In Vitro & In Vivo Electrophysiology Assays
Charles River offers a full range of in vitro and in vivo electrophysiology assays, including single cell recordings, brain slice electrophysiology, and patch clamp studies.
Figure 1: In Vivo Recording of Phasic Dopamine Release in Rodents
Dopamine concentration increase correlates to electrical stimulation intensity.
Case Study: Measuring Monoamine Levels in Prefrontal Cortex
The goal of the study was to understand how H3 antagonist/inverse agonist mediated an increase in monoamine levels (histamine and others) in the prefrontal cortex of freely moving rats and if this was the only mechanism to explain the increase in neurotransmitter levels.
A study combining data from microdialysis and single-unit recordings was designed. Microdialysis confirmed the observation that monoamine levels were increased in the prefrontal cortex. Single unit electrophysiological experiments in different brain areas were performed to see which neuronal pathway was involved.
The histamine H3 inverse agonist – thioperamide – was found to significantly increase the firing rate of DA neurons in the ventral tegmental area without affecting 5-HT neuron firing in the dorsal raphe nucleus or norepinephrine neuron firing in the locus coeruleus. Although the H3 inverse agonist affected DA cell firing, concomitant microdialysis demonstrated that all three neurotransmitters were elevated.
In Vivo Single Cell Recording
We can perform a variety of in vivo single-cell recording studies. This method is used to test the acute effect of a compound on an individual neuron or the effect of pre-treatment with a drug on the spontaneous firing activity and firing rate of multiple neurons. Neurons from various parts of the brain can be recorded, including:
Dopamine (substantia nigra and ventral tegmental area)
- Histamine (tuberomammillary nucleus)
- Norepinephrine (locus coeruleus)
- Glutamate pyramidal neurons (prefrontal cortex/hippocampus)
- Serotonin (medial raphe nucleus and dorsal raphe nucleus)
Long-term Potentiation (LTP)
We measure long-term potentiation both in vivo and in vitro from rat and mouse brains, including deficits induced by MK-801 or scopolamine.
Figure 2: Scopolamine Disrupted LTP
Electrophysiological measurement of scopolamine-induced disruption of long-term potentiation is shown.
In Vitro / Ex Vivo Patch Clamp
In vitro/ex vivo patch clamp recording allows the direct measurement of neuronal activity of a single cell or channel (receptor) and is also used to quantify synaptic inputs from excitatory and inhibitory circuits in tissue obtained from living animals. Some of the available patch clamp electrophysiology configurations include cell-attached, inside-out, whole cell, outside-out, and perforated patch.
Additionally, custom assays are available, including:
- H and M reflexes to assess lower back pain and spasticity
- Iontophoretic compound efficacy testing on neuronal firing