The psychomotor, reinforcing, and discriminative stimulus effects of synthetic cathinone mexedrone in male mice and rats.

The chronic use of the novel synthetic cathinone mexedrone, like other psychoactive drugs, can be considered addictive, with a high potential for abuse and the ability to cause psychological dependence in certain users. However, little is known about the neurobehavioral effects of mexedrone in association with its potential for abuse. We investigated the abuse potential for mexedrone abuse through multiple behavioral tests. In addition, serotonin transporter (SERT) levels were measured in the synaptosome of the dorsal striatum, and serotonin (5-HT) levels were measured in the dorsal striatum of acute mexedreone (50 mg/kg)-treated mice. To clarify the neuropharmacological mechanisms underlying the locomotor response of mexedrone, the 5-HT2A receptor antagonist M100907 (0.5 or 1.0 mg/kg) was administered prior to the acute injection of mexedrone in the locomotor activity experiment in mice. Mexedrone (10-50 mg/kg) produced a significant place preference in mice and mexedrone (0.1-0.5 mg/kg/infusion) maintained self-administration behavior in rats in a dose-dependent manner. In the drug discrimination experiment, mexedrone (5.6-32 mg/kg) was fully substituted for the discriminative stimulus effects of cocaine in rats. Mexedrone increased locomotor activity, and these effects were reversed by pretreatment with M100907. Acute mexedrone significantly increased c-Fos expression in the dorsal striatum and decreased SERT levels in the synaptosome of the dorsal striatum of mice, resulting in an elevation of 5-HT levels. Taken together, our results provide the possibility that mexedrone has abuse potential, which might be mediated, at least in part, by the activation of the serotonergic system in the dorsal striatum.

What is the analgesic range of acupuncture stimulus for treating acute pain?

Introduction: Since the analgesic effect of acupuncture stimulation is derived from different mechanisms depending on the type of pain, it is important to know which acupuncture points to stimulate. In this study, to confirm the effect of acupuncture stimulation on acute pain from a neurological point of view, somatosensory evoked potential and sensory threshold changes were evaluated to identify the nerve range that is affected by acupuncture stimulation on LI4 (Hapgok acupuncture point, of the radial nerve) during acute pain. Methods: The subjects were 40 healthy men and women aged 19-35 years. The study was designed as a randomly controlled, crossover trial with acupuncture stimulation at LI4 as the intervention. The washout period for acupuncture stimulation was 2 weeks, and the subjects were divided into two groups, i.e., an acupuncture stimulation group and a nonstimulation group, with 10 men and 10 women in each group. Somatosensory evoked potential measurement was carried out for 5 min by alternately applying 2 HZ-pulse electrical stimulation to the thumb and the little finger of the hand acupunctured with a 64-channel electroencephalogram. The verbal rating scale was used before and after each acupuncture stimulation session. Result and discussion: The results of the study confirmed that the somatosensory evoked potential amplitude value of the thumb was significantly decreased and that the intensity of sensory stimulation corresponding to a verbal rating scale score of 6 was significantly increased only in the thumb after acupuncture stimulation. Therefore, the results show that acupuncture treatment for acute pain is more effective when direct acupuncture stimulation is applied to the painful area.

Attenuation of immobilization stress-induced hypertension by temperature-controllable warm needle acupuncture in rats and the peripheral neural mechanisms.

Introduction: We and others have shown that electrical stimulation of the PC-6 acupoint over the wrist relieves hypertension by stimulating afferent sensory nerve fibers and activating the central endogenous opioid system. Warm needle acupuncture has long been utilized to treat various diseases in clinics. Methods: Here, we developed a temperature-controllable warm needle acupuncture instrument (WAI) and investigated the peripheral mechanism underlying the effect of warm needle acupuncture at PC-6 on hypertension in a rat model of immobilization stress-induced hypertension. Results: Stimulation with our newly developed WAI and traditional warm needle acupuncture attenuated hypertension development. Such effects were reproduced by capsaicin (a TRPV1 agonist) injection into PC-6 or WAI stimulation at 48°C. In contrast, PC-6 pretreatment with the TRPV1 antagonist capsazepine blocked the antihypertensive effect of WAI stimulation at PC-6. WAI stimulation at PC-6 increased the number of dorsal root ganglia double-stained with TRPV1 and CGRP. QX-314 and capsaicin perineural injection into the median nerve for chemical ablation of small afferent nerve fibers (C-fibers) prevented the antihypertensive effect of WAI stimulation at PC-6. Additionally, PC-6 pretreatment with RTX ablated the antihypertensive effect of WAI stimulation. Conclusion: These findings suggest that warm needle acupuncture at PC-6 activates C-fiber of median nerve and the peripheral TRPV1 receptors to attenuate the development of immobilization stress-induced hypertension in rats.

Electroacupuncture stimulation of HT7 alleviates sleep disruption following acute caffeine exposure by regulating BDNF-mediated endoplasmic reticulum stress in the rat medial septum.

Acupuncture stimulation can protect the brain against caffeine-induced sleep disruption. This study investigated whether electroacupuncture stimulation acupuncture point HT7 alleviates sleep disruption by regulating mBDNF and ER stress in the medial septum. Acute exposure to caffeine (15 mg/kg, i.p.) increased the wake time and decreased REM sleep, which HT7 stimulation alleviated. HT7 stimulation ameliorated the acute caffeine exposure-induced increase in the expression of BiP, an endoplasmic reticulum stress response protein, in the rat medial septum. Interestingly, HT7 stimulation induced the expression of mBDNF and pTrkB in the medial septum. The next experiment investigated whether TrkB phosphorylated by HT7 stimulation induced BiP expression in the rat medial septum. Before electroacupuncture stimulation at HT7, ANA-12 was administered to caffeine-treated rats. In rats administered ANA-12 in the medial septum, HT7 stimulation did not reduce BiP expression. These findings suggest that HT7 stimulation improves wake time and REM sleep dysfunction by regulating the BDNF-mediated endoplasmic reticulum stress response in the medial septum. These results indicate that the alleviation of endoplasmic reticulum stress in the medial septum by HT7 stimulation and the subsequent amelioration of insomnia may depend on phosphorylated TrkB activation.

Biopotential changes of acupuncture points by acupuncture stimulation.

Background: The energy flow at acupuncture point is important for understanding the mechanism of acupuncture treatment. However, there are few studies on energy at acupuncture point, and related studies have limitation in explaining the energy flow in all meridians. Thus, we aimed to understand the properties of electrical energy at acupuncture point in twelve meridians by measuring the biopotential at acupuncture and non-acupuncture points. Methods: For each meridian, twenty subjects were participated, and biopotential was measured at five transport points and their adjacent non-acupuncture points. In each subject, both 'non-stimulation' and 'stimulation' experiments were conducted in random order. The data were analyzed in two parts: biopotential variability and biopotential difference between acupuncture and non-acupuncture points. Results: The biopotential variability at acupuncture point was increased by acupuncture stimulation, and it was related to the activation of Qi flow by acupuncture stimulation. The biopotential difference between acupuncture and non-acupuncture points was formed in the direction related to the Qi flow theory, and this biopotential difference tended to decrease by acupuncture stimulation. Conclusion: The study on biopotential can provide a foundation for research on energy flow mechanism of acupuncture stimulation, and it is expected to overcome limitation of qualitative explanation in traditional medicine.

Interaction of JNK and mGluR5 in the regulation of psychomotor behaviours after repeated cocaine administration.

Activation of protein kinases after cocaine administration controls psychomotor behaviours by interacting with metabotropic receptors in the brain. This study identified how c-Jun N-terminal kinase (JNK) interacts with metabotropic glutamate receptor 5 (mGluR5) in vitro and in the caudate and putamen (CPu). The potential role of this interaction in the regulation of psychomotor behaviour was also evaluated after administration of cocaine. Active JNK phosphorylates a threonine residue at position 1055 in the carboxyl terminus (CT) of mGluR5 in vitro. The binding of active JNK to the D-motif within CT2 is necessary for that phosphorylation. Interaction of phosphorylated JNK and mGluR5 occurs in the CPu. Unilateral interference of the interaction decreases the repeated cocaine-induced increases in locomotor activity and conditioned place preference. These findings suggest that activation of JNK has the capability to interact with mGluR5 in the CPu. Phosphorylation of mGluR5 following the JNK-mGluR5 interaction may be responsible for the potentiation of behavioural sensitisation and cocaine-wanting behaviour in response to cocaine administration.

Inhibition of Spinal TRPV1 Reduces NMDA Receptor 2B Phosphorylation and Produces Anti-Nociceptive Effects in Mice with Inflammatory Pain.

Transient receptor potential vanilloid 1 (TRPV1) has been implicated in peripheral inflammation and is a mediator of the inflammatory response to various noxious stimuli. However, the interaction between TRPV1 and N-methyl-D-aspartate (NMDA) receptors in the regulation of inflammatory pain remains poorly understood. This study aimed to investigate the analgesic effects of intrathecal administration of capsazepine, a TRPV1 antagonist, on carrageenan-induced inflammatory pain in mice and to identify its interactions with NMDA receptors. Inflammatory pain was induced by intraplantar injection of 2% carrageenan in male ICR mice. To investigate the analgesic effects of capsazepine, pain-related behaviors were evaluated using von Frey filaments and a thermal stimulator placed on the hind paw. TRPV1 expression and NMDA receptor phosphorylation in the spinal cord and glutamate concentration in the spinal cord and serum were measured. Intrathecal treatment with capsazepine significantly attenuated carrageenan-induced mechanical allodynia and thermal hyperalgesia. Moreover, carrageenan-enhanced glutamate and phosphorylation of NMDA receptor subunit 2B in the spinal cord were suppressed by capsazepine administration. These results indicate that TRPV1 and NMDA receptors in the spinal cord are associated with inflammatory pain transmission, and inhibition of TRPV1 may reduce inflammatory pain via NMDA receptors.

Acupuncture stimulation at HT7 as a non-pharmacological therapy for sleep disorder caused by caffeine administration in rats.

OBJECTIVES: Insomnia is one of the most common sleep disorders and is difficult to completely treat because of the undesirable side effects of hypnotics. The present study was designed to investigate the hypnotic effect of acupuncture stimulation at HT7 on caffeine-induced sleep disorders and locomotor activity in rats. We also evaluated neuronal activity changes in the arousal region of the basal forebrain. METHODS: Rats received intraperitoneal injections of caffeine, and then electroencephalogram power spectrum analysis and locomotor activity measurements were performed. Stimulation at HT7 was performed using a mechanical acupuncture instrument (MAI) before caffeine injection, and its effects on caffeine-induced changes in sleep architecture, locomotor activity and c-Fos expression were examined. RESULTS: Caffeine injection (7.5 mg/kg) produced a significant decrease in slow-wave sleep and an increase in wake time compared with saline injection. Caffeine injection also increased locomotor activity and c-Fos expression in the medial septum-vertical limb of the diagonal band of Broca (MS-VDB), one of the arousal regions of the basal forebrain. Stimulation at HT7 with the MAI alleviated the caffeine-induced sleep disturbance and the increase in locomotor activity. In addition, MAI treatment at HT7, compared with treatment at a location not corresponding to any traditional acupuncture point, reduced the caffeine-induced increase in c-Fos expression. CONCLUSION: These results indicate that the hypnotic effect of HT7 acupuncture stimulation on caffeine-induced insomnia was associated with suppression of neuronal activity in the basal forebrain.

Acupuncture Alleviates Anxiety and 22-kHz Ultrasonic Vocalizations in Rats Subjected to Repeated Alcohol Administration by Modulating the Brain-Derived Neurotrophic Factor/Corticotropin-Releasing Hormone Signaling Pathway.

The Shenmen point (acupuncture point heart 7: HT7), located in the heart meridian, is frequently used to treat mental disorders, including drug addiction, anxiety, and depression. This study aimed to determine how HT7 regulates anxiety and negative emotions caused by repeated alcohol administration, focusing on the amygdala and paraventricular nucleus (PVN). Repeated administration of alcohol (ETOH; 2 g/kg, i.p. injection, 16% v/v) for 14 days increased the corticosterone (CORT) levels, and HT7 stimulation reduced the plasma CORT levels. HT7 stimulation mitigated anxiety-like behaviors and reduced 22-kHz ultrasonic vocalizations in rats receiving repeated ETOH injections. HT7 stimulation increased the amygdala expression of mature brain-derived neurotropic factor (mBDNF) and phosphorylated tropomyosin receptor kinase B (pTrkB) and decreased the PVN corticotropin-releasing hormone (CRH) expression. Amygdala microinjections of the TrkB antagonist ANA-12 (0.1 pmol/1 µL) reversed the increase in PVN CRH levels. The reduced PVN CRH levels were regulated by CRH-expressing neurons in the amygdala, and the increased amygdala CRH levels were affected by the HT7-stimulation induced increases in mBDNF. HT7 stimulation alleviates increased stress hormone levels and mitigates anxiety and negative emotions caused by repeated ETOH administration. These results provide scientific support for the clinical use of acupuncture to treat various alcoholism-induced diseases.

The effect of acupuncture stimulation on alleviating emotional changes due to acute alcohol administration and the possibility of sigma1 receptor involvement.

BACKGROUND: Most ETOH addiction preclinical studies have focused on the rewards of chronic ETOH self-administration or the ETOH reinstatement model. Acute ETOH administration studies are scarce despite the potential of ETOH to cause sedation, intoxication and reduced acute functional tolerance. Here, we established a rat model of acute ETOH administration induced by an intraperitoneal injection of 1 g/kg ethanol and assessed the similarities in physiological and behavioral effects between acupuncture and Sigma1 R antagonists. METHODS: Male Wistar rats (300-330 g) received pretreatment with (1) saline injection, (2) saline + mechanical stimulation using a mechanical acupuncture instrument (MAI) for acupuncture at the Shenmen (HT7), (3) ETOH (1 g/kg) injection, (4) ETOH + HT7, or (5) the selective σ1 R antagonist BD 1047 (3, 10, or 30 mg/kg, intraperitoneal (IP) injection). ETOH (1 g/kg) or saline was IP injected after 10 min. Then, ETOH-induced immobility was evaluated in an open field arena, ultrasonic vocalizations (USVs) indicating ethanol-induced emotional changes were recorded in a recording chamber, and the rats were sacrificed for the analysis of protein levels of σ1 R in several regions of the brain. RESULTS: Acute ethanol exposure increased the immobile time, 22-kHz USVs, and protein levels of σ1 R in the ventral tegmental area (VTA). However, pretreatment with acupuncture at HT7 induced recovery of immobile time, reduced 22-kHz USVs, and regulated the protein levels of σ1 R in the VTA. These effects have similarities with IP injection of BD 1047 (10 mg/kg). CONCLUSION: This study showed that acupuncture at HT7 regulates immobility and 22-kHz USVs via Sigma1 R in the VTA upon acute ETOH exposure.

Exposure to Commercial Cigarette Smoke Produces Psychomotor Sensitization Via Hyperstimulation of Glutamate Response in the Dorsal Striatum.

Cigarette smoke is a highly complex mixture of nicotine and non-nicotine constituents. Exposure to cigarette smoke enhances tobacco dependence by potentiating glutamatergic neurotransmission via stimulation of nicotinic acetylcholine receptors (nAChRs). We investigated the effects of nicotine and non-nicotine alkaloids in the cigarette smoke condensates extracted from two commercial cigarette brands in South Korea (KCSC A and KCSC B) on psychomotor behaviors and glutamate levels in the dorsal striatum. Repeated and challenge administration of KCSCs (nicotine content: 0.4 mg/kg, subcutaneous) increased psychomotor behaviors (ambulatory, rearing, and rotational activities) and time spent in psychoactive behavioral states compared to exposure to nicotine (0.4 mg/kg) alone. The increase in psychomotor behaviors lasted longer when exposed to repeated and challenge administration of KCSCs compared to nicotine alone. In parallel with sustained increase in psychomotor behaviors, repeated administration of KCSCs also caused long-lasting glutamate release in the dorsal striatum compared to nicotine alone. KCSC-induced changes in psychomotor behaviors and glutamate levels in the dorsal striatum were found to be strongly correlated. These findings suggest that non-nicotine alkaloids in commercial cigarette smoke synergistically act with nicotine on nAChRs, thereby upregulating glutamatergic response in the dorsal striatum, which contributes to the hypersensitization of psychomotor behaviors.

Treatment of electrical wrist stimulation reduces chemotherapy-induced neuropathy and ultrasound vocalization via modulation of spinal NR2B phosphorylation.

Docetaxel, a chemotherapeutic agent used to treat breast cancer, produces a robust painful neuropathy that is aggravated by mechanical and thermal stimuli. This study was undertaken to investigate the analgesic effects of electrical stimulation on docetaxel-induced neuropathic pain in mice and to identify associated changes in ultrasound vocalizations. Peripheral neuropathy was induced with intraperitoneally injected docetaxel (5 mg/kg) on 3 times every 2 days in male ICR mice. Electrical wrist stimulation was administered and pain behavior signs were evaluated by von Frey filaments and thermal stimulation on the hind paw. Ultrasound vocalizations were measured using ultrasound microphones, after electrical stimulation. After mice developed docetaxel-induced neuropathic pain behavior, an electrical stimulation temporarily attenuated mechanical allodynia and thermal hyperalgesia. In formalin and NMDA test, pain-induced mice showed increases in 10-30 kHz ultrasound vocalizations, but not in 30-50 and 50-80 kHz vocalizations. Treatment with docetaxel selectively increased 10-30 kHz ultrasound vocalizations, whereas electrical stimulation caused a meaningful decrease. Moreover, electrical stimulation suppressed the docetaxel-enhanced phosphorylation of the NMDA receptor NR2B subunit in the spinal dorsal horn. These results of the analgesic effect of electrical stimulation in chemotherapy-induced neuropathy could potentially provide a new method to treat and manage peripheral neuropathy in patients with cancer.

Biological safety of Electroacupuncture with STS316 needles.

BACKGROUND: Electroacupuncture (EA) is often used in clinical settings due to its analgesic effect, but its safety has not been verified due to the lack of clear criteria. This study examined the critical range of the corrosion of stainless steel types STS304 and STS316, which have been used clinically, and the relationship between needle corrosion and cell necrosis. METHOD: The critical point of corrosion for STS304 and STS316 was identified by varying the time, frequency, and stimulation intensity. In a tissue necrosis experiment, EA stimulation was applied to rats using STS316 needles with different thicknesses at maximum intensity for 60 min, and the presence of corrosion and tissue necrosis was determined. A cytotoxicity experiment was also conducted and assessed the needles and tissue necrosis. RESULTS: The results showed that STS316 was more stable than STS304 and that only coated needles corroded. Furthermore, tissue necrosis was observed regardless of corrosion, and slight cell necrosis was associated with needles with corrosion. CONCLUSIONS: This study demonstrated that non-coated STS316 was the most stable for EA stimulation and that corrosion byproducts and cell necrosis were not directly related.

A mechanical acupuncture instrument mitigates the endoplasmic reticulum stress and oxidative stress of ovariectomized rats.

BACKGROUND: Acupuncture has become a common complementary and alternative treatment approach for anxiety and depression. However, there is little research on the detailed mechanism of acupuncture therapy relieving depression. Previously, 17ß-estradiol (E2) was shown to prevent oxidative stress and endoplasmic reticulum (ER) stress in ovariectomized (OVX) rats. This study investigated whether stimulation of Sanyinjiao (SP6) using a mechanical acupuncture instrument can alleviate depression-like behavior caused by estrogen deficiency in OVX rats. Furthermore, we found that acupuncture reduced ER stress and oxidative stress-related proteins expression. METHODS: The OVX operation was performed on female SD rats that were separated into four groups: The E2 (2.5 µg/kg, i.p.) injection group (OVX + E2), the OVX group (OVX), and the OVX with acupuncture stimulation group (OVX + SP6). Non-acupoint stimulation group (OVX + NonAcu). The acupuncture point stimulation began three weeks after surgery. The depressive behavior was analyzed by the forced swim test and open field test. The 8-OHDG, BiP, Sigma receptor 1, pJNK, PDI, Ero1-Iα and Calnexin protein levels were evaluated by immunoreactivity in the amygdala. RESULTS: Acupuncture stimulation reduced depressive behavior and altered depression-related proteins. Stimulation of SP6 decreased the immobility time of the FST and altered the ER stress and oxidative stress marker proteins, such as 8-OHDG, BiP, pJNK, PDI, Ero1-Ia and Calnexin. CONCLUSION: Our results indicated that acupuncture at SP6 showed a significant antidepressant-like effect on an OVX-induced depression rat model by mitigation of ER stress and oxidative stress in amygdala.

Activation of Protein Kinase G After Repeated Cocaine Administration Is Necessary for the Phosphorylation of α-Amino-3-Hydroxy-5-Methyl-4-Isoxazolepropionic Acid Receptor GluA1 at Serine 831 in the Rat Nucleus Accumbens.

Phosphorylation of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors in the striatum plays a crucial role in regulating the receptor-coupled signaling cascades leading to behavioral changes associated with psychostimulant exposure. The present study determined if activation of protein kinase G (PKG) contributes to the phosphorylation of AMPA receptor GluA1 subunit at the position of serine 831 (GluA1-S831) in the rat nucleus accumbens (NAc) after repeated cocaine administration. The results demonstrated that repeated intraperitoneal (i.p.) injections of cocaine (20 mg/kg) once a day for seven consecutive days significantly increased the level of phosphorylated (p)GluA1-S831. This increase was decreased by the intra-NAc infusion of either the cyclic guanosine monophosphate (cGMP) analog, Rp-8-Br-PET-cGMPS (5 nmol/1 µL), or the PKG inhibitor, KT5823 (2 nmol/1 µL). Repeated cocaine administration increased PKG binding activity to GluA1. This increase in GluA1-S831 phosphorylation after repeated cocaine administration was decreased by the intra-NAc infusion of the synthetic peptide (Tat-tagged interfering peptide (Tat-GluA1-i)), that interferes with the binding of PKG to GluA1. Intra-NAc infusion of the interfering peptide also reduced the repeated cocaine-induced increase in locomotor activity. These findings suggest that activated PKG, after repeated exposure to cocaine, binds to AMPA receptor GluA1 and is required for the phosphorylation of S831, contributing to behavioral changes.

Repeated Administration of Cigarette Smoke Condensate Increases Glutamate Levels and Behavioral Sensitization.

Nicotine, a nicotinic acetylcholine receptor agonist, produces the reinforcing effects of tobacco dependence by potentiating dopaminergic and glutamatergic neurotransmission. Non-nicotine alkaloids in tobacco also contribute to dependence by activating the cholinergic system. However, glutamatergic neurotransmission in the dorsal striatum associated with behavioral changes in response to cigarette smoking has not been investigated. In this study, the authors investigated alterations in glutamate levels in the rat dorsal striatum related to behavioral alterations after repeated administration of cigarette smoke condensate (CSC) using the real-time glutamate biosensing and an open-field behavioral assessment. Repeated administration of CSC including 0.4 mg nicotine (1.0 mL/kg/day, subcutaneous) for 14 days significantly increased extracellular glutamate concentrations more than repeated nicotine administration. In parallel with the hyperactivation of glutamate levels, repeated administration of CSC-evoked prolonged hypersensitization of psychomotor activity, including locomotor and rearing activities. These findings suggest that the CSC-induced psychomotor activities are closely associated with the elevation of glutamate concentrations in the rat dorsal striatum.

An estradiol-independent BDNF-NPY cascade is involved in the antidepressant effect of mechanical acupuncture instruments in ovariectomized rats.

Menopause-related depression devastates women's quality of life after middle age. Previous research has shown that estrogen hormone therapy has serious adverse effects; thus, complementary and integrative therapies have been considered clinically. The present study investigates whether stimulation of an acupoint using a mechanical acupuncture instrument (MAI) can mitigate depression-like behavior caused by estrogen deficiency in ovariectomized (OVX) rats. The animals were divided into Sham OVX, OVX, OVX + Sameumgyo (SP6) and OVX + NonAcu (non-acupuncture point) groups. MAI stimulation significantly increased the total distance traveled in the open-field test and the number of open-arm entries in the elevated plus maze and decreased the duration of immobility in the forced swim test. In addition to this decrease in depression-like behavior, brain-derived neurotrophic factor (BDNF) and neuropeptide Y (NPY) release increased in the hippocampus in response to MAI treatment, but estradiol levels did not recover. Furthermore, microinjection of the BDNF receptor antagonist ANA-12 (0.1 pmol/1 µl) into the hippocampus before MAI stimulation significantly suppressed the recovery of NPY levels. Taken together, these findings indicate that MAI stimulation at SP6 facilitates an estradiol-independent BDNF-NPY cascade, which may contribute to its antidepressant effects in OVX rats, an animal model of menopausal disorders.

Behavioral changes after nicotine challenge are associated with α7 nicotinic acetylcholine receptor-stimulated glutamate release in the rat dorsal striatum.

Neurochemical alterations associated with behavioral responses induced by re-exposure to nicotine have not been sufficiently characterized in the dorsal striatum. Herein, we report on changes in glutamate concentrations in the rat dorsal striatum associated with behavioral alterations after nicotine challenge. Nicotine challenge (0.4 mg/kg/day, subcutaneous) significantly increased extracellular glutamate concentrations up to the level observed with repeated nicotine administration. This increase occurred in parallel with an increase in behavioral changes in locomotor and rearing activities. In contrast, acute nicotine administration and nicotine withdrawal on days 1 and 6 did not alter glutamate levels or behavioral changes. Blockade of α7 nicotinic acetylcholine receptors (nAChRs) significantly decreased the nicotine challenge-induced increases in extracellular glutamate concentrations and locomotor and rearing activities. These findings suggest that behavioral changes in locomotor and rearing activities after re-exposure to nicotine are closely associated with hyperactivation of the glutamate response by stimulating α7 nAChRs in the rat dorsal striatum.

Saururus chinensis Baill inhibits proliferation and invasion of human renal cell carcinoma cells through inhibition of inhibitor of apoptosis protein.

OBJECTIVE: To investigate the inhibitory effect of Saururus chinensis Baill on cell viability, apoptosis, invasion capacity and the mechanism involved in human renal cell carcinoma (RCC) cells. METHODS: After treating A498 and ACHN cells with Saururus chinensis Baill extract (0, 25, 50 µg/mL), inhibitory effect of Saururus chinensis Baill were evaluated using tetrazolium salt-based colorimetric assay, flfl ow cytometry analysis, and in vitro Matrigel invasion assay, respectively. To determine the molecular mechanisms of Saururus chinensis Baill, expression of inhibitor of apoptosis proteins (IAP) were assessed using reverse transcription polymerase chain reaction (RT-PCR) and Western blot. The levels of cytochrome C and caspase-3 proteins were assessed by Western blot. RESULTS: Saururus chinensis Baill suppressed cell viability and invasion capacity and induced apoptosis of A498 and ACHN cells in a time- and concentration-dependent manner. RT-PCR and Western blot analysis showed that Saururus chinensis Baill inhibited the expressions of cellular inhibitor of apoptosis (cIAP)-1, cIAP-2, X-linked inhibitor of apoptosis protein, and survivin. This was accompanied by the release of cytochrome C and activation of caspase-3 proteins. CONCLUSIONS: Saururus chinensis Baill can inhibit human RCC cell growth by inducing cancer cell apoptosis, and these effects are mediated by the down-regulation of IAP proteins and subsequent release of cytochrome C and activation of caspase-3.

Activation of Protein Kinases and Phosphatases Coupled to Glutamate Receptors Regulates the Phosphorylation State of DARPP32 at Threonine 75 After Repeated Exposure to Cocaine in the Rat Dorsal Striatum in a Ca2+-Dependent Manner.

BACKGROUND: Phosphorylation state of dopamine- and cAMP-regulated phosphoprotein, molecular weight 32 kDa (DARPP32) is crucial to understand drug-mediated synaptic plasticity. In this study, mechanisms underlying repeated cocaine-stimulated phosphorylation of DARPP32 at threonine 75 (pDARPP32-Thr75) were determined by investigating the hypothesis that activation of protein kinases and phosphatases coupled to glutamate signaling is necessary for the regulation of pDARPP32-Thr75 after repeated cocaine administration. METHODS: Intracaudate drug infusions into the rat dorsal striatum followed by Western immunoblot analysis were mainly performed to test this hypothesis. RESULTS: The results demonstrated that 7 repeated daily intraperitoneal injections of cocaine (20mg/kg) upregulated the expression of pDARPP32-Thr75. Increases in the cytosolic Ca(2+) concentrations followed by Ca(2+)-dependent protein kinase activation through stimulation of Ca(2+) channels in striatal neurons were necessary for the phosphorylation. Activation of protein phosphatases further regulated the phosphorylation state by deactivating pDARPP32-Thr75 and upstream protein kinases. CONCLUSION: These findings suggest that activation of protein kinases and phosphatases coupled to glutamate receptors controls the phosphorylation state of DARPP32-Thr75 after repeated exposure to cocaine in the dorsal striatum in a Ca(2+)-dependent manner.