Decipher

We shall translate the impact of pain and depression in animals into a validated in vitro test system as the main purpose of the project. The identification of molecular responses to pain and/or depression in the nervous system will provide predictive in vitro system for drug testing in neuropathic pain. A two-step strategy will be pursued:
1. Identification of electrophysiological correlates for the common impact of pain and stress-induced depression on central functions in vivo.
Our strategy involves the application of stress and neuropathic pain in animal models. Behavioural tests in combination with analgesics and antidepressants enable the analysis of mechanisms specific for pain and depression and the understanding of molecular mechanisms common to both states. Subsequently, brain responses to analgesics and antidepressants will be monitored by in vivo electrophysiology. In vivo electrophysiological responses will be related to in vitro electrophysiological responses in phenotypic neuronal cultures, and will allow to develop and validate a predictive in vitro drug test systems.
2. Translation of the in vivo situation into a predictive in vitro surrogate model.
Neuronal cultures are not prone to emotional stress or pain as in the case of animals which is a major obstacle for the development of predictive in vitro test systems. We shall overcome this problem by the introduction of a valid surrogate which mirrors the in vivo situation in an in vitro setting.
BDNF expression and concomitant BDNF signalling play a pivotal role both in pain sensation and in depression-like behaviour. Therefore, specific induction of different states of BDNF signalling in the periphery (and central) (dorsal root ganglia/spinal cord co-culture) or in the central nervous system (hippocampus/gyrus dentatus co-culture) might be indicative for conditions of neuropathic pain and depression.
To provide a surrogate model for pain-related mechanisms, we exploit RNAi-mediated knockdown of trkB receptor or overexpression of BDNF after lentiviral injection of expression vectors into (1) dorsal-root-ganglia/spinal cord in vivo/ dorsal-root-ganglia/spinal cord networks in vitro and (2) hippocampus/dentate gyrus in vivo/hippocampal/dentate gyrus networks in vitro. Additional application of drugs in combination with behavioural tests and in vivo electrophysiology will allow the identification of pain- and depression-related functional responses and neuronal network pattern changes. Such patterns will be compared to electrophysiological patterns obtained in primary neuronal neurons. The neuroregenerative results in vivo will be aligned with the behavioral ones, afterwards the electrophysiology results will be calibrated to both, the behavioral and neuroregenerative readouts and in vivo and in vitro electrophysiological models for pain/depression will be defined for their feasibility.