Electroneuromyographic studies of pain sensitivity

We analyze the published information on the techniques of studies of pain sensitivity using objective electroneuromyographic approaches and the results of these studies. In particular, we describe works where the H reflex, nociceptive flexor and blinking reflexes, and exteroceptive suppression of voluntary muscle activity were examined. Some aspects of using somatosensory evoked potentials in the studies of pain phenomena are also discussed.     

Functional Activity of the Sympathoadrenal System and Behavioral Indices of Rats: Changes Induced by Millimeter-Range Electromagnetic Radiation

We examined the ability of low-intensity millimeter-range (mmR) electromagnetic radiation (EMR) to modify the functional activity of the sympathoadrenal system (SAS) and the behavioral reactions in intact rats and rats with an experimentally induced stress reaction. Adaptation of the organism to mmR EMR has been shown to limit SAS activation; this is considered one of the mechanisms of the antistressor effect of such radiation.     

Erratum to: The original online version of the following articles was revised: the issue date is not January 2020, but January 2021

Journal of Evolutionary Biochemistry and Physiology - A Correction to this paper has been published: https://doi.org/10.1134/S0022093021020216     

Efficacy of faecal microbiota transplantation in Crohn’s disease: a new target treatment?

The efficacy of faecal microbiota transplantation (FMT) in Crohn’s disease (CD) remains unclear due to lack of data. This study aimed to assess the value of FMT in treating CD-related clinical targets. The use of FMT for CD as a registered trial (NCT01793831) was performed between October 2012 and December 2017. Seven therapeutic targets included abdominal pain, diarrhoea, hematochezia, fever, steroid-dependence, enterocutaneous fistula and active perianal fistula. Each target was recorded as 1 (yes) or 0 (no) during the long-term follow-up for each patient. The primary outcome was the rate of improvement in each therapeutic target. Overall, 174 patients completed the follow-up. The median follow-up duration was 43 (interquartile range, 28–59) months. The median score of the total targets was 2 (range, 1–4) before FMT, and it decreased significantly at 1, 3, 6, 12, 24 and 36 months after FMT (P < 0.001 respectively). At 1 month after FMT, 72.7% (101/139), 61.6% (90/146), 76% (19/25) and 70.6% (12/17) of patients achieved improvement in abdominal pain, diarrhoea, hematochezia and fever respectively. Furthermore, 50% (10/20) of steroid-dependent patients achieved steroid-free remission after FMT. The present findings indicate that it is important to understand the efficacy of FMT in CD as a targeted therapy, especially for abdominal pain, hematochezia, fever and diarrhoea.     

Type 1 corticotropin-releasing factor receptors in the ventromedial hypothalamus promote hypoglycemia-induced hormonal counterregulation

Type 2 corticotropin-releasing factor (CRF) receptors (CRFR2) within the ventromedial hypothalamus (VMH), a key glucose-sensing region, play a major role in regulating the hormonal counterregulatory responses (CRRs) to acute hypoglycemia. The VMH expresses both subtypes of CRF receptors, CRFR1 and CRFR2. The objective of this study was to examine the role of the CRFR1 receptor in the VMH in the regulation of the CRR to acute hypoglycemia. To compare the hormonal CRR to hypoglycemia, awake and unrestrained Sprague-Dawley rats were bilaterally microinjected to the VMH with either 1) aECF, 2) CRF (1 pmol/side), 3) CRFR1 antagonist Antalarmin (500 pmol/side), or 4) CRF + Antalarmin prior to undergoing a hyperinsulinemic hypoglycemic (2.8 mM) clamp. A second series of studies also incorporated an infusion of [(3)H]glucose to allow the calculation of glucose dynamics. In addition the effect of CRFR1 antagonism in the paraventricular nucleus (PVN) was studied. Activation of VMH CRFR1 increased, whereas inhibition of CRFR1 suppressed hypoglycemia-induced CRRs. Inhibition of VMH CRFR1 also increased peripheral glucose utilization and reduced endogenous glucose production during hypoglycemia, whereas VMH CRF reduced peripheral glucose utilization. In contrast CRFR1 inhibition in the PVN blunted corticosterone but not epinephrine or glucagon CRR to hypoglycemia. In contrast to CRFR2 activation, CRFR1 activation within the VMH amplifies CRRs to acute hypoglycemia. The balance between these two opposing CRFRs in this key glucose-sensing region may play an important role in determining the magnitude of CRRs to acute hypoglycemia.     

The Effects of Low-Intensity Millimeter-Wavelength Radiation and Electromagnetic Shielding on Pain Sensitivity in Rats

Here, we studied changes in pain sensitivity in rats subjected to low-intensity millimeter-wavelength electromagnetic radiation (EMR MM) of 7.1 mm and 0.1 mW/cm² in the occipital-collar region with daily exposure of 30 min over 21 days. As well, this radiation was combined with moderate electromagnetic shielding (EMS) which had the following parameters. The shielding coefficients of the constant component of the magnetic field along the vertical and horizontal constituents were 4.4- and 20-fold, respectively, with an exposure of 22 h/day over 21 days. The pain sensitivity was estimated with algometric tests, that is, the hot plate, flick-tail, and algesimeter-pincher tests; these allowed observation of the pain impulse at different regulatory levels. The algological effects of both individual and combined EMR MM and EMS were demonstrated. It was shown that EMR MM has an antinociceptive property when combined with EMS, as well as a modulation effect caused by shielding during hyperalgesia. At the same time, shielding reduces the antinociceptive effect of EMR MM.

     

Antinociceptive effects of low-intensity extrahigh-frequency electromagnetic radiation

We studied the effect of low-intensity extrahigh-frequency (EHF) electromagnetic radiation (EMR) on changes of behavior phenomena in rats observed under conditions of experimentally induced tonic somatic, visceral, and acute thermal pain. Preliminary irradiation of the animals with EHF EMR was found to exert clear antinociceptive effects. Decreases in the intensity of pain reactions were observed under conditions of both single and repeated irradiation sessions. Neirofiziologiya/Neurophysiology, Vol. 38, No. 4, pp. 331–341, July–August, 2006.     

Interhemisphere Asymmetry of the Pro-/Antioxidant Systems in the Rat Brain: Effects of Hypokinesia and Extrahigh-Frequency Electromagnetic Radiation

We studied changes in the interhemisphere asymmetry of the intensity of lipid peroxidation (LPO) and total content of thiol groups (TTG) in the rat cerebral neocortex. These indices characteristic for animals with different motor phenotypes (dextrals, sinistrals, and ambidextrals) were measured in the control and under the influence of hypokinesia, low-intensity millimeter-range electromagnetic radiation (mmR EMR), and their combination. The development of hypokinetic stress in rats (after 10-day-long motor restriction) resulted in a sharp activation of LPO and suppression of thiol/disulfide metabolism in the neocortex of rats with different types of motor asymmetry. Hypokinesia was accompanied by considerable drops in the coefficients of interhemisphere asymmetry (up to reversal of their signs); this can be related to decreases in the resistivity of the organism to stress and adaptability to external influences. When intact animals with different types of motor asymmetry were irradiated with mmR EMR, the intensity of LPO in the neocortex of both hemispheres decreased concurrently with intensification of thiol/ disulfide metabolism. The combined influence of hypokinesia and mmR EMR led to considerably smaller shifts in the above indices, as compared with those after isolated action of hypokinesia. When mmR EMR influenced animals were kept under conditions of normal motor mode and motor restriction, the signs of the coefficients of asymmetry of the indices under study did not change, while the intensity of interhemisphere asymmetry increased. We suppose that this is related to an increase in the adaptability of the organism to the action of stressor factors.     

Biodegradation of Chlorpyrifos and Its Hydrolysis Product 3,5,6-Trichloro-2-Pyridinol by a New Fungal Strain Cladosporium cladosporioides Hu-01

Intensive use of chlorpyrifos has resulted in its ubiquitous presence as a contaminant in surface streams and soils. It is thus critically essential to develop bioremediation methods to degrade and eliminate this pollutant from environments. We present here that a new fungal strain Hu-01 with high chlorpyrifos-degradation activity was isolated and identified as Cladosporium cladosporioides based on the morphology and 5.8S rDNA gene analysis. Strain Hu-01 utilized 50 mg·L⁻¹ of chlorpyrifos as the sole carbon of source, and tolerated high concentration of chlorpyrifos up to 500 mg·L⁻¹. The optimum degradation conditions were determined to be 26.8°C and pH 6.5 based on the response surface methodology (RSM). Under these conditions, strain Hu-01 completely metabolized the supplemented chlorpyrifos (50 mg·L⁻¹) within 5 d. During the biodegradation process, transient accumulation of 3,5,6-trichloro-2-pyridinol (TCP) was observed. However, this intermediate product did not accumulate in the medium and disappeared quickly. No persistent accumulative metabolite was detected by gas chromatopraphy-mass spectrometry (GC-MS) analysis at the end of experiment. Furthermore, degradation kinetics of chlorpyrifos and TCP followed the first-order model. Compared to the non-inoculated controls, the half-lives (t _1/2) of chlorpyrifos and TCP significantly reduced by 688.0 and 986.9 h with the inoculum, respectively. The isolate harbors the metabolic pathway for the complete detoxification of chlorpyrifos and its hydrolysis product TCP, thus suggesting the fungus may be a promising candidate for bioremediation of chlorpyrifos-contaminated water, soil or crop.