Neuroscience and Neurochemistry

Neuroactive compounds are synthetic analogues of neurosteroids that are naturally synthesized in the nervous tissue from cholesterol or steroidal precursors from peripheral sources. The neuroprotective effect of neurosteroids or neuroactive steroids is supposed to be realized via rapid, non-genomic mechanism. Multiple studies have been already performed to demonstrate efficacy of neurosteroids in the treatment of various central and peripheral nervous system diseases (e.g. ischemia, seizures, neurodegeneration, etc.). However, the mechanisms of neuroprotective effect of neuroactive steroids remain unclear and accumulating evidence indicate that this process can be regulated in multi-target manner. Moreover, neuroprotection include mechanisms protecting against neuronal injury/damage or degeneration according to acute or chronic origin of pathological process. As such, research targeting design and development of neuroprotective steroids with therapeutic potential is extremely challenging. In the last decade, we have synthesized a library of neuroactive steroids that act as potent negative modulators of N-methyl-D-aspartate receptors (NMDARs) that play significant role in learning and memory. Also, we have shown that these compounds do exhibit strong neuroprotective effect in in vivo models. Currently, our main avenue of investigation is development of an in vitro multiplexed screening platform to identify molecules with strong neuroprotective effect. Therefore, we have developed a methodology for neuroprotective effect screening in the model of glutamate/NMDA-induced excitotoxicity on embryonic cortex neurons. We conclude that pretreatment with our neurosteroids significantly reduced acute NMDA/L-glutamic acid excitotoxicity mediated by Ca²⁺ entry and consequent ROS release and caspase-3 activation. Compounds 6 (IC₅₀=5.8 µM), 7 (IC₅₀=12.2 µM), 9 (IC₅₀=7.8 µM), 13 (IC₅₀=1.1 µM) and 16 (IC₅₀=8.2 µM) attenuated glutamate-induced Ca²⁺ entry more effectively than memantine (IC₅₀=18.9 µM). Moreover, compound 13 was more effective than MK-801 (IC₅₀=1.2 µM). This drop in Ca²⁺ level resulted in corresponding reactive oxygen species suppression and prevented glutamate-induced caspase-3 activation.