3,4-Methylenedioxy-N-methamphetamine (ecstasy) promotes the survival of fetal dopamine neurons in culture

Abstract

Summary The current study examined whether modest concentrations of MDMA could increase the survival and/or neurite outgrowth of fetal midbrain dopamine (DA) neurons in vitro since increased DA neurite outgrowth has been previously observed in vivo from prenatal exposure. MDMA concentrations in fetal brain were quantified to determine relevant in vivo concentrations to employ in vitro. A dose-response study in vitro demonstrated that MDMA, at concentrations observed in vivo, resulted in increased, DA-specific, neuron survival. Higher doses resulted in nonspecific neurotoxicity. MDMA application immediately after culture establishment resulted in greater survival than delayed application, however both were superior to control. MDMA significantly increased the expression of the slc6a3 gene (dopamine transporter; DAT) in culture. Co-application of the DAT reuptake inhibitor methylphenidate (MPH) with MDMA attenuated this effect. Progressive reductions in MPH concentrations restored the MDMA-induced survival effect. This suggests that MDMA’s action at DAT mediates the survival effect. Neurite density per neuron was unaffected by MDMA in vitro suggesting that MDMA promotes DA neuron survival but not neurite outgrowth in culture. Finally, animals prenatally exposed to MDMA and examined on postnatal day 35 showed an increase in tyrosine hydroxylase-positive (TH+) neurons in the substantia nigra but not in the ventral tegmental area. These data suggest that during development, MDMA can increase the survival of DA neurons through its action at its transporter. Understanding how MDMA increases DA neuron survival may provide insight into normal DA neuron loss during development.

Prenatal exposure to MDMA alters noradrenergic neurodevelopment in the rat

“…Noradrenergic fiber density was increased in the CA1 region of the HIPP, consistent with the former explanation, however fiber density was comparable to controls in the CA2 and CA3 region, suggesting that the relative innervation of these regions is comparable in both groups, but NET is upregulated in MDMA-treated subjects. We have previously reported findings consistent with the latter hypothesis in the DA system [27]. In this study, we demonstrated that MDMA increases Slc6a3 (DAT) gene expression in primary mesencephalic DA neurons in vitro , and that this was not a result of an increase in neurite density.…”

Effect of levodopa priming on dopamine neuron transplant efficacy and induction of abnormal involuntary movements in parkinsonian rats

“…Ventral mesencephalon (VM) from Fisher 344 rats of embryonic day 14 (E14; crown‐rump length = 10.0–11.5 mm) containing developing A8, A9, and A10 dopamine cell groups was dissected from the ventral floor of the midbrain flexure extending posteriorly to the isthmus and laterally to the sulcus limitans (Lipton et al,2008). After collection, VM tissue was pooled in 4°C calcium‐magnesium‐free buffer, transferred to calcium‐magnesium‐free buffer containing 0.1% trypsin, warmed to 37°C for 10 minutes, rinsed in calcium‐magnesium‐free buffer again, and triturated in 0.004% DNase with Pasteur pipettes of 1.0‐mm and 0.5‐mm tip diameter.…”

Regulation of the dopamine transporter

“…Paradoxically, localized direct administration of MDMA in rats by in vivo reverse microdialysis—at concentrations equivalent to those attained after high‐dose systemic administration—does not result in the typical indicators of serotonergic neurotoxicity, despite eliciting dramatically greater increases in extracellular monoamine levels 131 . Surprisingly, MDMA was demonstrated to exert neuroprotective effects in cultured rat fetal neurons, indicating that direct exposure to the chemical itself is not necessarily cytotoxic 132 . In addition, whereas systemically administered MDA and MDMA acutely increase the concentration of radical reactive oxygen species (ROS) and produce oxidative stress in the brain, direct intracerebroventricular administration is devoid of such effects 131,133 …”

“… Metabolic reaction pathway of MDA‐like compounds leading to the formation of neurotoxic prooxidant thioether species and the relative toxicity of metabolites. The parent compounds MDA and MDMA are not directly cytotoxic 131,132 . However, demethylenation of the 3,4‐methylenedioxy moiety by the hepatic CYP2D6 enzyme 135 results in the formation of 3,4‐dihydroxyamphetamines, which are readily oxidized to quinones 134 .…”