ABSTRACT
A rapid liquid chromatography/tandem mass spectrometry (LC-MS/MS) method has been developed for the measurement of dopamine (DA), 5-hydroxytryptamine (5HT) and norepinephrine (NE) in brain microdialysates. The assay has also been utilised for the simultaneous measurement of these neurotransmitters and cocaine in brain dialysates. The neurotransmitters and cocaine were resolved in a single 4-min run using a binary gradient elution profile. The analytes were detected using tandem mass spectrometry in the positive ion electrospray mode. The limits of detection for DA, NE, 5HT and cocaine were 200, 1000, 900 pM and 1 pg ml(-1), respectively.
Subject(s)
Biogenic Monoamines/analysis , Brain Chemistry , Chromatography, High Pressure Liquid/methods , Cocaine/analysis , Mass Spectrometry/methods , Animals , Brain Chemistry/drug effects , Chromatography, High Pressure Liquid/instrumentation , Cocaine/pharmacology , Extracellular Space/drug effects , Extracellular Space/metabolism , Linear Models , Male , Mass Spectrometry/instrumentation , Microdialysis/methods , Rats , Rats, Sprague-Dawley , Reproducibility of Results , Sensitivity and SpecificityABSTRACT
A high-throughput liquid chromatography/tandem mass spectrometry method has been developed for the quantitative assessment of 1-methyl-4-phenylpyridinium (MPP+) in brain tissue samples. This separation is based on reversed phase chromatography using formic acid and acetonitrile as the mobile phase. Using gradient separation conditions, MPP+ was resolved within 5 min and detected using tandem mass spectrometry in the positive ion electrospray mode. The limit of detection for MPP+ was found to be 1 fmol on column with a signal to noise ratio of 3:1. The assay has been used routinely in our laboratory for the measurement of MPP+ levels in brain tissue from 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-treated mice, and can be used to distinguish neuroprotective efficacy and monoamine oxidase inhibition.
Subject(s)
1-Methyl-4-phenylpyridinium/analysis , Brain/metabolism , Chromatography, High Pressure Liquid/methods , Mass Spectrometry/methods , 1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine/analysis , 1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine/chemistry , 1-Methyl-4-phenylpyridinium/chemistry , 1-Methyl-4-phenylpyridinium/toxicity , Animals , Antiparkinson Agents/pharmacology , Brain/cytology , Brain/drug effects , Brain Chemistry , Male , Mice , Reproducibility of Results , Selegiline/pharmacology , Sensitivity and Specificity , Time Factors , Tissue DistributionABSTRACT
Recent neuroanatomical and functional investigations focusing on dopamine (DA) D(3) receptors have suggested a potential role of this receptor in psychiatric diseases such as schizophrenia and drug dependence. In line with the key role of the prefrontal cortex in psychiatric disorders, the present study aimed at assessing the effects of the acute systemic administration of the selective DA D(3) receptor antagonist SB-277011-A on the in vivo extracellular levels of monoamines (DA, norepinephrine (NE), and serotonin (5-HT)) and acetylcholine (ACh) in the anterior cingulate subregion of the medial prefrontal cortex. The in vivo neurochemical profile of SB-277011-A (10 mg/kg, i.p.) in the anterior cingulate cortex was compared with both typical and atypical antipsychotics including clozapine (10 mg/kg, s.c.), olanzapine (10 mg/kg, s.c.), sulpiride (10 mg/kg, s.c.), and haloperidol (0.5 mg/kg, s.c.). The acute administration of SB-277011-A, clozapine, and olanzapine produced a significant increase in extracellular levels of DA, NE, and ACh without affecting levels of 5-HT. Sulpiride also significantly increased extracellular DA, but with a delayed onset over SB-277011-A, clozapine, and olanzapine. In contrast, haloperidol failed to alter any of the three monoamines and ACh in the anterior cingulate cortex. These findings add to a growing body of evidence suggesting a differentiation between typical and atypical antipsychotic drugs (APDs) in the anterior cingulate cortex and a role of DA D(3) receptors in desired antipsychotic drug profile. Similar to their effects on DA and NE, SB-277011-A, clozapine, and olanzapine increased extracellular levels of ACh, whereas haloperidol and sulpiride did not alter ACh. The results obtained in the present study provide evidence of the important role of DA D(3) receptors in the effect of pharmacotherapeutic agents that are used for the treatment of psychiatric disorders such as schizophrenia and drug dependence.
Subject(s)
Acetylcholine/metabolism , Biogenic Monoamines/metabolism , Dopamine D2 Receptor Antagonists , Gyrus Cinguli/metabolism , Tetrahydroisoquinolines , Animals , Gyrus Cinguli/drug effects , Male , Nitriles/pharmacology , Quinolines/pharmacology , Rats , Rats, Sprague-Dawley , Receptors, Dopamine D2/metabolism , Receptors, Dopamine D3ABSTRACT
A high-throughput liquid chromatography tandem mass spectrometry (LC/MS/MS) method has been developed for the analysis of acetylcholine (ACh) in brain dialysates. This separation of ACh is based on cation exchange chromatography with elution buffer consisting of a mixture of ammonium acetate, ammonium formate and acetonitrile. Using isocratic separation conditions, ACh was resolved within a minute and detected using tandem mass spectrometry in the positive ion electrospray mode. The limit of detection for ACh was found to be 1 fmol on column with a S/N ratio of 3:1. The assay has been used routinely for the measurement of ACh in brain dialysates from awake freely moving rats. Furthermore, separation conditions were modified to allow simultaneous measurement of ACh and the acetylcholine esterase inhibitor, neostigmine.
