M.C. Gonzalez Deniselle

Effects of injury and progesterone treatment on progesterone receptor and progesterone binding protein 25‐Dx expression in the rat spinal cord

Progesterone provides neuroprotection after spinal cord injury, but the molecular mechanisms involved in this effect are not completely understood. In this work, expression of two binding proteins for progesterone was studied in intact and injured rat spinal cord: the classical intracellular progesterone receptor (PR) and 25‐Dx, a recently discovered progesterone membrane binding site. RT‐PCR was employed to determine their relative mRNA levels, whereas cellular localization and relative protein levels were investigated by immunocytochemistry. We observed that spinal cord PR mRNA was not up‐regulated by estrogen in contrast to what is observed in many brain areas and in the uterus, but was abundant as it amounted to a third of that measured in the estradiol‐stimulated uterus. In male rats with complete spinal cord transection, levels of PR mRNA were significantly decreased, while those of 25‐Dx mRNA remained unchanged with respect to control animals. When spinal cord‐injured animals received progesterone treatment during 72 h, PR mRNA levels were not affected and remained low, whereas 25‐Dx mRNA levels were significantly increased. Immunostaining of PR showed its intracellular localization in both neurons and glial cells, whereas 25‐Dx immunoreactivity was localized to cell membranes of dorsal horn and central canal neurons. As the two binding proteins for progesterone differ with respect to their response to lesion, their regulation by progesterone, their cellular and subcellular localizations, their functions may differ under normal and pathological conditions. These observations point to a novel and potentially important role of the progesterone binding protein 25‐Dx after injury of the nervous system and suggest that the neuroprotective effects of progesterone may not necessarily be mediated by the classical progesterone receptor but may involve distinct membrane binding sites.

Progesterone and allopregnanolone in the central nervous system: response to injury and implication for neuroprotection.

Progesterone is a well-known steroid hormone, synthesized by ovaries and placenta in females, and by adrenal glands in both males and females. Several tissues are targets of progesterone and the nervous system is a major one. Progesterone is also locally synthesized by the nervous system and qualifies, therefore, as a neurosteroid. In addition, the nervous system has the capacity to bio-convert progesterone into its active metabolite allopregnanolone. The enzymes required for progesterone and allopregnanolone synthesis are widely distributed in brain and spinal cord. Increased local biosynthesis of pregnenolone, progesterone and 5α-dihydroprogesterone may be a part of an endogenous neuroprotective mechanism in response to nervous system injuries. Progesterone and allopregnanolone neuroprotective effects have been widely recognized. Multiple receptors or associated proteins may contribute to the progesterone effects: classical nuclear receptors (PR), membrane progesterone receptor component 1 (PGRMC1), membrane progesterone receptors (mPR), and γ-aminobutyric acid type A (GABAA) receptors after conversion to allopregnanolone. In this review, we will succinctly describe progesterone and allopregnanolone biosynthetic pathways and enzyme distribution in brain and spinal cord. Then, we will summarize our work on progesterone receptor distribution and cellular expression in brain and spinal cord; neurosteroid stimulation after nervous system injuries (spinal cord injury, traumatic brain injury, and stroke); and on progesterone and allopregnanolone neuroprotective effects in different experimental models including stroke and spinal cord injury. We will discuss in detail the neuroprotective effects of progesterone on the nervous system via PR, and of allopregnanolone via its modulation of GABAA receptors.

Progesterone Protective Effects in Neurodegeneration and Neuroinflammation

Progesterone is a neuroprotective, promyelinating and anti‐inflammatory factor for the nervous system. Here, we review the effects of progesterone in models of motoneurone degeneration and neuroinflammation. In neurodegeneration of the Wobbler mouse, a subset of spinal cord motoneurones showed increased activity of nitric oxide synthase (NOS), increased intramitochondrial NOS, decreased activity of respiratory chain complexes, and decreased activity and protein expression of Mn‐superoxide dismutase type 2 (MnSOD2). Clinically, Wobblers suffered several degrees of motor impairment. Progesterone treatment restored the expression of neuronal markers, decreased the activity of NOS and enhanced complex I respiratory activity and MnSOD2. Long‐term treatment with progesterone increased muscle strength, biceps weight and survival. Collectively, these data suggest that progesterone prevented neurodegeneration. To study the effects of progesterone in neuroinflammation, we employed mice with experimental autoimmune encephalomyelitis (EAE). EAE mice spinal cord showed increased mRNA levels of the inflammatory mediators tumour necrosis factor (TNF)α and its receptor TNFR1, the microglial marker CD11b, inducible NOS and the toll‐like receptor 4. Progesterone pretreatment of EAE mice blocked the proinflammatory mediators, decreased Iba1+ microglial cells and attenuated clinical signs of EAE. Therefore, reactive glial cells became targets of progesterone anti‐inflammatory effects. These results represent a starting point for testing the usefulness of neuroactive steroids in neurological disorders.

Progestins and antiprogestins: mechanisms of action, neuroprotection and myelination

Progesterone, originally considered as a hormone involved only in reproductive functions, exerts pleiotropic effects throughout the central and peripheral nervous systems. As early as 10 years ago, its role in myelination had been demonstrated in the regenerating peripheral nerve and in cocultures of neurons and Schwann cells. More recently, it has been shown that progesterone also accelerates myelin formation by oligodendrocytes in cerebellar organotypic cultures. Attention to the neuroprotective effects of progesterone was attracted at the end of the 1980s by the observation that female rats with high endogenous levels of progesterone recover better from traumatic brain injury and have less edema and secondary neuron loss than males. The protective effects of progesterone have been mainly studied in lesion models. However, progesterone also protects neurons from neurodegeneration, as has been documented in the Wobbler mouse, a murine model of spinal cord motoneuron degeneration. These findings have significant clinical implications, but an efficient therapeutic use of progestins for treating lesions or diseases of the nervous system would require a better understanding of their mechanisms of action in neurons and glial cells. We have indeed only a rudimentary understanding of the molecular mechanisms by which progestins exert their pleiotropic effects in the brain. Their study should provide a substantial basis for the design of progesterone analogs with much safer and selective actions. This review will summarize our current knowledge of the multiple mechanisms of progesterone action: the role of different progesterone receptor isoforms, the importance of coregulator proteins in modulating their transcriptional activities, and novel progesterone actions mediated by membrane receptors. The detailed account of the multiple mechanisms of progesterone action is followed by a discussion of recent studies, documenting the promyelinating and neuroprotective effects of progestins and offepristone (RU486), known as an antiprogestin or selective progesterone receptor modulator (SPRM). Their actions involve both classical and novel mechanisms.

Expression and cellular localization of the classical progesterone receptor in healthy and amyotrophic lateral sclerosis affected spinal cord

Previous studies have suggested that elevated progesterone levels are associated with a slower disease course in amyotrophic lateral sclerosis (ALS). Given that the effects of progesterone are mediated in part by the classical progesterone receptor (PR), the expression and cellular localization of the A and B isoforms (PR‐A and PR‐B, respectively) of the PR in control (neuropathologically normal) and ALS‐affected spinal cord (SC) were examined.

Potential Biomarkers with Plasma Cortisol, Brain-derived Neurotrophic Factor and Nitrites in Patients with Acute Ischemic Stroke

BACKGROUND Acute Ischemic Stroke (AIS) represents an economic challenge for health systems all over the globe. Changes of neuroactive steroids have been found in different neurological diseases. We have previously demonstrated that old patients with AIS show changes of plasma cortisol and estradiol concentrations, in that increased steroid levels are associated with a deterioration of neurological status and a worse cognitive decline. OBJECTIVE The present study assessed in patients with AIS if changes of behavior, Brain-Derived Neurotrophic Factor (BDNF) and Nitrites (NO-2) bear a relationship with the degree of hypercortisolism. METHODS We recruited patients hospitalized within the first 24 hours of AIS. Subjects were divided into two groups, each one composed of 40 control subjects and 40 AIS patients, including men and women. The neurological condition was assessed using the National Institute of Health Stroke Scale (NIHSS) and the cognitive status with the Montreal Cognitive Assessment (MoCA). The emotional status was evaluated using the Montgomery-Asberg Depression Rating Scale (MADRS), whereas the Modified Rankin Scale (MRS) was used to determine the functional condition. BDNF and NO-2 plasma levels were measured by ELISA and the Griess reaction method, respectively. RESULTS We found that in AIS patients, increased plasma cortisol was negatively correlated with plasma BDNF and NO-2 levels, neurological condition, cognition, functional responses and emotional status, suggesting a relationship between the declines of clinical, behavioral and blood parameters with stress-induced cortisol elevation. CONCLUSION Nitrites and BDNF may represent potential biomarkers for cortisol negative effects on the area of cerebral ischemia and penumbra, potentiating ischemic cell damage.

Experimental and clinical evidence for the protective role of progesterone in motoneuron degeneration and neuroinflammation

Abstract Far beyond its role in reproduction, progesterone exerts neuroprotective, promyelinating, and anti-inflammatory effects in the nervous system. These effects are amplified under pathological conditions, implying that changes of the local environment sensitize nervous tissues to steroid therapy. The present survey covers our results of progesterone neuroprotection in a motoneuron neurodegeneration model and a neuroinflammation model. In the degenerating spinal cord of the Wobbler mouse, progesterone reverses the impaired expression of neurotrophins, increases enzymes of neurotransmission and metabolism, prevents oxidative damage of motoneurons and their vacuolar degeneration (paraptosis), and attenuates the development of mitochondrial abnormalities. After long-term treatment, progesterone also increases muscle strength and the survival of Wobbler mice. Subsequently, this review describes the effects of progesterone in mice with induced experimental autoimmune encephalomyelitis (EAE), a commonly used model of multiple sclerosis. In EAE mice, progesterone attenuates the clinical severity, decreases demyelination and neuronal dysfunction, increases axonal counts, reduces the formation of amyloid precursor protein profiles, and decreases the aberrant expression of growth-associated proteins. These actions of progesterone may be due to multiple mechanisms, considering that classic nuclear receptors, extranuclear receptors, and membrane receptors are all expressed in the spinal cord. Although many aspects of progesterone action in humans remain unsolved, data provided by experimental models makes getting to this objective closer than previously expected.