We believe that advances in understanding the pathophysiology of complex multifactorial diseases such as depression, addiction, and schizophrenia require a multidisciplinary approach. Our research group utilizes a variety of research techniques ranging from ex vivo electrophysiology, to functional anatomy, biochemistry, and animal behavior to tackle fundamental questions regarding the nature of psychiatric diseases.
We utilize whole-cell and field-potential electrophysiological recordings to study endocannabinoid-mediated synaptic signaling and plasticity in various brain regions. We are interested in how these signaling systems change in response to stress, and the relevance of these changes to the development of disease symptoms. We have state of the art electrophysiological equipment capable of fluorescent-guided patch-clamp, dual patch-clamp recordings, and focal micro-stimulation. (right) Voltage-clamp traces of a basolateral amygdala neuron demonstrating depolarization-induced suppression of inhibition (DSI), a well known form of endocannabinoid-mediated short-term synaptic signaling.
We use immunohistochemistry to describe the cellular and sub-cellular localization of proteins relevant to endocannabinoid signaling in different brain regions. We measure neuronal morphology using Golgi and intracellular trace fills to understand the role of endocannabinoid signaling in stress-induced morphological alterations. We utilize measurements of neuronal activity including early-immediate gene expression, combined with double or triple-labeled immunohistochemistry to identify distinct neuronal subtypes/circuits activated by various stimuli. We use chemical and electrolytic neuronal lesions to study functional connectivity relevant to stress adaptation.
We utilize stable isotope-dilution tandem LC/MS/MS to quantify endocannabinoid levels in brain micro-punches ~5 mg in wet tissue weight, or less. This system allows for high specificity and signal-to noise analysis, as well as relatively high trough-put. This technique is essential to the study of endocannabinoid neurophysiology and is conducted in collaboration with the Mass Spectrometry Core Facility at Vanderbilt University. (right) Targeted metabolome profiling of 2-AG. Chromatogram showing high signal-to -noise ratio of 2-AG, OAG and SAG- 2-AG precursors, and arachidonic acid- the primary metabolite of 2-AG catabolism. This sample is from a 1 mm micro-punch of the mouse basolateral amygdala.
Ultimately, we aim to understand how various synaptic, morphological, and physiological processes affect behavior. Behavioral data ultimately drives drug discovery and development and is a critical element to a translational research program. We utilize animal models of anxiety, depression, cognition, fear-learning and post-traumatic stress-disorder, as well as drug dependence to asses the viability of novel endocannabinoid-based pharmacological agents for the treatment of mental illness.