CRBD immediately postoperatively compared with the control group (17 [28.8%] vs. 40 [67.8%], p < 0.001, relative risk [95% confidence interval] = 0.426 [0.274-0.656]). The vitamin C group also showed a significantly lower incidence of moderate or greater CRBD at 1 and 2 h postoperatively compared with the control group (10 [16.9%] vs. 25 [42.4%], p = 0.003; and 5 [8.5%] vs. 16 [27.1%], p = 0.008, respectively). However, there was no significant difference in the incidence of moderate or greater CRBD 6 h postoperatively. Patient satisfaction scores were significantly higher in the vitamin C group than in the control group (5.0 ± 1.3 vs. 4.4 ± 1.4, p = 0.009).

CONCLUSIONS

Patients who received vitamin C had decreased CRBD and improved patient satisfaction following transurethral resection of bladder tumor.

Honey on brain health: A promising brain booster

Since ancient times, honey has been employed in many aspects of everyday life, the most popular of which is as a natural sweetener. Honey is used not only as a nutritional product but also in health as a supplement and in various applications, especially related to brain booster health. Brain health is the capacity to carry out all mental functions necessary for cognition, such as learning and judging, utilizing language, and recalling. This review presents the current trend of research on honey, particularly the interest in underlying mechanisms related to brain booster health. A total of 34 original articles addressing brain health from the consumption of honey were analyzed. We identified four main brain health benefits, which are memory booster, neuroprotective effect, anti-stress, and anti-nociceptive potentials with the proposed underlying mechanism. A lot of attention has been paid to the role that honey plays in brain health research, with the goal of examining the link between honey and brain health as well as the mechanism underlying it, the findings from this review may be potentially beneficial to develop new therapeutic roles for honey to help determine the best and most promising to benefit and boost overall brain health.

Mechanisms of Actions Involved in The Antinociceptive Effect of Estragole and its β-Cyclodextrin Inclusion Complex in Animal Models

(1) Background: estragole is a monoterpene found in the essential oils of several aromatic plants, which can be used for several pharmacological activities. The aim of this study was to evaluate the antinociceptive effect of estragole (Es) and its β-cyclodextrins inclusion complex (Es/β-CD). (2) Methods: the effects of Es and Es/β-CD on the central nervous system (CNS) were evaluated through open field and rota-rod assays, and the antinociceptive effect in formalin models, abdominal writhing induced by acetic acid, hot plate, tail flick test and plantar mechanical hyperalgesia. (3) Results: Es and Es/β-CD showed no alterations on the CNS evaluated parameters and the results suggested there was an antinociceptive action in the formalin, abdominal writhing, hot plate, tail flick tests and plantar mechanical hyperalgesia, proposing the involvement of the nitric oxide, glutamatergic signaling pathways, cyclic guanosine monophosphate and vanilloid pathways. (4) Conclusion: the results suggest that Es and Es/β-CD have a promising antinociceptive potential as a possible alternative for the pharmacological treatment of pain, also showing that the encapsulation of Es in β-cyclodextrins probably improves its pharmacological properties, since the complexation process involves much lower amounts of the compound, contributing to better bioavailability and a lower probability of adverse effect development.

Myrciaria dubia Juice (camu-camu) Exhibits Analgesic and Antiedematogenic Activities in Mice

The Myrciaria dubia (Myrtaceae) fruit is traditionally used to treat malnutrition due to its high levels of vitamin C and phenolic compounds. Because of its composition, this plant is very promising in the research of novel natural treatment for pain disorders. This study analyzed the phytochemical profile of M. dubia juice and assessed its antinociceptive and antiedematogenic potential. The phytochemical profile was determined through high-performance liquid chromatography (HPLC), the oral antinociceptive effect of M. dubia 50% juice (Md50) was evaluated by formalin, hot plate and Complete Freund's Adjuvant tests and the antiedematogenic activity by paw edema. HPLC revealed the presence of ascorbic acid, rutin, and ellagic acid as major compounds. Md50 showed an antinociceptive effect in the acute and chronic phases of the formalin test. In the hot plate test, Md50 also induced an antinociceptive effect of 0.5 up to 6 h, showing antinociceptive and antiedematogenic potential without changing the spontaneous locomotion of animals. All protocols were submitted and approved by the Ethics Committee for use of Animals of the Lutheran University of Brazil (protocol No. 2013-30P).

The Effect of Perioperative Vitamin C on Postoperative Analgesic Consumption: A Meta-Analysis of Randomized Controlled Trials

Because the analgesic effect of vitamin C against acute pain remains poorly addressed, this meta-analysis aimed at investigating its effectiveness against acute postoperative pain. A total of seven randomized controlled trials with placebo/normal controls were identified from PubMed, Cochrane Library, Medline, Google Scholar, and Embase databases. Pooled analysis showed a lower pain score (standardized mean difference (SMD) = -0.68, 95% CI: -1.01 to -0.36, p < 0.0001; I2 = 57%) and a lower morphine consumption (weighted mean difference (WMD) = -2.44 mg, 95% CI: -4.03 to -0.86, p = 0.003; I2 = 52%) in the vitamin group than that in the placebo group within postoperative 1-2 h. At postoperative 24 h, a lower pain score (SMD = -0.65, 95% CI: -1.11 to -0.19, p = 0.005; I2 = 81%) and lower morphine consumption (WMD = -6.74 mg, 95% CI: -9.63 to -3.84, p < 0.00001; I2 = 85%) were also noted in the vitamin group. Subgroup analyses demonstrated significant reductions in pain severity and morphine requirement immediately (1-2 h) and 24 h after surgery for patients receiving intravenous vitamin C but not in the oral subgroup. These findings showed significant reductions in pain score and opioid requirement up to postoperative 24 h, respectively, suggesting the effectiveness of perioperative vitamin C use. Further large-scale trials are warranted to elucidate its optimal intravenous dosage and effectiveness against chronic pain in the postoperative pain control setting.

Additional effect of magnesium sulfate and vitamin C in laparoscopic gynecologic surgery for postoperative pain management: a double-blind randomized controlled trial

Background

This clinical trial was conducted to determine whether combined use of magnesium sulfate and vitamin C more significantly reduced postoperative fentanyl consumption and pain than magnesium sulfate or vitamin C alone.

Methods

The prospective, double-blinded, randomized controlled study enrolled 132 patients scheduled for laparoscopic gynecologic surgery. The patients were randomly allocated to one of the four groups (n = 33 for each group; Group M [magnesium sulfate 40 mg/kg], Group V [vitamin C 50 mg/kg], Group MV [magnesium sulfate 40 mg/kg and vitamin C 50 mg/kg] and Group C [isotonic saline 40 ml]). Cumulative postoperative fentanyl consumption (primary endpoint measure), postoperative pain score by numeric rating scale, and postoperative nausea and vomiting were recorded at 1, 6, 24, and 48 h after discharge from the postanesthesia care unit.

Results

Cumulative postoperative fentanyl consumption was significantly less in Groups M, V, and MV than in Group C at all time points. Group MV showed significantly less cumulative postoperative fentanyl consumption than Group M at postoperative 24 h (mean ± standard deviation, 156.6 ± 67.5 vs. 235.6 ± 94.6 µg, P = 0.001), as well as significantly less consumption than Groups M and V at postoperative 48 h (190.8 ± 74.6 vs. 301.0 ± 114.8 or 284.1 ± 128.6 µg, P < 0.001, P = 0.003, respectively).

Conclusions

Combined use of magnesium sulfate and vitamin C provides an additional benefit in postoperative pain management after laparoscopic gynecologic surgery in comparison to single administration of magnesium sulfate or vitamin C.

Functional interaction between N-methyl-D-aspartate receptor and ascorbic acid during neuropathic pain induced by chronic constriction injury of the sciatic nerve

BACKGROUND

Neuropathic pain is a chronic pain condition, which is resistant to therapy. Ascorbate was released because of the activation of glutaminergic neurons. Due to the important role of N-methyl-D-aspartate (NMDA) receptors in the pathophysiology of neuropathic pain, this study investigated the analgesic efficacy of ascorbic acid (AA) in neuropathic pain condition and the role of NMDA receptors in this effect.

METHODS

For this purpose, adult male rats were randomly allocated to experimental groups (n=8 in each group). Neuropathic pain was induced by chronic constriction injury (CCI) of the sciatic nerve. During the second week after CCI, animals received a single injection of 1, 3, 5, or 10 mg/kg of AA intraperitoneally and pain threshold was determined 15 and 60 min later. The antinociceptive effect of chronic administration was also evaluated by intraperitoneal injection (IP) of 3 mg/kg AA for 3 weeks. To determine the role of NMDA receptors, separate groups of animals 30 min after single injection of AA (1 mg/kg) animals received i.p. injection of ketamine (5 mg/kg), MK-801 (0.01 mg/kg), or glutamate (1000 nmol) and were tested 20 min afterwards. Data analyzed by ANOVA and Newman-Keuls tests and p<0.05 were considered as significant.

RESULTS

IP of 3, 5 and 10 mg/kg increased the pain threshold during the second week after CCI (p<0.05, F=3 in tactile allodynia and p<0.01, F=3.2 in thermal and mechanical hyperalgeisa). Chronic administration of AA also produced antinociceptive effect. Ascorbic acid (1 mg/kg, i.p.) inhibited MK-801 and ketamine-induced antinociception response significantly (p<0.001, F=2). It also prevented the analgesic effect of glutamate administration (p<0.001, F=2).

CONCLUSIONS

The results indicated that AA produced a dose-dependent antinociceptive effect that seems to mediate through its interaction with NMDA receptors.

The Efficacy of Vitamin C on Postoperative Outcomes after Posterior Lumbar Interbody Fusion: A Randomized, Placebo-Controlled Trial

Background

Vitamin C has critical features relavant to postoperative pain management and functional improvement; however, no study has yet evaluated the effectiveness of vitamin C on improving the surgical outcomes for spine pathologies. Thus, this study aimed to explore the impact of vitamin C on postoperative outcomes after single-level posterior lumbar interbody fusion (PLIF) for lumbar spinal stenosis in prospectively randomized design. We conducted a 1-year prospective, randomized, placebo-controlled, double-blind study to evaluate the impact of vitamin C on the postoperative outcomes after PLIF surgery.

Methods

A total of 123 eligible patients were randomly assigned to either group A (62 patients with vitamin C) or group B (61 patients with placebo). Patient follow-up was continued for at least 1 year after surgery. The primary outcome measure was pain intensity in the lower back using a visual analogue scale. The secondary outcome measures were: (1) the clinical outcome assessed using the Oswestry Disability Index (ODI); (2) the fusion rate assessed using dynamic radiographs and computed tomography scans; and (3) complications.

Results

Pain intensity in the lower back was significantly improved in both groups compared with preoperative pain intensity, but no significant difference was observed between the 2 groups over the follow-up period. The ODI score of group A at the third postoperative month was significantly higher than the score of group B. After the sixth postoperative month, the ODI score of group A was slightly higher than the score of group B; however, this difference was not significant. The fusion rates at 1 year after surgery and the complication rates were not significantly different between the 2 groups.

Conclusions

Postoperative pain intensity, the primary outcome measure, was not significantly different at 1 year after surgery between the 2 groups. However, vitamin C may be associated with improving functional status after PLIF surgery, especially during the first 3 postoperative months.

Effect of Intravenous High Dose Vitamin C on Postoperative Pain and Morphine Use after Laparoscopic Colectomy: A Randomized Controlled Trial

Background and Objective. Vitamin C has antioxidant, neuroprotective, and neuromodulating effects. Recently, it showed antinociceptive effect as a result of the antioxidant properties. Therefore, we designed this study to assess the effect of intravenous vitamin C on opiate consumption and pain in patients undergoing laparoscopic colectomy. Methods. A total of 100 patients were enrolled and allocated to receive 50 mg/kg vitamin C or placebo by intravenous infusion immediately after induction of anesthesia. Morphine consumption and scores of pain were assessed at 2, 6, and 24 h after completion of surgery. Results. There were 97 patients included in the analysis. Patients who received vitamin C had higher plasma concentrations of vitamin C at the end of surgery, significantly lower morphine consumption at the 2 h after end of surgery, and significantly lower pain scores at rest during first 24 h postoperatively. There was no significant difference between groups in side effects, fatigue score, or pain score during cough. Conclusion. This study shows high dose vitamin C infusion decreased postoperative pain during the first 24 h and reduced morphine consumption in the early postoperative period. Additional research needed to examine whether higher doses of vitamin C and longer infusion times can amplify these effects.

Vitamin C enhances the analgesic effect of gabapentin on rats with neuropathic pain

AIMS

Gabapentin (Gap) relieves neuropathic pain, but it has several adverse effects as well. We aimed to investigate whether vitamin C (VitC) supplementation would reduce the effective dose of Gap for analgesia in rats with chronic constriction injury (CCI).

MAIN METHODS

Rats were randomly assigned to Sham, CCI, VitC, Gap, and VitC+Gap treatment groups. CCI, involving the left sciatic nerve, was induced in all animals except the Sham group. VitC (500mg/kg (body weight)), Gap (10, 30, or 100mg/kg), or VitC (500mg/kg)+Gap (10, 30, or 100mg/kg) were injected intraperitoneally twice daily for a week from 7days after sham or CCI surgery. Mechanical paw withdrawal threshold (PWT), thermal paw withdrawal latency (PWL) and malondialdehyde (MDA) content in serum or spinal cord tissues were all measured. The expression of sodium dependent vitamin C transporter 2 (SVCT2) and glucose transporter 3 (GLUT3) in dorsal root ganglion (DRG) were detected by quantitative real-time PCR, Western blot and immunohistochemistry.

KEY FINDINGS

No more than 30mg/kg Gap could restore the decrease of PWT or PWL induced by CCI so long as combined with 500mg/kg VitC. For mechanism study, we found that VitC supplementation would remarkedly ameliorate oxidative stress in peripheral blood, and possibly cause a positive feedback in VitC uptake of neurons in DRG by promoting SVCT2 expression.

SIGNIFICANCE

Vitamin C can enhance gabapentin's analgesic effect. And the underlying mechanism may be concerned with antioxidative responses which were more obvious in peripheral blood than in the neurons.

The antinociceptive effects of tualang honey in male sprague-dawley rats: a preliminary study

Tualang honey (蜂蜜 Fēng Mì) is known to have anti-inflammatory property, but its antinociceptive property has not been extensively investigated. In this study, we examined the preemptive effects on administering different doses of Tualang honey and prednisolone on the nociceptive response in male Sprague-Dawley rats. Thirty-five male Sprague-Dawley rats were randomized into five groups (n = 7) and each group received either distilled water, Tualang honey (0.2, 1.2 or 2.4 g/kg) or prednisolone (10 mg/kg) for 10 days. The response to noxious thermal stimulus was assessed using tail flick test on Day 10. The well-being of the rats was also assessed by monitoring their food intake and body weight. Data were analyzed using one-way Analysis of Variance (ANOVA) with post-hoc Scheffe's test and P value less than 0.05 was considered significant. In tail flick test, the tail flick latency time was significantly higher in the groups that received 1.2 g/kg and 2.4 g/kg of Tualang honey and 10 mg/kg of prednisolone, compared to the control group (P < 0.05). There was significant reduction in the total food pellet intake in the groups receiving prednisolone and Tualang honey (1.2 g/kg and 2.4 g/kg) compared to controls; however, the body weight gain was only significantly reduced in the prednisolone group. All the parameters were not significantly affected in the group receiving 0.2 g/kg of Tualang honey. In conclusion, preemptive administration of Tualang honey (1.2 g/kg and 2.4 g/kg) and prednisolone (10 mg/kg) had reduced the pain responses. The reduced weight gain in the prednisolone group is an unwanted effect due to its metabolic and central actions. Further studies are required to confirm the antinociceptive effects and elucidate the mechanism of antinociceptive action of Tualang honey in the rats.

Ascorbic Acid interaction with analgesic effect of morphine and tramadol in mice

Background:

Combining different analgesic drugs for improvement of drug efficacy is a recommended strategy intended to achieve the optimal therapeutic effects.

Objectives:

The purpose of the present study was to assess the nature of the interaction between ascorbic acid and two analgesic drugs, morphine and tramadol.

Materials and Methods:

The analgesic activity was assessed by the acetic acid writhing test in male Naval Medical Research Institute (NMRI) mice. The results were obtained using four to six animals in each group. All the drugs were injected intraperitoneally. The effective doses (ED) that produced 20%, 50%, and 65% antinociception (ED₂₀, ED₅₀ and ED₆₅) were calculated from the dose-response curve of each drug alone as well as co-administration of ascorbic acid and tramadol or morphine. The interaction index was calculated as experimental ED/theoretical ED. For each drug combination, ED₅₀, ED₂₀ and ED₆₅ were determined by linear regression analysis of the dose-response curve, and they were compared to theoretical ED₅₀, ED₂₀ and ED₆₅ using t-test.

Results:

The antinociceptive effects of all drugs were dose-dependent (ED₅₀was 206.1 mg/kg for ascorbic acid, 8.33 mg/kg for tramadol, and 0.79 mg/kg for morphine). The interaction index demonstrated additive effects at ED₅₀ and ED₆₅ for co-administration of ascorbic acid and tramadol or morphine. However, at ED₂₀, combination of ascorbic acid and tramadol or morphine showed synergic effects. The interaction index values of the combinations demonstrated the potency ratio of ascorbic acid/morphine to be lower than ascorbic acid/tramadol.

Conclusions:

This study demonstrated the results of interactions between ascorbic acid and tramadol or morphine. The results showed that the interaction effects on antinociception may be synergistic or additive, depending on the level of effect.

Antidepressant-like effect of ascorbic acid is associated with the modulation of mammalian target of rapamycin pathway

The present study investigated the involvement of the PI3K, GSK-3β, heme oxygenase-1 (HO-1) and mTOR in the antidepressant-like effect of ascorbic acid in the tail suspension test (TST). Male Swiss mice were pretreated with ascorbic acid (1 mg/kg, p.o.) or vehicle and 45 min after, LY294002 (10 μg/site, i.c.v., reversible PI3K inhibitor), rapamycin (0.2 nmol/site, i.c.v., selective mTOR inhibitor), zinc protoporphyrin (ZnPP - 10 ng/site, i.c.v., HO-1 inhibitor) or vehicle was administered. We also investigated the synergistic effect of ascorbic acid (0.1 mg/kg, p.o., sub-effective dose in the TST) with lithium chloride (10 mg/kg, p.o., non-selective GSK-3β inhibitor), AR-A014418 (0.01 μg/site, i.c.v., selective GSK-3β inhibitor) or cobalt protoporphyrin (CoPP - 0.01 μg/site, i.c.v., HO-1 inducer) in the TST. The antidepressant-like effect of ascorbic acid (1 mg/kg, p.o.) was prevented by the treatment of mice with LY294002, rapamycin or ZnPP. In addition, sub-effective doses of lithium chloride, AR-A014418 or CoPP, combined with a sub-effective dose of ascorbic acid produced a synergistic antidepressant-like effect. We also demonstrated that 1 h after its administration, ascorbic acid increased the phosphorylation of p70S6K and the immunocontent of PSD-95 in the hippocampus of mice. These results indicate that the antidepressant-like effect of ascorbic acid in the TST might be dependent on the activation of PI3K and mTOR, inhibition of GSK-3β as well as induction of HO-1, reinforcing the notion that these are important targets for antidepressant activity and contributing to better elucidate the mechanisms underlying the antidepressant-like effect of ascorbic acid.

Antiallodynic effects of vitamin C and vitamin E in chronic post-ischemia pain rat model

Background

Recent research has shown that reactive oxygen species (ROS) play a significant role in the development and persistence of neuropathic pain through central sensitization via N-methyl-D-aspartate (NMDA) receptor activation. In the present study, we examined whether the intraperitoneal administration of vitamins C and E alone or together could alleviate mechanical allodynia in a chronic post-ischemia pain (CPIP) rat model.

Methods

Vitamins C and E were administered intraperitoneally to 48 male Sprague Dawley rats once per day for 3 days before hindpaw ischemia-reperfusion (I/R) injury was induced. On the third day, the CPIP rat model was produced by inducing ischemia in the left hindpaw by applying an O-ring for 3 h, followed by reperfusion. Three days after reperfusion, hindpaw mechanical allodynia was assessed by measuring the withdrawal response to von Frey filament stimulation. The rats were sacrificed immediately after behavioral testing to determine the phosphorylated NMDA receptor subunit 1 (pNR1) and extracellular-signal-regulated kinases (pERK) levels in the spinal cord.

Results

When the antioxidant vitamins C and E were administered intraperitoneally to CPIP rats, I/R injury-induced mechanical allodynia was attenuated, and pNR1 and pERK levels were decreased in the rat spinal cord. Additionally, the co-administration of both vitamins had an increased antiallodynic effect.

Conclusions

The reduced phosphorylated NR1 and ERK levels indicate that vitamins C and E inhibit the modulation of spinal cord neuropathic pain processing. Co-administration of vitamins C and E had a greater antiallodynic effect.

Topical application of disodium isostearyl 2-O-L-ascorbyl phosphate, an amphiphilic ascorbic acid derivative, reduces neuropathic hyperalgesia in rats

BACKGROUND AND PURPOSE

Ca(v) 3.2 T-type calcium channels, targeted by H(2) S, are involved in neuropathic hyperalgesia in rats and ascorbic acid inhibits Ca(v) 3.2 channels. Therefore, we evaluated the effects of intraplantar (i.pl.) administration of ascorbic acid or topical application of disodium isostearyl 2-O-L-ascorbyl phosphate (DI-VCP), a skin-permeable ascorbate derivative on hyperalgesia induced by NaHS, an H(2) S donor, and on neuropathic hyperalgesia.

EXPERIMENTAL APPROACH

In rats mechanical hyperalgesia was evoked by i.pl. NaHS, and neuropathic hyperalgesia was induced by L5 spinal nerve cutting (L5SNC) or by repeated administration of paclitaxel, an anti-cancer drug. Dermal ascorbic acid levels were determined colorimetrically.

KEY RESULTS

The NaHS-evoked Ca(v) 3.2 channel-dependent hyperalgesia was inhibited by co-administered ascorbic acid. Topical application of DI-VCP, but not ascorbic acid, prevented the NaHS-evoked hyperalgesia, and also increased dermal ascorbic acid levels. Neuropathic hyperalgesia induced by L5SNC or paclitaxel was reversed by i.pl. NNC 55-0396, a selective T-type calcium channel blocker, ascorbic acid or DI-VCP, and by topical DI-VCP, but not by topical ascorbic acid. The effects of i.pl. ascorbic acid and topical DI-VCP in the paclitaxel-treated rats were characterized by the faster onset and greater magnitude, compared with their effects in the L5SNC rats. Dermal ascorbic acid levels in the hindpaw significantly decreased after paclitaxel treatment, but not L5SNC, which was reversed by topical DI-VCP.

CONCLUSIONS AND IMPLICATIONS

Ascorbic acid, known to inhibit Ca(v) 3.2 channels, suppressed neuropathic hyperalgesia. DI-VCP ointment for topical application may be of benefit in the treatment of neuropathic pain.

Effect of vitamin C on morphine use after laparoscopic cholecystectomy: a randomized controlled trial

PURPOSE

We designed a randomized double-blind placebo-controlled trial to assess the role of a single prophylactic dose of vitamin C (2 g) po in reducing the consumption of opioids postoperatively in patients undergoing laparoscopic cholecystectomy.

METHODS

Eighty adult patients were allocated to receive 2 g vitamin C po or placebo approximately one hour prior to induction of anesthesia. Following laparoscopic cholecystectomy, patients received morphine patient-controlled analgesia for 24 hr. The following data were assessed postoperatively in the postanesthesia care unit at two, four, six, 12, and 24 hr: morphine consumption, verbal numerical rating scale scores for incisional pain and nausea/vomiting, and pruritus and sedation scores. The primary outcome measure was 24-hr morphine consumption. Patient satisfaction was assessed before hospital discharge.

RESULTS

Morphine consumption was significantly lower in the vitamin C group vs the placebo group [16.2 (10.7) and 22.8 (13.8) mg, respectively; difference = 6.6 mg; 95% confidence interval, 1.1 to 12.1 mg; P = 0.02]. There was no difference in pain scores or side effects between the two groups. Satisfaction scores were similar in both groups.

CONCLUSION

Our study showed that supplementation with vitamin C (2 g) po decreased morphine consumption in the postoperative period in patients undergoing laparoscopic cholecystectomy.

Ascorbic acid treatment, similarly to fluoxetine, reverses depressive-like behavior and brain oxidative damage induced by chronic unpredictable stress

Reactive oxygen species (ROS) have been shown to play a role in the pathophysiology of depression. Taking into account that experimental chronic unpredictable stress (CUS) induces depressive-like behavior and that ascorbic acid has antidepressant-like effect in animals, the objective of this study was to investigate the influence of ascorbic acid on depressive-like behavior induced by CUS paradigm, serum corticosterone levels and markers of oxidative stress in cerebral cortex and hippocampus of mice. Animals were submitted to CUS procedure during 14 days. From the 8th to the 14th day mice received ascorbic acid (10 mg/kg) or fluoxetine (10 mg/kg, conventional antidepressant, positive control) once a day by oral route. On 15th day behavioral and biochemical parameters were analyzed. CUS exposure caused a depressive-like behavior evidenced by the increased immobility time in the tail suspension test and decreased time in which mice spent grooming in the splash test. Depressive-like behavior induced by CUS was accompanied by a significant increased lipid peroxidation (cerebral cortex and hippocampus), decreased catalase (CAT) (cerebral cortex and hippocampus) and glutathione reductase (GR) (hippocampus) activities and reduced levels of glutathione (cerebral cortex). Repeated ascorbic acid or fluoxetine administration significantly reversed CUS-induced depressive-like behavior and oxidative damage. No alteration was observed in locomotor activity, corticosterone levels and glutathione peroxidase (GPx) activity. These findings indicate a rapid and robust effect of ascorbic acid in reversing behavioral and biochemical alterations induced by CUS in mice, suggesting that this vitamin may be an alternative approach for the management of depressive symptoms.

Additive antinociceptive effects of a combination of vitamin C and vitamin E after peripheral nerve injury

Accumulating evidence indicates that increased generation of reactive oxygen species (ROS) contributes to the development of exaggerated pain hypersensitivity during persistent pain. In the present study, we investigated the antinociceptive efficacy of the antioxidants vitamin C and vitamin E in mouse models of inflammatory and neuropathic pain. We show that systemic administration of a combination of vitamins C and E inhibited the early behavioral responses to formalin injection and the neuropathic pain behavior after peripheral nerve injury, but not the inflammatory pain behavior induced by Complete Freund's Adjuvant. In contrast, vitamin C or vitamin E given alone failed to affect the nociceptive behavior in all tested models. The attenuated neuropathic pain behavior induced by the vitamin C and E combination was paralleled by a reduced p38 phosphorylation in the spinal cord and in dorsal root ganglia, and was also observed after intrathecal injection of the vitamins. Moreover, the vitamin C and E combination ameliorated the allodynia induced by an intrathecally delivered ROS donor. Our results suggest that administration of vitamins C and E in combination may exert synergistic antinociceptive effects, and further indicate that ROS essentially contribute to nociceptive processing in special pain states.

Involvement of nitric oxide-cGMP pathway in the antidepressant-like effect of ascorbic acid in the tail suspension test

Clinical and preclinical data reported that ascorbic acid has antidepressant properties. The present study was designed to investigate the participation of l-arginine-NO-cGMP pathway in the antidepressant-like effect of ascorbic acid in the tail suspension test (TST) in mice. The antidepressant-like effect of ascorbic acid (1mg/kg, p.o.) in the TST was prevented by the pre-treatment of mice with NMDA (0.1pmol/site, i.c.v.), l-arginine (750mg/kg, i.p., a substrate for nitric oxide synthase) or sildenafil (5mg/kg, i.p., a phosphodiesterase 5 inhibitor). The administration of MK-801 (0.001mg/kg, i.p), 7-nitroindazole (25mg/kg, i.p., a neuronal nitric oxide synthase inhibitor) or ODQ (30pmol/site i.c.v., a soluble guanylate cyclase inhibitor) in combination with a sub-effective dose of ascorbic acid (0.1mg/kg, p.o.) reduced the immobility time in the TST test when compared with either drug alone. None of the results in the TST appears to be due to a nonspecific locomotor effect. Our findings provide evidence that the effect of ascorbic acid in the TST involve an interaction with NMDA receptors and l-arginine-NO-cGMP pathway, contributing to the understanding of the mechanisms underlying the antidepressant-like effect of this vitamin.

The antinociceptive effects of AR-A014418, a selective inhibitor of glycogen synthase kinase-3 beta, in mice

We investigated the antinociceptive effects of AR-A014418, a selective inhibitor of glycogen synthase kinase-3β (GSK-3β) in mice. A 30-minute pretreatment with AR-A014418 (.1 and 1 mg/kg, intraperitoneal [ip]) inhibited nociception induced by an ip injection of acetic acid. AR-A014418 pretreatment (.1 and .3 mg/kg, ip) also decreased the late (inflammatory) phase of formalin-induced licking, without affecting responses of the first (neurogenic) phase. In a different set of experiments, AR-A014418 (.1-10 μg/site) coinjected intraplantarly (ipl) with formalin inhibited the late phase of formalin-induced nociception. Furthermore, AR-A014418 administration (1 and 10 ng/site, intrathecal [it]) inhibited both phases of formalin-induced licking. In addition, AR-A014418 coinjection (10 ng/site, it) inhibited nociception induced by glutamate, N-methyl-D-aspartate (NMDA), (±)-1-aminocyclopentane-trans-1,3-dicarboxylic acid (trans-ACPD), tumor necrosis factor-alpha (TNF-α), and interleukin-1beta (IL-1β) by 47 ± 12%, 48 ± 11%, 31 ± 8%, 46 ± 13%, and 44 ± 11%, respectively. In addition, a 30-minute pretreatment with NP031115 (3 and 10 mg/kg, ip), a different GSK-3 β inhibitor, also attenuated the late phase of formalin-induced nociception. Collectively, these results provide convincing evidence that AR-A014418, given by local, systemic, and central routes, produces antinociception in several mouse models of nociception. The AR-A014418-dependent antinociceptive effects were induced by modulation of the glutamatergic system through metabotropic and ionotropic (NMDA) receptors and the inhibition of the cytokine (TNF-α and IL-1β) signaling.

PERSPECTIVE

These results suggest that GSK-3β may be a novel pharmacological target for the treatment of pain.

Haeme oxygenase-1 overexpression via nAChRs and the transcription factor Nrf2 has antinociceptive effects in the formalin test

Epibatidine has shown antinociceptive effects in various pain models, being 200-fold more potent than morphine. Previous results from our laboratory demonstrated that HO-1 overexpression has an antinociceptive effect in the formalin test. Furthermore, epibatidine was able to induce haeme oxygenase-1 (HO-1). So, the aim of this study was to investigate the effect of HO-1 overexpression induced by epibatidine in nociception elicited by formalin injection in the mice hindpaw. Administration of epibatidine (4 microg/kg) 24h before the test reduced the nociceptive response during the first phase and second phase of the formalin test. This effect was prevented by treatment with tin protoporphyrin (SnPP, an inhibitor of HO-1 activity) administered via intraplantar 5min before the test, suggesting a main role of HO-1. Western blot analysis revealed that epibatidine treatment increased by 2-fold HO-1 expression in the paw; this effect was lost in knockout mice for nuclear factor-erythroid 2-related factor 2 (Nrf2) and was accompanied by the loss of its antinociceptive effect. Furthermore, the antinociceptive effect of epibatidine was related to the activation of alpha7 and/or alpha9 nAChRs since methyllycaconitine (MLA) and mecamylamine but not dihydro-beta-erythroidine (DHbetaE) reverted this effect. Finally, we showed by flow cytometry and by immunofluorescence that white blood cells of the animals injected with epibatidine expressed more HO-1 than control animals, and this expression was also reverted by MLA pre-treatment. These findings demonstrate that HO-1 induction by epibatidine has antinociceptive and anti-inflammatory effects by the activation of MLA-sensitive nAChRs.

Ascorbic acid administration produces an antidepressant-like effect: evidence for the involvement of monoaminergic neurotransmission

Ascorbic acid is highly concentrated in the brain, being considered as a neuromodulator. This study investigated the effect of ascorbic acid in the tail suspension test (TST) and in the forced swimming test (FST) in mice and the contribution of the monoaminergic system to its antidepressant-like effect. Moreover, the effects of fluoxetine, imipramine and bupropion in combination with ascorbic acid in the TST were investigated. Ascorbic acid (0.1-10 mg/kg, i.p., 1-10 mg/kg p.o. or 0.1 nmol/mice i.c.v.) produced an antidepressant-like effect in the TST, but not in the FST, without altering the locomotor activity. The effect of ascorbic acid (0.1 mg/kg, i.p.) in the TST was prevented by i.p. pre-treatment with NAN-190 (0.5 mg/kg), ketanserin (5 mg/kg), MDL72222 (0.1 mg/kg), prazosin (62.5 microg/kg), yohimbine (1 mg/kg), propranolol (2 mg/kg), haloperidol (0.2 mg/kg), sulpiride (50 mg/kg), but not with SCH23390 (0.05 mg/kg, s.c.). Additionally, ascorbic acid (1 mg/kg, p.o.) potentiated the effect of subeffective doses (p.o. route) of fluoxetine (1 mg/kg), imipramine (0.1 mg/kg), or bupropion (1 mg/kg) in the TST. The combined treatment of ascorbic acid with antidepressants produced no alteration in the locomotion in the open-field test. In conclusion, our results show that administration of ascorbic acid produces an antidepressant-like effect in TST, which is dependent on its interaction with the monoaminergic system. Moreover, ascorbic acid caused a synergistic antidepressant-like effect with conventional antidepressants. Therefore, the present findings warrant further studies to evaluate the therapeutical relevance of ascorbic acid for the treatment of depression and as a co-adjuvant treatment with antidepressants.

Spinal mechanisms of antinociceptive action caused by diphenyl diselenide

The present study was designed to investigate further the mechanisms involved in the antinociception caused by diphenyl diselenide in behavioral model of pain in mice. Diphenyl diselenide (1-100 mg/kg), given orally, produced significant inhibition of the biting behavior induced by intrathecal (i.t.) injection of glutamate (175 nmol/site) and N-methyl-d-aspartate (NMDA; 450 pmol/site), with mean ID(50) values of 45.92 (39.74-60.4) and 55.77 (36.52-77.5) mg/kg respectively. However, diphenyl diselenide completely failed to affect the nociception induced by alpha-amino-3-hydroxy-5-mehtyl-4-isoxazolepropionic acid (AMPA; 135 pmol/site), (+/-)-1-aminocyclopentane-trans-1,3-dicarboxylic acid (trans-ACPD; 50 nmol/site) and kainate (110 pmol/site). This compound also reduced the nociceptive response induced by substance P (SP) (135 ng/site, i.t.), interleukin 1beta (IL-1beta; 1 pg/site), tumor necrosis factor-alpha (TNF-alpha; 0.1 pg/site), bradykinin (BK; 0.1 microg/site) and capsaicin (30 ng/site) with mean ID(50) values of 16.22, 7.06, 6.06, 4.18 and 7.90 mg/kg, respectively. Together, these results indicate that diphenyl diselenide produced antinociception at spinal sites, with a possible interaction with glutamatergic pathways, more specifically via interaction with NMDA receptors, peptidergic or vanilloid systems.

Effect of drug-induced ascorbic acid release in the striatum and the nucleus accumbens in hippocampus-lesioned rats

The mechanism of ethanol, morphine, methamphetamine (MAP), and nicotine-induced ascorbic acid (AA) release in striatum, and nucleus accumbens (NAc) is not well understood. Our previous study showed that the glutamatergic system was involved in the addictive drug-induced AA release in NAc and striatum. Furthermore, frontal decortication eliminates drug-induced ascorbic acid release in the striatum but not in the NAc. In the present study, the roles of the hippocampus in drug-induced AA release in the striatum and NAc were studied by using microdialysis coupled to high performance liquid chromatography with electrochemical detection (HPLC-ECD). Ethanol (3.0 g/kg, i.p.), methamphetamine (3.0 mg/kg, i.p.), and nicotine (1.5 mg/kg, i.p.) significantly stimulated AA release in the striatum and NAc, respectively. Morphine (20 mg/kg, i.p.) significantly stimulated AA release in the striatum, but not in the NAc. After hippocampal lesion by kainic acid, AA release induced by ethanol, methamphetamine, and nicotine could be eliminated in NAc, but not in the striatum. These results suggest that the hippocampus might be a common and necessary area in addictive drug-induced AA release in the NAc, which also imply that different pathways might be involved in drug-induced AA release in the striatum and the NAc of the rats.