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Inflammations lead to the perturbation of aromatase enzyme
Inflammations lead to the perturbation of aromatase enzyme [112], which normally is responsible for a broad array of critical functions. Chemotherapy targets this enzyme, so this treatment option is never side-effect-free and not fully-effective. Therefore, the mankind should be careful so as not to breach the aromatase homeostasis. It will be an exciting area to probe other hither-to-unknown roles of aromatase. It will be interesting to find the equation of aromatase with other virulence and pathogenesis-related enzymes as glycosidase, protease, phospholipase etc. A lot of information pertaining aromatase needs to be pulled out.
Conclusions
Compliance with ethical standards
Introduction
Estrogen exerts a vast range of biological effects in the nervous system [1], [2]. Estrogen is reported to be neuroprotective in the brain, but there are few reports of such neuroprotection in spinal motor neurons, selectively involved in ALS. ALS is a devastating neurodegenerative disease that leads to loss of motor neurons in the cerebral cortex, brainstem, and spinal cord [3]. Clinical studies show that ALS occurs more commonly and earlier in men than women [4]. Consistent with the gender difference in humans, female SOD1 G93A transgenic mice exhibit a delayed disease onset vs males [5], while ovariectomy accelerates disease progression, an effect that can be reversed by prolonged estrogen treatment [6]. This evidence suggests that estrogen may play a protective role in ALS.
The enzyme aromatase (ARO) is responsible for estrogen synthesis and widely expressed in many sites, including TAME receptor [7], [8]. Synthesized estrogen targets two types of estrogen receptors(ER): classical nuclear receptors (ERα and ERβ) and novel cell membrane receptors (GPR30 and ER-X). Both ARO and ERs are expressed in peripheral nervous system and brain with cell- and tissue-specific distributions [9]. Research shows that ERs are expressed in neurons, and the neuroprotective activity of estrogen has mainly been related to a direct action on neurons [10].
Previous studies showed estrogen treatment was effective in improving locomotor function in spinal cord injury [11], [12], [13], [14] and ALS [4], [5], [6], [15], [16]. In vitro studies on motoneuron cell lines VSC4.1 and NSC-34 [17], [18], [19], [20], facial motoneurons [21] and isolated primary spinal cord motoneurons [22], [23] demonstrated estrogen was neuroprotective. However, distribution of ARO and ERs in motoneurons is inconsistent and controversial.
Materials and methods
Results
The results showed that the distribution profile of ERs and ARO in the spinal cord was similar in the adult male (n=4) and female (n=4) mice. Results described below were from adult male mice and the female results were in the supplemented meterial.
Discussion
Besides sexual differentiation and reproductive physiology and behavior, estrogen plays an important role in anti-inflammatory [24], anti-oxidative [25], anti-apoptotic [26] and other neuroprotective effects in neurodegenerative diseases, such as Alzheimer disease(AD) [27], Parkinson’s disease(PD) [28], ALS [4], [5], [6], [15], [16], [29], stroke [30], inflammatory diseases, such as multiple sclerosis(MS) [31], and brain and spinal cord injuries [11], [12], [13], [14], [32], [33], [34]. As ALS is one of the most common motor neuron disease, our laboratory mainly engaged in the research of ALS by SOD1G93Amice. So we background this paper on ALS and study their expression in normal mice spinal motor neuron.
Previous studies have implicated that aromatase expressed in the brain may confer neuroprotection by an array of mechanisms involving deceleration of degeneration and acceleration of repair [35].Previous research showed that in adult Japanese Quail, ARO-immunoreactive cells were located mostly in spinal cord lamina I–III, with additional sparse cells being present in the medial part of lamina V and in lamina X [36]. These data demonstrated that spinal aromatase ensured a local source of estrogens, but they did not detect aromatase-immunoreactive cells in the rat and Quail spinal cord ventral horn [36], [37], [38], [39]. However, embryonic rat spinal cord motor neurons express ARO [40] as is shown in our study. We found aromatase-immunoreactive cells located predominantly in ventral horn, that were characterized by large polygonal shapes, coincident with motoneurons. To verify the reliability, we observed co-expression of SMI-32, an anti- Non-Phosphorylated Neurofilaments (npNF) antibody, and anti-ARO antibody, and demonstrated that motor neurons in the spinal cord ventral horn expressed ARO.