Ascorbic acid augments the adenylyl cyclase-cAMP system mediated POMC mRNA expression and beta-endorphin secretion from hypothalamic neurons in culture

Low Trend for VZV-Associated Disease Patients to Visit Neurologists

Background

Herpes zoster (HZ) is a skin disease that can also cause virus-infectious peripheral neuropathies. Despite this, there is limited information on patient preferences for seeking medical attention for HZ and zoster-associated pain (ZAP). Our study aimed to evaluate how frequently patients with ZAP choose to visit neurologists for their symptoms.

Methods

This study conducted a retrospective review of electronic health records in three general hospitals from January 2017 to June 2022. Using association rule mining, the study analyzed referral behaviors.

Results

We identified 33,633 patients with 111,488 outpatient visits over 5.5 years. The study found that the majority of patients (74.77-91.22%) visited dermatologists during their first outpatient visit, while only a small percentage (0.86-1.47%) preferred to consult a neurologist. The proportion of patients referred to a specialist during their medical visit varied significantly between different specialties within the same hospital (p <0.05) and even within the same specialty (p<0.05). There was a weak association (Lift:1.00-1.17) of referral behaviors between dermatology and neurology. Across the three hospitals, the average number of visits to a neurologist for ZAP was 1.42-2.49, with an average electronic health record duration of 11-15 days per patient. After consulting with a neurologist, some patients were referred to other specialists.

Conclusion

It was observed that patients with HZ and ZAP tended to visit a variety of specialists, with only a small number seeking the assistance of neurologists. However, from the perspective of neuroprotection, it is the duty of neurologists to provide more means.

Plasma Vitamin C Concentrations Were Negatively Associated with Tingling, Prickling or Pins and Needles Sensation in Patients with Postherpetic Neuralgia

Vitamin C deficiency increases the risk of postherpetic neuralgia (PHN). In this cross-sectional study, the relationships among plasma vitamin C concentrations, pain and Leeds assessment of neuropathic symptoms and signs (LANSS) items were investigated during their first pain clinic visit of 120 PHN patients. The factors associated with vitamin C deficiency were determined. Independent predictors of vitamin C deficiency were presented as adjusted odds ratios (AOR) and 95% confidence intervals (CI). The patients had a high prevalence (52.5%) of vitamin C deficiency. Their plasma vitamin C concentrations were negatively associated with spontaneous pain and tingling, prickling or pins and needles sensation according to the LANSS questionnaire. Based on the receiver operator characteristic curve, the cutoffs for plasma vitamin C to predict moderate-to-severe and severe symptoms of sharp sensation were <7.05 and <5.68 mg/L, respectively. By comparison, the patients well-nourished with vitamin C had lower incidences of sharp sensations, sharp pain, and reddish skin. Multivariate analyses revealed that vitamin C deficiency was associated with the low intake of fruit/vegetables (AOR 2.66, 95% CI 1.09–6.48, p = 0.032), peptic ulcer disease (AOR 3.25, 95% CI 1.28–8.28, p = 0.014), and smoking (AOR 3.60, 95% CI 1.33–9.77, p = 0.010). Future studies are needed to substantiate these findings.

Neurobiology of vitamin C: Expanding the focus from antioxidant to endogenous neuromodulator

Ascorbic acid (AA) is a water-soluble vitamin (C) found in all bodily organs. Most mammals synthesize it, humans are required to eat it, but all mammals need it for healthy functioning. AA reaches its highest concentration in the brain where both neurons and glia rely on tightly regulated uptake from blood via the glucose transport system and sodium-coupled active transport to accumulate and maintain AA at millimolar levels. As a prototype antioxidant, AA is not only neuroprotective, but also functions as a cofactor in redox-coupled reactions essential for the synthesis of neurotransmitters (e.g., dopamine and norepinephrine) and paracrine lipid mediators (e.g., epoxiecoisatrienoic acids) as well as the epigenetic regulation of DNA. Although redox capacity led to the promotion of AA in high doses as potential treatment for various neuropathological and psychiatric conditions, ample evidence has not supported this therapeutic strategy. Here, we focus on some long-neglected aspects of AA neurobiology, including its modulatory role in synaptic transmission as demonstrated by the long-established link between release of endogenous AA in brain extracellular fluid and the clearance of glutamate, an excitatory amino acid. Evidence that this link can be disrupted in animal models of Huntington´s disease is revealing opportunities for new research pathways and therapeutic applications (e.g., epilepsy and pain management). In fact, we suggest that improved understanding of the regulation of endogenous AA and its interaction with key brain neurotransmitter systems, rather than administration of AA in excess, should be the target of future brain-based therapies.

Intracellular ascorbate tightens the endothelial permeability barrier through Epac1 and the tubulin cytoskeleton

Vitamin C, or ascorbic acid, both tightens the endothelial permeability barrier in basal cells and also prevents barrier leak induced by inflammatory agents. Barrier tightening by ascorbate in basal endothelial cells requires nitric oxide derived from activation of nitric oxide synthase. Although ascorbate did not affect cyclic AMP levels in our previous study, there remains a question of whether it might activate downstream cyclic AMP-dependent pathways. In this work, we found in both primary and immortalized cultured endothelial cells that ascorbate tightened the endothelial permeability barrier by ∼30%. In human umbilical vein endothelial cells, this occurred at what are likely physiologic intracellular ascorbate concentrations. In so doing, ascorbate decreased measures of oxidative stress and also flattened the cells to increase cell-to-cell contact. Inhibition of downstream cyclic AMP-dependent proteins via protein kinase A did not prevent ascorbate from tightening the endothelial permeability barrier, whereas inhibition of Epac1 did block the ascorbate effect. Although Epac1 was required, its mediator Rap1 was not activated. Furthermore, ascorbate acutely stabilized microtubules during depolymerization induced by colchicine and nocodazole. Over several days in culture, ascorbate also increased the amount of stable acetylated α-tubulin. Microtubule stabilization was further suggested by the finding that ascorbate increased the amount of Epac1 bound to α-tubulin. These results suggest that physiologic ascorbate concentrations tighten the endothelial permeability barrier in unstimulated cells by stabilizing microtubules in a manner downstream of cyclic AMP that might be due both to increasing nitric oxide availability and to scavenging of reactive oxygen or nitrogen species.

Antioxidant and anti-nociceptive effects of Phyllanthus amarus on improving exercise recovery in sedentary men: a randomized crossover (double-blind) design

BACKGROUND

Phyllanthus amarus (PA) is a herbal plant containing antioxidant compounds that scavenge free radicals. The reduced oxidative stress may decrease muscle damage leading to early recovery from muscle soreness. This study aimed to evaluate the effects of PA powder on oxidative stress, muscle damage, leukocyte counts, inflammation, and muscle soreness after a single bout of high-intensity exercise.

METHODS

Twelve men participated in two 3-day phases separated by a 1-week washout in a randomized double-blinded, crossover design. On day 1, randomly divided participants ingested two capsules of either PA (PA group) or placebo (PLA group) 20 min before a single bout of cycling at high intensity for 20 min followed by four capsules (two capsules after lunch and dinner), and six capsules/day for the next 2 days. Blood samples were collected before, immediately after, and 24 and 48 h after the exercise. Pain threshold was measured at the mid-thigh on both legs.

RESULTS

Malondialdehyde concentration in the PA group was lower than that in the PLA group (p < 0.05) 48 h after high-intensity exercise. Vitamin C concentration was greater in the PA than in the PLA group (p < 0.05) immediately after high-intensity exercise. Pain threshold in both legs in the PA group was higher than in the PLA group 24 and 48 h after high-intensity exercise. There were no significant differences in creatine kinase, leukocyte counts or inflammation between groups.

CONCLUSION

Acute PA supplementation reduced oxidative stress and muscle soreness induced by high-intensity exercise.

NXCL-4950, a novel composite applicable to peripheral skin, is capable of increasing skin temperature by enhancing capillary circulation

BACKGROUND

Rapid skin warming and prompt correct medical treatment lead to dramatic improvement in patients with peripheral capillary-related damage, such as injuries, Raynaud disease and frostbite.

AIM

To characterize a novel composite, NXCL-4950, for use in a cosmetic lotion.

METHODS

The effects of NXCL-4950 on enhancing skin blood flow, skin temperature warming, and expansion of peripheral blood vessels and scalp microvessels were investigated.

RESULTS

Monitoring by laser Doppler perfusion imaging and thermal imaging showed that application of NXCL-4950 to the hands increased skin blood flow and temperature relative to the control (or placebo) group. For the 20 participants with a high Raynaud Condition Score, application of NXCL-4950 to the skin resulted in a mean increase of 215.53% in microvessel diameter and mean increase of 164.96% in the speed of blood flow. When NXCL-4950 was applied to the scalp, the microvessels around the hair roots were clearly visible after 20 min.

CONCLUSION

NXCL-4950 is a potential candidate for enhancing peripheral skin temperature, and might be useful in the treatment of capillary-related disorders.

Characterization of metabolic phenotypes of mice lacking GPR61, an orphan G-protein coupled receptor

AIMS

GPR61 is an orphan G protein-coupled receptor whose function remains unknown. The purpose of the present study is to elucidate the importance of GPR61 in metabolism by characterization of GPR61-deficient mice.

MAIN METHODS

Male GPR61-deficient mice were characterized regarding various metabolic parameters, including food intake, body weight, oxygen consumption, body temperature, locomotor activity, and in a pair feeding study. Hypothalamic gene expression was analyzed using real-time quantitative RT-PCR.

KEY FINDINGS

GPR61-deficient mice exhibited marked hyperphagia and heavier body weight than wild-type mice. Hyperphagia of GPR61-deficient mice was observed before the differences in body weight became apparent between the genotypes. When body weight difference did become apparent between genotypes, increases in visceral fat pad weight, liver weight, liver triglyceride (TG) content, plasma leptin, and plasma insulin were observed in GPR61-deficient mice, suggesting that GPR61 deficiency caused obesity associated with hyperphagia. Oxygen consumption, body temperature, and locomotor activity were not significantly different between GPR61-deficient and wild-type mice. Pair-fed GPR61-deficient mice had a greater fat mass than wild-type mice despite comparable body weight in both genotypes. The mRNA levels of proopiomelanocortin (POMC) and brain-derived neurotropic factor (BDNF) in the hypothalamus of GPR61-deficient mice were significantly lower than those of wild-type mice.

SIGNIFICANCE

GPR61-deficient mice exhibited obesity associated with hyperphagia. These findings suggest that GPR61 is involved in the regulation of food intake and body weight, and may be of importance when considering GPR61 as a therapeutic target for obesity or eating disorders.

Plasma vitamin C is lower in postherpetic neuralgia patients and administration of vitamin C reduces spontaneous pain but not brush-evoked pain

OBJECTIVES

Plasma vitamin C concentrations have been suggested to be related to pain modulation in postherpetic neuralgia (PHN), an intractable neuropathic pain syndrome. In this study, we first compared plasma concentrations of vitamin C between healthy volunteers and PHN patients and then designed a symptom-based and mechanism-based approach to assess the analgesic effect of intravenous vitamin C on spontaneous and brush-evoked pain.

METHODS

Study 1 was cross-sectional that enrolled 39 healthy volunteers and 38 PHN patients. Study 2 was a double-blinded, placebo-controlled intervention study, which comprised 41 patients randomly allocated into the ascorbate group and placebo. Each patient received normal saline infusion with or without ascorbate on days 1, 3, and 5 and answered questionnaires that included side effects; numeric rating pain scale (NRS) on spontaneous and brush-evoked pain on days 1, 3, 5, and 7; and patient global impression of change on spontaneous and brush-evoked pain on day 7.

RESULTS

Study 1 revealed that plasma concentrations of vitamin C were significantly lower in patients with PHN than in healthy volunteers (P<0.001). Study 2 showed that ascorbate treatment effectively restored plasma vitamin C concentrations in the patients and decreased spontaneous pain by 3.1 in NRS from baseline to day 7, as compared with a decrease of 0.85 in NRS by placebo treatment (P<0.001). Conversely, ascorbate treatment did not significantly affect brush-evoked pain. Ascorbate treatment also resulted in a better efficacy than placebo in patient global impression of change on spontaneous pain (P<0.001) on day 7 and did not affect brush-evoked pain. No side effects were observed.

CONCLUSIONS

Plasma vitamin C status plays a role in PHN, and intravenous ascorbate helps relieve spontaneous pain in PHN.

Ascorbic acid does not influence consciousness recovery after anesthesia

Several studies have examined the influence of general anesthesia on changes in consciousness and unconscious cognitive processes. However, much remains to be learned about potential moderators of general anesthetic agents, such as antioxidants including ascorbic acid, and their influence on the recovery of consciousness following general anesthesia. General anesthesia potentially affects plasma ascorbic acid levels and may impair consciousness during the postoperative period; however, published literature regarding these relationships is equivocal. Ascorbic acid is important for brain function and may be related to the return of postoperative consciousness through action on the synaptic receptors in the brain. This study was designed as a pretest-posttest repeated measures investigation. Ascorbic acid levels were measured at four time periods in patients (N = 50) undergoing surgery and general anesthesia. Following surgery, patients were administered a paper-and-pencil measure of concentration that served as an index of post-anesthesia consciousness. The results suggest that changes occur in plasma ascorbic acid levels at different time points during the anesthesia regimen in nonemergent surgical patients. No statistically significant relationships were found between plasma ascorbic acid levels and improved post-anesthesia consciousness, suggesting that ascorbic acid does not influence recovery of consciousness following general anesthesia.

Ascorbic acid treatment corrects the phenotype of a mouse model of Charcot-Marie-Tooth disease

Charcot-Marie-Tooth disease (CMT) is the most common hereditary peripheral neuropathy, affecting 1 in 2,500 people. The only treatment currently available is rehabilitation or corrective surgery. The most frequent form of the disease, CMT-1A, involves abnormal myelination of the peripheral nerves. Here we used a mouse model of CMT-1A to test the ability of ascorbic acid, a known promoter of myelination, to correct the CMT-1A phenotype. Ascorbic acid treatment resulted in substantial amelioration of the CMT-1A phenotype, and reduced the expression of PMP22 to a level below what is necessary to induce the disease phenotype. As ascorbic acid has already been approved by the FDA for other clinical indications, it offers an immediate therapeutic possibility for patients with the disease.