RenaSci

Rat Microdialysis

Microdialysis in Freely-moving Rats

 

RenaSci employs the powerful tool of intracerebral microdialysis in freely-moving rats to assess the mode of action and/or drug abuse liability of novel centrally-acting compounds. We have over fifteen years of experience of using this sophisticated technique to support drug development.

Rat microdialysis can be used to measure extracellular levels of a variety of neurotransmitters and neuromodulators in different brain regions (eg monoamines and their metabolites, glutamate, GABA and acetylcholine). Microdialysis can be performed in normal rats and in strains of animals modelling specific diseases such as spontaneously hypertensive rats to model attention deficit hyperactivity disorder.

Key features of our rat microdialysis service include :-

     •     Normal or genetically modified rats
     •     Single or dual probe studies in freely moving rats
     •     Compounds dosed po, ip, sc, iv or by localised reverse-dialysis
     •     Samples taken for up to 24 h following drug administration
     •     High sensitivity analysis by UHPLC and HPLC with electrochemical detection 
     •     State-of-the art ALEXYS™ analysis systems 
     •     Optional blood and tissue-sampling from parallel groups of rats to provide
            pharmacokinetic/pharmacodynamic data on brain neurotransmitter and drug levels
            and plasma drug levels

Neurotransmitters and metabolites can be detected down to the following levels :-

     •     Dopamine (40 pM); DOPAC (2 nM); HVA (2 nM)
     •     Noradrenaline (200 pM)
     •     5-HT or serotonin (100 pM); 5-HIAA (2 nM).
     •     Glutamate (8 nM)
     •     GABA (6 nM)
     •     Acetylcholine with cholinesterase inhibitors (1 nM)

Using our current HPLC methodology, we can now measure simultaneously dopamine, DOPAC, HVA, 5-HT, 5-HIAA and noradrenaline plus GABA and glutamate in the same microdialysis sample. This is a major step forwards enabling cost-effective analysis of the effects of drugs on extracellular levels of multiple neurotransmitters and their metabolites in the brains of freely-moving animals.

 

Simultaneous Measurement of GABA, Glutamate and Monoamines in a Single Microdialysate Sample

Simultaneous Measurement of GABA, Glutamate and Monoamines in a Single Microdialysate Sample

 

Thus,  dual probe microdialysis can be employed to measure dopamine, DOPAC, HVA, 5-HT, 5-HIAA, noradrenaline, GABA, glutamate and acetylcholine in the same animals. For example,  we have recently used dual probe microdialysis to investigate the effects of xanomeline and d-amphetamine, alone and in combination, on levels of the monoamines and their metabolites, GABA and glutamate in the nucleus accumbens and levels of acetylcholine in the prefrontal cortex. Key findings from this study are shown below.

Use of Microdialysis to Measure Dopamine Levels in the Nucleus Accumbens

Use of Microdialysis to Measure DOPAC Levels in the Nucleus Accumbens

Using Microdialysis to Measure HVA Levels in the Nucleus Accumbens

Using Microdialysis to Measure Acetylcholine Levels in the Prefrontal Cortex

 

Drug and Neurotransmitter Measurements in the Same Microdialysate Sample

 

RenaSci has recently joined forces with pharm-analyt, a fully-independent bioanalytical company based in Vienna/Baden, Austria, to offer our clients a new service - measurement of drug concentrations and neurotransmitter levels in the same microdialysate sample. 

Pharm-analyt was established in 1986. The company have been measuring small molecules and their metabolites in a variety of biological tissues for over 30 years. For this purpose, they employ state-of-the-art instrumentation including mass spectrometry technology. This enables them to quantify drug concentrations in minimal sample volumes (eg 2 µl microdialysate) with very high sensitivity.

For example, microdialysate samples from the study described above were sent to pharm-analyt for analysis and d-amphetamine concentrations were measured in the nucleus accumbens and prefrontal cortex in the animals treated with d-amphetamine 0.5 mg/kg sc.

The results show an excellent correlation between d-amphetamine concentrations and dopamine levels in the nucleus accumbens and a weaker though still strong relationship between d-amphetamine concentrations and acetylcholine levels in the prefrontal cortex.

The ability to measure both drug concentrations and neurotransmitter levels in the same microdialysate sample provides important information regarding the pharmacodynamic-pharmacokinetic properties of the drug. Plasma samples can be taken during microdialysis studies if required. Please enquire for further information.

 

Other examples of rat microdialysis studies are :-

Use of Microdialysis to Measure Dopamine Levels in the Striatum

 

Use of Microdialysis to Measure Noradrenaline Levels in the Frontal Cortex

Effect of Nicotine on Dopamine Levels in Rat Nucleus Accumbens

Effect of Nicotine on DOPAC Levels in the Rat Nucleus Accumbens

Effect of Nicotine on HVA Levels in the Rat Nucleus Accumbens

 

Use of Microdialysis to Measure 5-HT Levels in the Ventral Hippocampus

 

Please contact us with the neurotransmitters and brain regions of interest if you would like us to draw up a draft protocol and costings for a microdialysis study for you. All microdialysis studies include advice on experimental design, statistical analysis by a qualified statistician, fully audited data pack and written reports to regulatory standards if required.

 

Posters

 

Cheetham et al. 2007. The SH rat model of ADHD has profoundly different catecholaminergic responses to amphetamine’s enantiomers compared with Sprague-Dawleys. Program No. 386.14 Society for Neuroscience Meeting, San Diego, California, USA, 3rd-7th November 2007.

 

Eyerman et al. 2014. Combinations of buprenorphine and samidorphan modulate glutamatergic transmission in the medial prefrontal cortex and ventral hippocampus of male Wistar rats. Poster No. W189. Presented at the 53rd Annual Meeting of the American College of Neuropsychopharmacology (ACNP), Phoenix, Arizona, USA, 7th-11th December 2014.

 

Gill et al. 2016. Determination of the concentrations of d-amphetamine, neurotransmitters and various metabolites in microdialysates taken from the brains of freely-moving rats. Program No. 498.13. Presented at the Society for Neuroscience Meeting, San Diego, California, USA, 12th-16th November 2016. 

 

Heal et al. 2006. Characterisation of the catecholaminergic profiles of methyphenidate and its enantiomers in an animal model of ADHD by in vivo microdialysis. Program No. 97.4. Society for Neuroscience Meeting, Atlanta, Georgia, USA, 14th-18th October 2006.

 

Heal et al. 2007. A comparison using in vivo microdialysis of the catecholamine profiles of dexamphetamine and methylphenidate in an animal model of ADHD. Program No 386.7. Society for Neuroscience Meeting, San Diego, California, USA, 3rd-7th November 2007.

 

Heal et al. 2014. Monoaminergic interactions between lisdexamfetamine and duloxetine determined by dual-probe intracerebral microdialysis in freely-moving rats. Program No 517.15. Society for Neuroscience Meeting, Washington, DC, USA, 15th-19th November 2014.

 

Hutson et al. 2014. A dual-probe microdialysis investigation of the interaction between lisdexamfetamine and S-citalopram on CNS monoamines - evidence for synergistic augmentation of serotonin and dopamine efflux. Poster No 39. Presented at the Annual Meeting of the American Society of Clinical Psychopharmacology (ASCP, formerly NCDEU), Hollywood, Florida, USA, 16th-19th June, 2014.

 

Rowley et al. 2005a. Effects of HT-2157, a Galanin-3 receptor antagonist, on extracellular levels of 5-HT in various brain regions of freely-moving rats. Abstract No.167P. Proceedings of the BPS Winter meeting, London, UK, December 2005.

 

Rowley et al. 2005b.The HT-2157 induced increase in extracellular 5-HT levels in the frontal cortex of freely-moving rats is modulated by 5 HT1A receptors. Abstract No.165P. Proceedings of the BPS Winter meeting, London, UK, December 2005.

 

Rowley et al. 2015. Simultaneous determination of the effects of methamphetamine on GABA, glutamate and monoamines by microdialysis in the prefrontal cortex and hippocampus of rats.  Abstract No 553. Presented at the 77th Annual Scientific Meeting of the College on Problems of Drug Dependence (CPDD), Phoenix, Arizona, USA, 13th-18th June 2015.

 

Rowley et al. 2016. Comparison of Synaptech versus CMA probes for the quantification of extracellular acetylcholine, dopamine and its metabolites by cerebral microdialysis in freely-moving rats. Program No. 846.15. Presented at the Society for Neuroscience Meeting, San Diego, California, USA, 12th-16th November 2016. 


Schumann et al. 2014. Metadoxine - a novel synaptic transmission modulator with low abuse potential in development for attention-deficit hyperactivity disorder (ADHD). Progam No. 2.30. Presented at the 61st Annual Meeting of the American Academy of Child and Adolescent Psychiatry (AACAP), San Diego, California, USA, 20th-25th October, 2014.

 

Manuscripts

 

Heal et al. 2008. New perspectives from microdialysis studies in freely moving spontaneously hypertensive rats on the pharmacology of drugs for the treatment of ADHD. Pharmacol Biochem Behav 90: 184-197. [PubMed] 

 

Hutson et al. 2015. The effects in rats of lisdexamfetamine in combination with olanzapine on mesocorticolimbic dopamine efflux, striatal dopamine D2 receptor occupancy and stimulus generalization to a d-amphetamine cue .Neuropharmacology 101: 24-35. [PubMed]