Preclinical Analyses of the Therapeutic Potential of Allopregnanolone to Promote Neurogenesis In Vitro and In Vivo in Transgenic Mouse Model of Alzheimers Disease

Department of Molecular Pharmacology and Toxicology and Program in Neuroscience, Pharmaceutical Science Center, 1985 Zonal Avenue, University of Southern California, Los Angeles, CA 90033, USA.
Current Alzheimer Research (Impact Factor: 3.89). 03/2006; 3(1):11-7. DOI: 10.2174/156720506775697160
Source: PubMed


Herein, we present data to support a preclinical proof of concept for the therapeutic potential of allopregnanolone to promote neurogenesis. Our recent work has demonstrated that the neuroactive progesterone metabolite, allopregnanolone (3alpha-hydroxy-5alpha-pregnan-20-one), (APalpha) induced, in a dose dependent manner, a significant increase in proliferation of neuroprogenitor cells (NPCs) derived from the rat hippocampus and human neural stem cells (hNSM) derived from the cerebral cortex [1]. Proliferative efficacy was determined by incorporation of BrdU and (3)H-thymidine, FACS analysis of MuLV-GFP-labeled mitotic NPCs and quantification of total cell number. Allopregnanolone-induced proliferation was isomer and steroid specific, in that the stereoisomer 3beta-hydroxy-5beta-pregnan-20-one and related steroids did not increase (3)H-thymidine uptake. Immunofluorescent analyses for the NPC markers, nestin and Tuj1, indicated that newly formed cells were of neuronal lineage. Furthermore, microarray analysis of cell cycle genes and real time RT-PCR and western blot validation revealed that allopregnanolone increased the expression of genes which promote mitosis and inhibited the expression of genes that repress cell proliferation. Allopregnanolone-induced proliferation was antagonized by the voltage gated L-type calcium channel blocker nifedipine consistent with the finding that allopregnanolone induces a rapid increase in intracellular calcium in hippocampal neurons via a GABA type A receptor activated L-type calcium channel. Preliminary in vivo data indicate that APalpha for 24 hrs significantly increased neurogenesis in dentate gyrus, as determined by unbiased stereological analysis of BrdU positive cells, of 3-month-old male triple transgenic Alzheimer's disease mice. The in vitro and in vivo neurogenic properties of APalpha coupled with a low molecular weight, easy penetration of the blood brain barrier and lack of toxicity, are key elements required for developing APalpha as a neurogenic / regenerative therapeutic for restoration of neurons in victims of Alzheimer's disease.

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    • "In this regard, several laboratories have supported the protective, promyelinating and anti-inflammatory effects of progesterone and derivatives for experimental neuropathologies. These include spinal cord and brain trauma, ischemic stroke, diabetes mellitus, glutamate and b-amyloid toxicity, neuropathic pain, Alzheimer-like degeneration and neuro-inflammation (Brinton and Wang, 2006; Kaur et al., 2007; Leonelli et al., 2007; Labombarda et al., 2011; Coronel et al., 2011; Liu et al., 2012; De Nicola et al., 2013; Stein, 2013; Garay et al., 2014; Guennoun et al., 2015). In the nervous system, progesterone signaling is multifactorial, ranging from genomic effects after binding to nuclear receptors (PR), interaction of progesterone or its ring A-reduced metabolites with membrane progesterone receptors (mPR), modulation of neurotransmitter and opioid sigma receptors and binding to the progesterone receptor membrane component 1 (PRMC1) (Brinton et al., 2008; Petersen et al., 2013; Schumacher et al., 2014). "
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    ABSTRACT: The anti-inflammatory effects of progesterone have been increasingly recognized in several neuropathological models, including spinal cord inflammation. In the present investigation, we explored the regulation of proinflammatory factors and enzymes by progesterone at several time points after spinal cord injury (SCI) in male rats. We also demonstrated the role of the progesterone receptor (PR) in inhibiting inflammation and reactive gliosis, and in enhancing the survival of oligodendrocyte progenitors cells (OPC) in injured PR knockout (PRKO) mice receiving progesterone. First, after SCI in rats, progesterone greatly attenuated the injury-induced hyperexpression of the mRNAs of interleukin 1β (IL1β), IL6, tumor necrosis factor alpha (TNFα), inducible nitric oxide synthase (iNOS) and cyclooxygenase 2 (COX-2), all involved in oligodendrocyte damage. Second, the role of the PR was investigated in PRKO mice after SCI, in which progesterone failed to reduce the high expression of IL1β, IL6, TNFα and IκB-α mRNAs, the latter being considered an index of reduced NF-κB transactivation. These effects occurred in a time framework coincident with a reduction in the astrocyte and microglial responses. In contrast to wild-type mice, progesterone did not increase the density of OPC and did not prevent apoptotic death of these cells in PRKO mice. Our results support a role of PR in: (a) the anti-inflammatory effects of progesterone; (b) the modulation of astrocyte and microglial responses and (c) the prevention of OPC apoptosis, a mechanism that would enhance the commitment of progenitors to the remyelination pathway in the injured spinal cord.
    Full-text · Article · Sep 2015 · The Journal of steroid biochemistry and molecular biology
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    • "Within the SGZ and SVZ in male and female 3xTgAD mice a decline in neurogenesis is correlated with age-related AD-like pathology progression (Brinton and Wang, 2006; Rodriguez et al., 2008, 2009; Wang et al., 2010). Our studies have demonstrated that Allo promoted neurogenesis in the hippocampal SGZ to reverse learning and memory deficits (Wang et al., 2010). "
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    ABSTRACT: Allopregnanolone (Allo), a neurosteroid, has emerged as a promising promoter of endogenous regeneration in brain. In a mouse model of Alzheimer’s disease, Allo induced neurogenesis, oligodendrogenesis, white matter generation and cholesterol homeostasis while simultaneously reducing β-amyloid and neuroinflammatory burden. Allo activates signaling pathways and gene expression required for regeneration of neural stem cells and their differentiation into neurons. In parallel, Allo activates systems to sustain cholesterol homeostasis and reduce β-amyloid generation. To advance Allo into studies for chronic human neurological conditions, we examined translational and clinical parameters: dose, regimen, route, formulation, outcome measures, and safety regulations. A treatment regimen of once per week at sub-sedative doses of Allo was optimal for regeneration and reduction in Alzheimer’s pathology. This regimen had a high safety profile following chronic exposure in aged normal and Alzheimer’s mice. Formulation of Allo for multiple routes of administration has been developed for both preclinical and clinical testing. Preclinical evidence for therapeutic efficacy of Allo spans multiple neurological diseases including Alzheimer’s, Parkinson’s, multiple sclerosis, Niemann-Pick, diabetic neuropathy, status epilepticus, and traumatic brain injury. To successfully translate Allo as a therapeutic for multiple neurological disorders, it will be necessary to tailor dose and regimen to the targeted therapeutic mechanisms and disease etiology. Treatment paradigms conducted in accelerated disease models in young animals have a low probability of successful translation to chronic diseases in adult and aged humans. Gender, genetic risks, stage and burden of disease are critical determinants of efficacy. This review focuses on recent advances in development of Allo for Alzheimer’s disease that have the potential to accelerate therapeutic translation for multiple unmet neurological needs.
    Full-text · Article · Jul 2014 · Frontiers in Cellular Neuroscience
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    • "Depending on the outcome variable of interest, allopregnanolone may be a more potent inducer of neuroprotection than progesterone (Djebaili et al., 2005; Sayeed and Stein, 2009). Interestingly, allopregnanolone also increases progenitor cell proliferation (Brinton and Wang, 2006; Wang et al., 2008). Importantly these two neurosteroids do not work through the same receptor. "
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    ABSTRACT: Traumatic brain injury (TBI) increases cell death in the hippocampus and impairs hippocampus-dependent cognition. The hippocampus is also the site of ongoing neurogenesis throughout the lifespan. Progesterone treatment improves behavioral recovery and reduces inflammation, apoptosis, lesion volume, and edema, when given after TBI. The aim of the present study was to determine whether progesterone altered cell proliferation and short-term survival in the dentate gyrus after TBI. Male Sprague-Dawley rats with bilateral contusions of the frontal cortex or sham operations received progesterone or vehicle at 1 and 6 h post-surgery and daily through post-surgery Day 7, and a single injection of bromodeoxyuridine (BrdU) 48 h after injury. Brains were then processed for Ki67 (endogenous marker of cell proliferation), BrdU (short-term cell survival), doublecortin (endogenous marker of immature neurons), and Fluoro-Jade B (marker of degenerating neurons). TBI increased cell proliferation compared to shams and progesterone normalized cell proliferation in injured rats. Progesterone alone increased cell proliferation in intact rats. Interestingly, injury and/or progesterone treatment did not influence short-term cell survival of BrdU-ir cells. All treatments increased the percentage of BrdU-ir cells that were co-labeled with doublecortin (an immature neuronal marker in this case labeling new neurons that survived 5 days), indicating that cell fate is influenced independently by TBI and progesterone treatment. The number of immature neurons that survived 5 days was increased following TBI, but progesterone treatment reduced this effect. Furthermore, TBI increased cell death and progesterone treatment reduced cell death to levels seen in intact rats. Together these findings suggest that progesterone treatment after TBI normalizes the levels of cell proliferation and cell death in the dentate gyrus of the hippocampus.
    Full-text · Article · Jun 2011 · Experimental Neurology
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