Reduced GABA-B/GIRK-mediated regulation of the VTA following a single exposure to cocaine

In this paper, Arora and colleagues expand on their previous work on GIRK channels in the ventral tegmental area (VTA) presenting evidence that a single exposure to cocaine reduces inhibitory GABAergic transmission to dopamine (DA) neurons in the ventral tegmental area. Mice receiving i.p. injections of cocaine saw a short lived (1-5 days) decrease in GABAb mediated G-protein coupled inwardly-rectifying potassium (GIRK) currents in DA neurons in the VTA. This decrease parallels an NMDA-mediated increase in the frequency of glutamatergic neurotransmission. Chronic cocaine injections had no additional effects beyond those seen with single injections. Though they found no change in mRNA levels for GABAb receptors, GIRK channels, or RGS-2 (a G-protein regulator), immunoelectron microscopy indicated a decrease in levels of GIRK channels in the plasma membrane of the dendrites of VTA DA neurons. The cocaine-mediated decrease in GIRK currents was abolished in the presence of D2/3R antagonist sulpiride, but not in the presence of D1/5 antagonist SCH23390, indicating a link between D2/3 receptor activation and GIRK activity. Interestingly, the addition of quinpirole, a D2/3 agonist, elicited similar GIRK currents, though they were smaller than those mediated by GABAb receptors. Similarly, acute injections of cocaine significantly diminished quinpirole-evoked currents

Cocaine self-administration in the mouse: A low-cost, chronic catheter preparation

Intravenous drug self-administration is the most valid animal model of human addiction because it allows volitional titration of the drug in the blood based on an individual’s motivational state together with the pharmacokinetic properties of the drug. Here we describe a reliable low-cost mouse self-administration catheter assembly and protocol that that can be used to assess a variety of drugs of abuse with a variety of protocols. We describe a method for intravenous catheter fabrication that allows for efficient and long-lasting intravenous drug delivery. The intravenous catheters remained intact and patent for several weeks allowing us to establish stable maintenance of cocaine acquisition. This was followed by a dose response study in the same mice. For collaborators interested in premade catheters for research please make a request at www.neuro-cloud.net/nature-precedings/pomerenze

Mutation in Tg737 Gene Shortens Neuronal Cilia in Mice

Honors thesis written by a student in the UNT Honors College discussing mutations in the Tg737 gene in mice and how this affects neuronal cilia in mice

Reinforcing Effect of Optogenetic Stimulation of Dorsal Subiculum

The subiculum is a subregion of the hippocampus that sends projections from the hippocampus to several cortical and limbic structures involved in mediating motivated behaviors such as the medial prefrontal cortex (mPFC), nucleus accumbens (Nacc), amygdala, and hypothalamus. Electrophysiological and pharmacological studies have demonstrated that the subiculum itself can modulate certain motivated behaviors. Prior work has often focused on the ventral portion of the subiculum (vSUB), as electrically stimulating the vSUB can induce reinstatement of cocaine seeking behavior. However, no studies to date have shown whether stimulation of the dorsal subiculum (dSUB) can affect operant responding or motivated behavior. Here we demonstrate that mice placed in custom built operant nose poke chambers will nose poke for optogenetic stimulation of the dSUB. This reinforcing effect was significantly greater than baseline nose poking rates or poking for a light cue and was dependent on the frequency of stimulation, with increased frequency correlating with increased self-stimulation rates. Stimulating subicular projections to the Nacc also significantly increased self-stimulation rates, indicating a role for dSUB to Nacc projections in mediating the reinforcing effects of self-stimulation. Acute and chronic administration of cocaine had no effect on laser self-stimulation rates, however, administration of dopamine D1 receptor antagonist SCH-23390 or muscarinic acetylcholine receptor (mAChR) antagonist scopolamine significantly reduced laser self-stimulation, suggesting the involvement of dopaminergic and cholinergic systems in mediating laser self-stimulation\u27s reinforcing effects. Together, this data supports a novel role for dSUB projections to the Nacc in mediating control of operant and motivated behaviors

Cocaine self-administration in mice with forebrain knock-down of trpc5 ion channels

Canonical transient receptor potential (TRPC) channels are a family of non-selective cation channels that play a crucial role in modulating neuronal excitability due to their involvement in intracellular Ca2+ regulation and dendritic growth. TRPC5 channels a) are one of the two most prevalent TRPC channels in the adult rodent brain; b) are densely expressed in deep layer pyramidal neurons of the prefrontal cortex (PFC); and c) modulate neuronal persistent activity necessary for working memory and attention. In order to evaluate the causal role of TRPC5 in motivation/reward-related behaviors, conditional forebrain TRPC5 knock-down (trpc5-KD) mice were generated and trained to nose-poke for intravenous cocaine. Here we present a data set containing the first 6 days of saline or cocaine self-administration in wild type (WT) and trpc5-KD mice. In addition, we also present a data set showing the dose-response to cocaine after both groups had achieved similar levels of cocaine self-administration. Compared to WT mice, trpc5-KD mice exhibited an apparent increase in self-administration on the first day of cocaine testing without prior operant training. There were no apparent differences between WT and trpc5-KD mice for saline responding on the first day of training. Both groups showed similar dose-response sensitivity to cocaine after several days of achieving similar levels of cocaine intake.</ns4:p

Cellular Phone-Based Image Acquisition and Quantitative Ratiometric Method for Detecting Cocaine and Benzoylecgonine for Biological and Forensic Applications

Here we describe the first report of using low-cost cellular or web-based digital cameras to image and quantify standardized rapid immunoassay strips as a new point-of-care diagnostic and forensics tool with health applications. Quantitative ratiometric pixel density analysis (QRPDA) is an automated method requiring end-users to utilize inexpensive (~ $1 USD/each) immunotest strips, a commonly available web or mobile phone camera or scanner, and internet or cellular service. A model is described whereby a central computer server and freely available IMAGEJ image analysis software records and analyzes the incoming image data with time-stamp and geo-tag information and performs the QRPDA using custom JAVA based macros ( http://www.neurocloud.org ). To demonstrate QRPDA we developed a standardized method using rapid immunotest strips directed against cocaine and its major metabolite, benzoylecgonine. Images from standardized samples were acquired using several devices, including a mobile phone camera, web cam, and scanner. We performed image analysis of three brands of commercially available dye-conjugated anti-cocaine/benzoylecgonine (COC/BE) antibody test strips in response to three different series of cocaine concentrations ranging from 0.1 to 300 ng/ml and BE concentrations ranging from 0.003 to 0.1 ng/ml. This data was then used to create standard curves to allow quantification of COC/BE in biological samples. Across all devices, QRPDA quantification of COC and BE proved to be a sensitive, economical, and faster alternative to more costly methods, such as gas chromatography-mass spectrometry, tandem mass spectrometry, or high pressure liquid chromatography. The limit of detection was determined to be between 0.1 and 5 ng/ml. To simulate conditions in the field, QRPDA was found to be robust under a variety of image acquisition and testing conditions that varied temperature, lighting, resolution, magnification and concentrations of biological fluid in a sample. To determine the effectiveness of the QRPDA method for quantifying cocaine in biological samples, mice were injected with a sub-locomotor activating dose of cocaine (5 mg/kg; i.p.) and were found to have detectable levels of COC/BE in their urine (160.6 ng/ml) and blood plasma (8.1 ng/ml) after 15–30 minutes. By comparison rats self-administering cocaine in a 4 hour session obtained a final BE blood plasma level of 910 ng/ml with an average of 62.5 infusions. It is concluded that automated QRPDA is a low-cost, rapid and highly sensitive method for the detection of COC/BE with health, forensics, and bioinformatics application and the potential to be used with other rapid immunotest strips directed at several other targets. Thus, this report serves as a general reference and method describing the use of image analysis of lateral flow rapid test strips