The use of volatile organic solvents as drugs of abuse is an important health problem. These agents, often termed abused inhalants, are voluntarily inhaled or """"""""huffed"""""""" for their intoxicating effects. The use of abused inhalants is especially prevalent among children and adolescents since these compounds are legal and are found in a wide variety of household and commercial products including glues, adhesives and paint thinners. Abused inhalants are associated with a variety of adverse effects ranging from reduced academic performance, brain abnormalities and a sudden-death syndrome resulting from solvent-induced cardiac arrhythmia. Although abused inhalants produce ethanol-like signs of intoxication, their sites and mechanisms of action that underlie these effects are largely unknown. Research carried out during the previous funding period of this project used recombinant expression techniques and electrophysiology to study the effects of abused inhalants on ion channels widely expressed by brain neurons. Results from these studies revealed a surprising degree of selectivity for the effects of abused inhalants on both voltage-gated and ligand-gated ion channels that regulate neuronal excitability. In particular, the NR1/2B NMDA receptors and the 1422 nicotinic acetylcholine receptor were among the most sensitive channels identified. In this application, we focus on the role that these channels play in mediating the effects of toluene, the prototype abused inhalant, on the activity of principal neurons within three brain regions known to be important in mediating the effects of drugs of abuse. Whole-cell patch-clamp electrophysiology will be used to study the effects of toluene on dopamine neurons of the ventral tegmental area (VTA), medium spiny neurons of the nucleus accumbens (NAcc) and deep-layer pyramidal neurons of the prefrontal cortex (PFC).
Aim 1 will determine the toluene sensitivity of NMDA EPSCs within the addiction neurocircuitry with a special focus on NR1/2B receptors.
Aim 2 will determine the effect of acute toluene on VTA DA neuron excitability with a special focus on 1422 nAchRs.
Aim 3 will use a novel triple-slice co-culture system to determine the effects of toluene on NR1/2B and 1422 nAchRs that mediate complex firing patterns produced by PFC neurons. Finally, Aim 4 will test the hypothesis that exposure to toluene in vivo induces changes in indicators of plasticity in glutamatergic synapses measured in vitro. Results from these studies will fill an important gap in our knowledge and will define the actions of toluene on key elements of the addiction neurocircuitry.

Public Health Relevance

Abused inhalants are an important class of drugs of abuse that have received relatively little attention with respect to their mechanisms of action. Research to be carried out in this proposal will provide a detailed analysis of the effects of abused inhalants on neurons within brain areas involved in addiction.

Agency
National Institute of Health (NIH)
Institute
National Institute on Drug Abuse (NIDA)
Type
Research Project (R01)
Project #
5R01DA013951-10
Application #
8420263
Study Section
Special Emphasis Panel (ZRG1-IFCN-A (02))
Program Officer
Purohit, Vishnudutt
Project Start
2001-04-01
Project End
2014-12-31
Budget Start
2013-01-01
Budget End
2014-12-31
Support Year
10
Fiscal Year
2013
Total Cost
$301,177
Indirect Cost
$86,800
Name
Medical University of South Carolina
Department
Neurosciences
Type
Schools of Medicine
DUNS #
183710748
City
Charleston
State
SC
Country
United States
Zip Code
29425
Wayman, Wesley N; Woodward, John J (2018) Exposure to the Abused Inhalant Toluene Alters Medial Prefrontal Cortex Physiology. Neuropsychopharmacology 43:912-924
Gioia, Dominic A; Xu, Minfu; Wayman, Wesley N et al. (2018) Effects of drugs of abuse on channelrhodopsin-2 function. Neuropharmacology 135:316-327
Wayman, Wesley N; Woodward, John J (2018) Chemogenetic Excitation of Accumbens-Projecting Infralimbic Cortical Neurons Blocks Toluene-Induced Conditioned Place Preference. J Neurosci 38:1462-1471
Braunscheidel, K M; Gass, J T; Mulholland, P J et al. (2017) Persistent cognitive and morphological alterations induced by repeated exposure of adolescent rats to the abused inhalant toluene. Neurobiol Learn Mem 144:136-146
Beckley, Jacob T; Randall, Patrick K; Smith, Rachel J et al. (2016) Phenotype-dependent inhibition of glutamatergic transmission on nucleus accumbens medium spiny neurons by the abused inhalant toluene. Addict Biol 21:530-46
Nimitvilai, Sudarat; You, Chang; Arora, Devinder S et al. (2016) Differential Effects of Toluene and Ethanol on Dopaminergic Neurons of the Ventral Tegmental Area. Front Neurosci 10:434
Mahler, Stephen V; Vazey, Elena M; Beckley, Jacob T et al. (2014) Designer receptors show role for ventral pallidum input to ventral tegmental area in cocaine seeking. Nat Neurosci 17:577-85
Woodward, John J; Beckley, Jacob (2014) Effects of the abused inhalant toluene on the mesolimbic dopamine system. J Drug Alcohol Res 3:
Cruz, Silvia L; Rivera-García, María Teresa; Woodward, John J (2014) Review of toluene action: clinical evidence, animal studies and molecular targets. J Drug Alcohol Res 3:
Beckley, Jacob T; Woodward, John J (2013) Volatile solvents as drugs of abuse: focus on the cortico-mesolimbic circuitry. Neuropsychopharmacology 38:2555-67

Showing the most recent 10 out of 17 publications