Browsing by Subject "MDMA"

Now showing 1 - 6 of 6
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    Independent of 5-HT1A receptors, neurons in the paraventricular hypothalamus mediate ACTH responses from MDMA
    (Elsevier, 2013-10-25) Zaretsky, Dmitry V.; Zaretskaia, Maria V.; DiMicco, Joseph A.; Durant, Pamela J.; Ross, Christian T.; Rusyniak, Daniel E.; Emergency Medicine, School of Medicine
    Acute and chronic complications from the substituted amphetamine 3,4-methylenedioxymethamphetamine (MDMA) are linked to activation of the hypothalamic-pituitary-adrenal (HPA) axis. How MDMA activates the HPA axis is not known. HPA responses to stress are known to be mediated through the paraventricular (PVH) hypothalamus and to involve serotonin-1a (5-HT1A) receptors. We sought to determine if the PVH and 5-HT1A receptors were also involved in mediating HPA responses to MDMA. Rats were pretreated with either saline or a 5-HT1A antagonist, WAY-100635 (WAY), followed by a systemic dose of MDMA (7.5mg/kg i.v.). Animals pretreated with WAY had significantly lower plasma ACTH concentrations after MDMA. To determine if neurons in the PVH were involved, and if their involvement was mediated by 5-HT1A receptors, rats implanted with guide cannulas targeting the PVH were microinjected with the GABAA receptor agonist muscimol, aCSF, or WAY followed by MDMA. Compared to aCSF, microinjections of muscimol significantly attenuated the MDMA-induced rise in plasma ACTH (126 vs. 588pg/ml, P=<0.01). WAY had no effect. Our data demonstrates that neurons in the PVH, independent of 5-HT1A receptors, mediate ACTH responses to MDMA.
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    Inhibition of the dorsomedial hypothalamus, but not the medullary raphe pallidus, decreases hyperthermia and mortality from MDMA given in a warm environment.
    (Wiley, 2014-04) Zaretsky, Dmitry V.; Zaretskaia, Maria V.; Durant, Pamela J.; Rusyniak, Daniel E.; Department of Medicine, IU School of Medicine
    The central mechanisms through which MDMA mediates life-threatening hyperthermia when taken in a warm environment are not well described. It is assumed that MDMA alters normal thermoregulatory circuits resulting in increased heat production through interscapular brown adipose tissue (iBAT) and decreased heat dissipation through cutaneous vasoconstriction. We studied the role of the dorsomedial hypothalamus (DMH) and medullary raphe pallidus (mRPa) in mediating iBAT, tail blood flow, and locomotor effects produced by MDMA. Rats were instrumented with guide cannulas targeting either the DMH or the mRPa-brain regions involved in regulating iBAT and cutaneous vascular beds. In all animals, core temperature and locomotion were recorded with surgically implanted telemetric transmitters; and additionally either iBAT temperature (via telemetric transmitter) or tail artery blood flow (via tail artery Doppler cuff) were also recorded. Animals were placed in an environmental chamber at 32°C and microinjected with either control or the GABA agonist muscimol (80pmol) followed by an intravenous injection of saline or MDMA (7.5 mg kg-1). To prevent undue suffering, a core temperature of 41°C was chosen as the surrogate marker of mortality. Inhibition of the DMH, but not the mRPa, prevented mortality and attenuated hyperthermia and locomotion. Inhibition of either the DMH or the mRPa did not affect iBAT temperature increases or tail blood flow decreases. While MDMA increases iBAT thermogenesis and decreases heat dissipation through cutaneous vasoconstriction, thermoregulatory brain regions known to mediate these effects are not involved. Rather, the finding that inhibiting the DMH decreases both locomotion and body temperature suggests that locomotion may be a key central contributor to MDMA-evoked hyperthermia.
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    MDMA Decreases Gluatamic Acid Decarboxylase (GAD) 67-Immunoreactive Neurons in the Hippocampus and Increases Seizure Susceptibility: Role for Glutamate
    (Elsevier, 2016-12) Huff, Courtney L.; Morano, Rachel L.; Herman, James P.; Yamamoto, Bryan K.; Gudelsky, Gary A.; Pharmacology and Toxicology, School of Medicine
    3,4-Methylenedioxy-methamphetamine (MDMA) is a unique psychostimulant that continues to be a popular drug of abuse. It has been well documented that MDMA reduces markers of 5-HT axon terminals in rodents, as well as humans. A loss of parvalbumin-immunoreactive (IR) interneurons in the hippocampus following MDMA treatment has only been documented recently. In the present study, we tested the hypothesis that MDMA reduces glutamic acid decarboxylase (GAD) 67-IR, another biochemical marker of GABA neurons, in the hippocampus and that this reduction in GAD67-IR neurons and an accompanying increase in seizure susceptibility involve glutamate receptor activation. Repeated exposure to MDMA (3×10mg/kg, ip) resulted in a reduction of 37–58% of GAD67-IR cells in the dentate gyrus (DG), CA1, and CA3 regions, as well as an increased susceptibility to kainic acid-induced seizures, both of which persisted for at least 30 days following MDMA treatment. Administration of the NMDA antagonist MK-801 or the glutamate transporter type 1 (GLT-1) inducer ceftriaxone prevented both the MDMA-induced loss of GAD67-IR neurons and the increased vulnerability to kainic acid-induced seizures. The MDMA-induced increase in the extracellular concentration of glutamate in the hippocampus was significantly diminished in rats treated with ceftriaxone, thereby implicating a glutamatergic mechanism in the neuroprotective effects of ceftriaxone. In summary, the present findings support a role for increased extracellular glutamate and NMDA receptor activation in the MDMA-induced loss of hippocampal GAD67-IR neurons and the subsequent increased susceptibility to evoked seizures.
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    MDMA Increases Excitability in the Dentate Gyrus: Role of 5HT2A Receptor Induced PGE2 Signaling
    (Wiley, 2016-03) Collins, Stuart A.; Huff, Courtney; Chiaia, Nicolas; Gudelsky, Gary A.; Yamamoto, Bryan K.; Department of Pharmacology and Toxicology, IU School of Medicine
    MDMA is a widely abused psychostimulant which causes release of serotonin in various forebrain regions. Recently, we reported that MDMA increases extracellular glutamate concentrations in the dentate gyrus, via activation of 5HT2A receptors. We examined the role of prostaglandin signaling in mediating the effects of 5HT2A receptor activation on the increases in extracellular glutamate and the subsequent long-term loss of parvalbumin interneurons in the dentate gyrus caused by MDMA. Administration of MDMA into the dentate gyrus of rats increased PGE2 concentrations which was prevented by coadministration of MDL100907, a 5HT2A receptor antagonist. MDMA-induced increases in extracellular glutamate were inhibited by local administration of SC-51089, an inhibitor of the EP1 prostaglandin receptor. Systemic administration of SC-51089 during injections of MDMA prevented the decreases in parvalbumin interneurons observed 10 days later. The loss of parvalbumin immunoreactivity after MDMA exposure coincided with a decrease in paired-pulse inhibition and afterdischarge threshold in the dentate gyrus. These changes were prevented by inhibition of EP1 and 5HT2A receptors during MDMA. Additional experiments revealed an increased susceptibility to kainic acid-induced seizures in MDMA treated rats which could be prevented with SC51089 treatments during MDMA exposure. Overall, these findings suggest that 5HT2A receptors mediate MDMA-induced PGE2 signaling and subsequent increases in glutamate. This signaling mediates parvalbumin cell losses as well as physiologic changes in the dentate gyrus, suggesting that the lack of the inhibition provided by these neurons increases the excitability within the dentate gyrus of MDMA treated rats.
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    Pharmacokinetic data of synthetic cathinones in female Sprague-Dawley rats
    (Elsevier, 2018-10-25) Grecco, Gregory G.; Kisor, David F.; Sprague, Jon E.; Medicine, School of Medicine
    The synthetic cathinones methylone, butylone, and pentylone differ from each other through the one carbon lengthening of the α-alkyl chain: methylone (-CH3), butylone (-CH2CH3), and pentylone (-CH2CH2CH3) while 3,4-methylenedioxymethamphetamine (MDMA) differs from methylone by a single oxygen atom. Studies with MDMA, suggests that there may be male and female pharmacokinetic and pharmacodynamic differences. In the present study, we present the plasma pharmacokinetic data relative to a 20 mg/kg, subcutaneous doses of methylone, butylone and pentylone in female Sprague-Dawley rats. Briefly, plasma samples were collected via a jugular vein cannula, purified, and analyzed using a HPLC system. While we have previously reported on the consistent relationship between structure and pharmacokinetics of these synthetic cathinones in male, Sprague-Dawley rats (Grecco and Sprague, 2016), this data set suggests that there is no consistent relationship of chemical structure and pharmacokinetics of methylone, butylone and pentylone in female Sprague-Dawley rats. The findings from the present study further emphasize the need for the inclusion of female subjects in the pharmacokinetic studies of synthetic cathinones as it is very possible male-female differences may exist in rodent models.
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    Treadmill running restores MDMA-mediated hyperthermia prevented by inhibition of the dorsomedial hypothalamus
    (Elsevier, 2015-05-22) Zaretsky, Dmitry V.; Zaretskaia, Maria V.; Durant, Pamela J.; Rusyniak, Daniel E.; Department of Emergency Medicine, IU School of Medicine
    The contribution of exercise to hyperthermia mediated by MDMA is not known. We recently showed that inhibiting the dorsomedial hypothalamus (DMH) attenuated spontaneous locomotion and hyperthermia and prevented deaths in rats given MDMA in a warm environment. The goal of this study was to confirm that restoring locomotion through a treadmill would reverse these effects thereby confirming that locomotion mediated by the DMH contributes to MDMA-mediated hyperthermia. Rats were randomized to receive bilateral microinjections, into the region of the DMH, of muscimol (80pmol/100nl) or artificial CSF followed by a systemic dose of either MDMA (7.5mg/kg, i.v.) or saline. Immediately after the systemic injection, rats were placed on a motorized treadmill maintained at 32°C. Rats were exercised at a fixed speed (10m/min) until their core temperature reached 41°C. Our results showed that a fixed exercise load abolished the decreases in temperature and mortality, seen previously with inhibition of the DMH in freely moving rats. Therefore, locomotion mediated by neurons in the DMH is critical to the development of hyperthermia from MDMA.