Desensitization of menthol-activated cold receptors in lower extremities during local cooling in young women with a cold constitution

Effects of a Standardized Oligomerized-Polyphenol from Litchi chinensis Fruit Extract and Mixed Plant Extract Supplementation on Peripheral Circulation and Cold Sensitivity

Certain individuals tend to suffer from a cold sensation-particularly in the lower extremities-despite most people not suffering from the same sensation. In Japan, this phenomenon is called "hie-sho" and reduces quality of life for several people, particularly women. A previous study has shown that a standardized oligomerized-polyphenol from Litchi chinensis fruit extract (OPLFE) reportedly causes a significant increase in body surface temperature. The present study aimed to investigate whether supplementation with OPLFE affected peripheral circulation and cold sensitivity. This randomized, double-blind, placebo-controlled trial was performed including 25 participants (age, 45.0±10.4 y; 3 males and 22 females) who were assigned to consume OPLFE, mixed plant extract with OPLFE, or placebo capsules for 14 d. Participants were instructed to relax for 60 min in a temperature-controlled room prior to obtaining measurements. Changes in skin temperature and peripheral blood flow of the middle finger were assessed immediately before and 1, 5, 10, 20, and 30 min after immersion in cold water (10ºC). Participants' height, weight, skin temperature, and blood flow in peripheral tissue were measured; furthermore, their "hie-sho" was measured using the Visual Analog Scale (VAS). Skin temperature and blood flow in peripheral tissue increased in the OPLFE and mixed plant extract with OPLFE groups on day 14 compared with those on day 1. In addition, cold sensitivity in these two groups significantly improved between day 1 and day 14. These findings suggest that OPLFE improves "hie-sho" by increasing peripheral blood flow and skin temperature.

Effect of the menstrual cycle phase on foot skin temperature during menthol application in young women

According to the literature, the arteriovenous anastomoses in the peripheral parts (ex. hands and feet) respond thermal stimulation susceptibly. Thus, the feet are sensitive to cold stimulation. The aim of the present study was to investigate the effect of menstrual cycle on skin temperature (T_sk) of the foot during menthol application in young women. T_sk and partial cutaneous blood flow in the foot, tympanic temperature, blood pressure, heart rate, thermal sensation and pleasantness during the preovulatory (P), luteal (L), and menstrual (M) phases during menthol application in young women using thermography, laser Doppler flowmetry, a digital blood pressure monitor, and VAS scale were examined at 25 °C. After application of the 0.5% menthol solution to the right foot, the measurements were continued for 20 min. The T_sk of the second and third right toes in the P phase were lower than that in the L phase. The T_sk of the little right toe in the P phase was lower than that in the L and M phases. No significant differences were observed in the T_sk of the dorsum of right foot, cutaneous Laser-Doppler flow in the right great toe, tympanic temperature, blood pressure, heart rate, thermal sensation and pleasantness among the phases. The menstrual cycle phase did not affect T_sk in the dorsum of the foot, but it affected T_sk in some toes during menthol application.

Hepatotoxicity of Herbal Supplements Mediated by Modulation of Cytochrome P450

Herbal supplements are a significant source of drug-drug interactions (DDIs), herb-drug interactions, and hepatotoxicity. Cytochrome P450 (CYP450) enzymes metabolize a large number of FDA-approved pharmaceuticals and herbal supplements. This metabolism of pharmaceuticals and supplements can be augmented by concomitant use of either pharmaceuticals or supplements. The xenobiotic receptors constitutive androstane receptor (CAR) and the pregnane X receptor (PXR) can respond to xenobiotics by increasing the expression of a large number of genes that are involved in the metabolism of xenobiotics, including CYP450s. Conversely, but not exclusively, many xenobiotics can inhibit the activity of CYP450s. Induction of the expression or inhibition of the activity of CYP450s can result in DDIs and toxicity. Currently, the United States (US) Food and Drug Administration does not require the investigation of the interactions of herbal supplements and CYP450s. This review provides a summary of herbal supplements that inhibit CYP450s, induce the expression of CYP450s, and/or whose toxicity is mediated by CYP450s.

Body temperature and cold sensation during and following exercise under temperate room conditions in cold-sensitive young trained females

We evaluated cold sensation at rest and in response to exercise-induced changes in core and skin temperatures in cold-sensitive exercise trained females. Fifty-eight trained young females were screened by a questionnaire, selecting cold-sensitive (Cold-sensitive, n = 7) and non-cold-sensitive (Control, n = 7) individuals. Participants rested in a room at 29.5°C for ~100 min after which ambient temperature was reduced to 23.5°C where they remained resting for 60 min. Participants then performed 30-min of moderate intensity cycling (50% peak oxygen uptake) followed by a 60-min recovery. Core and mean skin temperatures and cold sensation over the whole-body and extremities (fingers and toes) were assessed throughout. Resting core temperature was lower in the Cold-sensitive relative to Control group (36.4 ± 0.3 vs. 36.7 ± 0.2°C). Core temperature increased to similar levels at end-exercise (~37.2°C) and gradually returned to near preexercise rest levels at the end of recovery (>36.6°C). Whole-body cold sensation was greater in the Cold-sensitive relative to Control group during resting at a room temperature of 23.5°C only without a difference in mean skin temperature between groups. In contrast, cold sensation of the extremities was greater in the Cold-sensitive group prior to, during and following exercise albeit this was not paralleled by differences in mean extremity skin temperature. We show that young trained females who are sensitive to cold exhibit augmented whole-body cold sensation during rest under temperate ambient conditions. However, this response is diminished during and following exercise. In contrast, cold sensation of extremities is augmented during resting that persists during and following exercise.