Novel analogs of allopregnanolone show improved efficiency and specificity in neuroprotection and stimulation of proliferation

• Published in: Journal of neurochemistry 2016-12, Vol.139 (5), p.782-794
• Main Authors: Karout, Mona, Miesch, Michel, Geoffroy, Philippe, Kraft, Stephanie, Hofmann, Hans‐Dieter, Mensah‐Nyagan, Ayikoe Guy, Kirsch, Matthias
• Format: Article
• Language: English
• Subjects: allopregnanolone; Animals; Animals, Newborn; Cell culture; Cell Proliferation - drug effects; Cell Proliferation - physiology; Cells, Cultured; Dose-Response Relationship, Drug; hippocampus; Hippocampus - cytology; Hippocampus - drug effects; Hippocampus - physiology; Lateral Ventricles - cytology; Lateral Ventricles - drug effects; Lateral Ventricles - physiology; Life Sciences; Male; Mice; Mice, Inbred C57BL; neural stem cells; Neural Stem Cells - drug effects; Neural Stem Cells - physiology; Neurochemistry; neurogenesis; Neurological disorders; Neurons and Cognition; neuroprotection; Neuroprotective Agents - pharmacology; Pregnanolone - analogs & derivatives; Pregnanolone - pharmacology; Rats; Rats, Sprague-Dawley; Stem cells; β‐amyloid
• ISSN: 0022-3042; 1471-4159
• DOI: 10.1111/jnc.13693

The natural neurosteroid allopregnanolone exerts beneficial effects in animal models of neurodegenerative diseases, nervous system injury and peripheral neuropathies. It not only has anti‐apoptotic activity, but also promotes proliferation of progenitor cells. With respect to using it as a therapeutic tool, such pleiotropic actions might create unwanted side effects. Therefore, we have synthesized allopregnanolone analogs and analyzed their neuroprotective and proliferative effects to identify compounds with higher efficiency and less ambiguous biological actions. Proliferation‐promoting effects of 3α and 3β isomers of 3‐O‐allyl‐allopregnanolone and 12 oxo‐allopregnanolone were studied in adult subventricular zone stem cell cultures and in primary hippocampal cultures by measuring 5‐ethynyl‐2′‐deoxyuridine incorporation. Neuroprotective activity against amyloid beta 42‐induced cell death was determined by quantifying caspase 3/7 activity. The 3α isomers significantly stimulated proliferation in all culture systems, whereas the 3β isomers were ineffective. The stimulatory effect of 3α‐O‐allyl‐allopregnanolone was significantly higher than that of allopregnanolone. In neural stem cell cultures, 3α‐O‐allyl‐allopregnanolone specifically enhanced proliferation of Nestin‐positive progenitors. In addition, it promoted the differentiation of doublecortin‐positive neurons. In neural stem cell cultures treated with amyloid beta 42, both the α and β isomers of O‐allyl‐ allopregnanolone showed increased neuroprotective activity as compared to allopregnanolone, completely preventing amyloid‐induced caspase 3/7 activation. The 12 oxo‐allopregnanolone analogs were ineffective. These results identify structural allopregnanolone analogs with higher anti‐apoptotic and proliferation‐promoting activity than the natural neurosteroid. Interestingly, stereoisomers of the analogs were found to have distinct profiles of activity raising the possibility of exploiting the neuroprotective properties of neurosteroids with or without simultaneously stimulating neurogenesis. Cover Image for this issue: doi: 10.1111/jnc.13344. Neurosteroids synthesized in the nervous system are neuroprotective, anti‐apoptotic and promote cell proliferation. Such diverse biological actions may result in unwanted side effects, e.g., when neurosteroids would be used for treating neuropathic pain following cytostatic treatment. We have synthesized and tested analogs of the endogenous neurosteroid allopregnan