Methyl Jasmonate-Induced Stimulation of Sarcoplasmic Reticulum Ca 2ϩ -ATPase Affects Contractile Responses in Rat Slow-Twitch Skeletal Muscle

ABSTRACT The purpose of this study was to determine whether methyl jasmonate, a stimulator of Ca 2ϩ -adenosine triphosphatase (ATPase) activity of the purified ATPase from fast-twitch skeletal muscle, could affect contractile responses in small bundles of rat isolated slow-twitch (soleus) fibers. In saponin-skinned fibers, sarcoplasmic reticulum (SR) Ca 2ϩ loading was performed in pCa 7.0 solution. The amount of Ca 2ϩ taken up was monitored by use of the amplitude of contraction following application of 10 mM caffeine. Results indicate that the increased loading rate in the presence of methyl jasmonate is likely due to stimulation of the SR Ca 2ϩ -ATPase. In Triton-skinned fibers, the myofibrillar Ca 2ϩ sensitivity was not changed by methyl jasmonate (50 -200 M). In intact fibers, the amplitude and the time constant of relaxation of twitch and potassium contracture were reversibly reduced after 2 min of application of methyl jasmonate at a concentration of up to 125 M. At higher concentrations (Ͼ150 M), effects were not reversible. In the presence of methyl jasmonate (100 M), the relationship between the amplitude of potassium contractures and the membrane potential shifted to more positive potentials, whereas the steady-state inactivation curve was unchanged. These observations suggest that methyl jasmonate has no effect on voltage sensors. Taken together, our results show that methyl jasmonate is a potent, reversible, and specific stimulator of the SR Ca 2ϩ pump in slow-twitch skeletal muscle and is an extremely valuable pharmacological tool for improving relaxation and studying calcium-signaling questions

Impact of GSM-EMW exposure on the markers of oxidative stress in fetal rat liver

Abstract The current study investigated the effects of 24 h/day prenatal exposure to global system for mobile communication electromagnetic fields (GSM-EMFs), 900 MHZ-induced electromagnetic radiation (EMR), on oxidative stress (OS) status, apoptotic, and inflammatory changes in liver of rats during their fetal development period. Fifty-two Sprague–Dawley pregnant rats were equally divided into control and exposed groups. Whole embryos were removed at 7.5 dpc (days post coitus), while liver tissues were extracted from embryos at 11.5, 15.5, and 19.5 dpc. For exposed animals, results showed an increased OS reflected by high levels of malondialdehyde (MDA), a decrease in cytosolic superoxide dismutase (cytoSOD) activity, in mitochondrial superoxide dismutase (mitoSOD) levels and catalase (CAT) mRNA expression but also in hepatic nuclear factor erythroïd 2-related Factor 2 (Nrf-2), protein kinase B (Akt1), and intercellular adhesion molecule-1 (ICAM-1) mRNA expression at 15.5 dpc. Moreover, GSM-EMR exposure was shown to significantly decrease mitoSOD and CAT activities at almost all studied ages. Thus, rat embryos may be protected by their mothers from OS, apoptotic, and pro-inflammatory responses till a sensitive developmental stage, during a continuous prenatal EMR exposure. This protection could be then created from the embryos themselves

Effects of chlorpyrifos exposure during development on the contractility of longitudinal smooth muscle of the ileum

NeuroGASTRO Conference, Istanbul, TURKEY, JUN 04-06, 2015International audienc

Dataset on significant role of Candesartan on cognitive functions in rats having memory impairment induced by electromagnetic waves

Rapid growing of mobile phones users has raised about the possible effects of these electromagnetic waves (EMW) on human health. Many studies have examined the role of these EMW on biological systems, but the results are still contradictory and controversial. In addition to EMW, over-activation of angiotensin type 1 receptor (AT1R) has been associated with cognitive decline, incidence and progression of neurodegenerative diseases. Candesartan, an AT1R blocker, is well recognized for treatment of hypertension. However, its role on cognitive functions such as spatial and recognition memory remains elusive. Thus, young rats were divided into 3 groups: control, exposed to radiofrequency electromagnetic waves (EMW), and exposed to EMW during Candesartan treatment (EMW+Cand). Spatial memory performance was assessed using the object recognition test and recognition memory performance using Morris water maze test. Significant differences where found between EMW exposed rats and EMW+Cand exposed rats treated with Candesartan compared to control, EMW group impaired learning, spatial and short term memory along with unaffected sensorimotor function whereas EMW+Cand group improved learning, spatial memory and short term memory deficit induced by EMW in addition to absence of its role on sensorimotor function. Although our data provides evidences of the protective role of Candesartan against EMW-induced cognitive decline, more future studies are still needed to confirm these findings which can provide new fields in treatment of EMW-induced damage by Candesartan. Keywords: Candesartan, Electromagnetic waves, Rat

Impact of prenatal and postnatal exposure to the pesticide chlorpyrifos on the contraction of rat ileal muscle strips: involvement of an inducible nitric oxide synthase-dependent pathway

International audienceBackgroundPrenatal/postnatal exposure to insecticides has been linked to developmental disorders in adulthood. Chlorpyrifos (CPF) is a widely used organophosphorus acetylcholinesterase (AChE)-inhibiting insecticide. The present study established whether prenatal and postnatal exposure to CPF is associated with intestinal motor dysfunction in adult rats. MethodsThree groups of pregnant rats were exposed to either CPF (1 or 5mg/kg/day; the CPF1 and CPF5 groups) or vehicle (the control group) by gavage from gestational day 1 until weaning. At weaning, the pups were separated from their dams and individually gavaged (with the same dose) until postnatal day 60. We then measured in vivo intestinal transit and the in vitro contractile responses of ileal smooth muscle strips to electrical field stimulation. Expression of inducible nitric oxide synthase (iNOS) in the ileum was determined using qRT-PCR and immunoblots. Morphometry and AChE assays were also performed. Key ResultsAt adulthood, the mean body mass was lower in the CPF1 and CPF5 groups than in controls. CPF5 exposure was associated with weaker in vitro contraction of ileal muscle strips, which was reversed by adding the NOS inhibitor (L-NAME). There was no significant intergroup difference in the mean in vivo transit time. Exposure to CPF was associated with greater iNOS expression, lower AChE activity and reduced circular and longitudinal smooth muscle thickness. Conclusions & InferencesPrenatal and postnatal exposure to CPF in the rat is associated with weaker contraction of ileal longitudinal smooth muscle via a nitrergic mechanism with increased iNOS expression

Impacts of perigestational exposure to chlorpyrifos (CPF) and high -fat diet (HFD) on ileum contractility in male rats

International audienc