Research reportE2-BSA and G1 exert neuroprotective effects and improve behavioral abnormalities following traumatic brain injury: The role of classic and non-classic estrogen receptors
Introduction
Permanent disability or death following traumatic brain injury (TBI) has become a public health concern over recent decades. TBI leads to pathophysiological changes that subsequently initiate diffuse secondary insults in the injured tissues (O’connor et al., 2011). Oxidative stress, increased inflammatory response, blood–brain barrier (BBB) damage, edema formation, increased intracranial pressure (ICP), and decreased cerebral perfusion pressure (CPP) are symptoms of secondary injury, which consequently reduce cerebral blood flow and induce brain ischemia (Unterberg et al., 2004, Gabrielian et al., 2011).
It is well known that the pathological changes caused by mechanical forces to the brain can lead to sensorimotor deficits (Soltani et al., 2015). In addition to locomotor dysfunctions, TBI survivors suffer from cognitive impairments and mood disorders (Hyder et al., 2007). Cognitive dysfunctions, including the impaired speed of information processing, poor memory, executive problems, and thought and reasoning difficulties are the most frequent detrimental neurobiological consequences of TBI (Fleminger, 2008). It has been shown that these disruptions in memory are associated with increased anxiety levels (Baykara et al., 2013).
It has been previously demonstrated that 17β-estradiol (E2) can reduce brain edema, ICP and BBB damage (Maghool et al., 2013), apoptosis (Soustiel et al., 2005), pro-inflammatory cytokines' levels (Sarkaki et al., 2011), and cortical contusion volumes (Bramlett and Dietrich, 2001). In addition, E2 can increase CPP and neurological scores (Hajmohammadi et al., 2019). These studies have also demonstrated that the neuroprotective effects of E2 are carried out via E2 interaction with classical receptors, including intracellular estrogen receptor-α (ERα) and estrogen receptor-β (ERβ), which trigger the genomic pathway (Dehghan et al., 2015). Blocking the genomic pathway using the estrogen classical receptors antagonist (ICI 182780) suggests that classical estrogen receptors are involved in the neuroprotective effects of E2 following brain injury (Sawada et al., 2000).
In addition to genomic responses, E2 has rapid non-genomic actions via the interaction of E2 with novel G-protein-coupled estrogen receptor (GPER, formerly known as GPR30) and membrane-associated ERα and ERβ (Alexander et al., 2017). Recent studies have demonstrated that GPER activation enhances the protection against brain injuries (Lu et al., 2016), while GPER selective antagonist reduces the neuroprotective effects of E2 (Gingerich et al., 2010, Roque et al., 2019). Elimination of E2 membrane permeability by using E2-BSA (E2 conjugated to bovine serum albumin) illustrated that non-genomic signaling pathways are activated by membrane receptors (Stevis et al., 1999).
It has been reported that E2 can inhibit the detrimental outcomes of TBI on cognition and anxiety levels in mice (Lu et al., 2018). Additionally, several studies have provided evidence that classic ERα and ERβ improve learning and memory and reduce anxiety-like behaviors (Raval et al., 2013, Handa et al., 2012). Furthermore, non-genomic signaling of E2 can enhance memory performance and improve mood disorders such as anxiety (Hadjimarkou and Vasudevan, 2018).
Previously, we have shown that E2 plays a neuroprotective role, in the short term after TBI (Dehghan et al., 2015). Therefore, the present study evaluated the effects of E2 on cognitive, locomotor activity, and anxiety-like behavior in the long-term. Besides, we used E2-BSA, G1 (GPER selective agonist), ICI, and G15 (GPER selective antagonist) to determine the role of classical and non-classic E2 receptors in mediating the effects of this hormone following TBI.
Section snippets
The effect of E2, E2-BSA, G1, and estrogen receptors antagonists on brain edema
Changes in brain water content (BWC) showed a significant difference between the groups (F15, 80 = 23.42, P < 0.001).Fig. 2 As shown in Fig. 3A, BWC was increased in the TBI, oil, DMSO, and PBS groups compared to the sham group (P < 0.001). BWC was decreased in the E2 (P < 0.001), E2-BSA (P < 0.001), and G1 (P < 0.05) groups compared to their vehicle groups. Moreover, BWC in the group receiving E2 was lower than in the G1 (P < 0.05) (Fig. 3B).
Fig. 3C illustrates the effects of E2, E2-BSA
Discussion
In the present study, the effects of different forms of E2 on post-traumatic behaviors such as sensorimotor, cognitive, and mood disorders, as well as the role of classic and non-classic estrogen receptors on the E2 neuroprotective effect were examined in OVX rats. The main findings are as follows: 1) The post-TBI administration of E2, E2-BSA, and G1 reduced brain edema and BBB disruption; 2) G1 and all forms of E2 reduced ICP and increased CPP after TBI; 3) they improved memory and
Animals
Adult female Wistar rats were caged in a photoperiod-controlled room (12-h light/dark cycle) with a temperature of 22 ± 2 °C. Food and water were available ad libitum. All the experimental procedures were carried out under the approval of the Animal Research Ethics Committee of Kerman University of Medical Sciences (Ethical code: IR.KMU.REC.1396.1540).
Bilateral ovariectomy
After two-week acclimation, bilateral ovariectomy was performed under general anesthesia with an intraperitoneal injection of ketamine (80 mg/kg)
CRediT authorship contribution statement
Ladan Amirkhosravi: Formal analysis, Investigation, Software, Writing - original draft. Mohammad Khaksari: Conceptualization, Data curation, Project administration, Writing - review & editing, Supervision. Zahra Soltani: Methodology, Formal analysis. Saeed Esmaeili-Mahani: Methodology, Data curation, Visualization. Gholamreza Asadi Karam: Methodology, Project administration. Mojtaba Hoseini: Investigation.
Declaration of Competing Interest
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
Acknowledgment
The present study was financially supported by the Physiology Research Center of Kerman University of Medical Sciences (Kerman, Iran).
References (79)
- et al.
Emerging roles for the novel estrogen-sensing receptor GPER1 in the CNS
Neuropharmacology
(2017) - et al.
17Beta-estradiol differentially protects cortical pericontusional zone from programmed cell death after traumatic cerebral contusion at distinct stages via non-genomic and genomic pathways
Mol. Cell. Neurosci.
(2011) - et al.
Modulatory effects of the basolateral amygdala α2-adrenoceptors on nicotine-induced anxiogenic-like behaviours of rats in the elevated plus maze
Neuropharmacology
(2016) - et al.
Neuroprotection in Parkinsonian-treated mice via estrogen receptor α activation requires G protein-coupled estrogen receptor 1
Neuropharmacology
(2015) - et al.
Why estrogens matter for behavior and brain health
Neurosci. Biobehav. Rev.
(2017) - et al.
Estrogen receptor alpha and G-protein coupled receptor 30 mediate the neuroprotective effects of 17β-estradiol in novel murine hippocampal cell models
Neuroscience
(2010) - et al.
GPER1/GPR30 in the brain: Crosstalk with classical estrogen receptors and implications for behavior
J. Steroid Biochem. Mol. Biol.
(2018) - et al.
GPR30 is positioned to mediate estrogen effects on basal forebrain cholinergic neurons and cognitive performance
Brain Res.
(2011) - et al.
Chronic treatment with estrogen receptor agonists restores acquisition of a spatial learning task in young ovariectomized rats
Horm. Behav.
(2009) - et al.
Chronic treatment with a GPR30 antagonist impairs acquisition of a spatial learning task in young female rats
Horm. Behav.
(2012)
Activation of the G-protein coupled receptor 30 (GPR30) has different effects on anxiety in male and female mice
Steroids
Effects of sex steroid hormones and their metabolites on neuronal injury caused by oxygen-glucose deprivation/reoxygenation in organotypic hippocampal slice cultures
Steroids
Membrane estrogen receptors: Genomic actions and post transcriptional regulation
Mol. Cell. Endocrinol.
The brain cytokine levels are modulated by estrogen following traumatic brain injury: Which estrogen receptor serves as modulator?
Int. Immunopharmacol.
Changes in the gene expression of estrogen receptors involved in the protective effect of estrogen in rat׳s trumatic brain injury
Brain Res.
Activation of G protein-coupled estrogen receptor 1 (GPER-1) ameliorates blood-brain barrier permeability after global cerebral ischemia in ovariectomized rats
Biochem. Biophys. Res. Commun.
Hippocampal cytosolic estrogen receptors regulate fear generalization in females
Neurobiol. Learn. Mem.
Estrogen protects the blood-brain barrier from inflammation-induced disruption and increased lymphocyte trafficking
Brain. Behav. Immun.
Differences in brain edema and intracranial pressure following traumatic brain injury across the estrous cycle: involvement of female sex steroid hormones
Brain Res.
Dissociable involvement of estrogen receptors in perirhinal cortex-mediated object-place memory in male rats
Psychoneuroendocrinology
Effects of estrogen receptor GPR30 agonist G1 on neuronal apoptosis and microglia polarization in traumatic brain injury rats
Chinese J. Traumatol.
The role of G protein-coupled estrogen receptor 1 on neurological disorders
Front. Neuroendocrinol.
Activation of classical estrogen receptor subtypes reduces tight junction disruption of brain endothelial cells under ischemia/reperfusion injury
Free Radic. Biol. Med.
Reprint of ”GPR30 mediates estrogen rapid signaling and neuroprotection”
Mol. Cell. Endocrinol.
Edema and brain trauma
Neuroscience
Magnesium attenuates persistent functional deficits following diffuse traumatic brain injury in rats
Neurosci. Lett.
Evaluation of estrous cycle stage and gender on behavioral outcome after experimental traumatic brain injury
Brain Res.
Activation of GPR30 attenuates diastolic dysfunction and left ventricle remodelling in oophorectomized mRen2.Lewis rats
Cardiovasc. Res.
GPER1 mediates estrogen-induced neuroprotection against oxygen-glucose deprivation in the primary hippocampal neurons
Neuroscience
Is inflammatory pulpal pain a risk factor for amnesia?
Iran. J. Vet. Sci. Technol.
Estrogen modulates microglial inflammatory mediator production via interactions with estrogen receptor β
Endocrinology
Progesterone treatment decreases traumatic brain injury induced anxiety and is correlated with increased serum IGF-1 levels; Prefrontal cortex, amygdala, hippocampus neuron density; And reduced serum corticosterone levels in immature rats
Biotech. Histochem.
Neuropathological Protection after Traumatic Brain Injury in Intact Female Rats Versus Males or Ovariectomized Females
J. Neurotrauma
G-1 exerts neuroprotective effects through G protein-coupled estrogen receptor 1 following spinal cord injury in mice
Biosci. Rep.
17β-Estradiol Prevents Blood-brain Barrier Disruption Induced by VEGF
Horm. Metab. Res.
Cross-Sectional Association between Markers of Inflammation and Serum Sex Steroid Levels in the Postmenopausal Estrogen/Progestin Interventions Trial
J. Women’s Heal.
17 β -Estradiol Confers Protection after Traumatic Brain Injury in the Rat and Involves Activation of G Protein-Coupled Estrogen Receptor 1
J. Neurotrauma
The Effects of Estrogen Receptors’ Antagonist on Brain Edema, Intracranial Pressure and Neurological Outcomes after Traumatic Brain Injury in Rat
Iran. Biomed. J.
In vivo effects of a GPR30 antagonist
Nat. Chem. Biol.
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2022, Brain Research BulletinCitation Excerpt :Estrogen also lowers IL-6, IL-1β and enhances IL-1ra production after ischemia and inflammation (Cerciat et al., 2010). Progesterone can also reduce inflammatory cytokines after TBI, thereby reducing edema (Tang et al., 2015; Amirkhosravi, 2021). Our research has also shown that combination of estrogen and progesterone protected against TBI damage in female rats (Soltani et al., 2009).
The G protein-coupled estrogen receptor (GPER) regulates recognition and aversively–motivated memory in male rats
2021, Neurobiology of Learning and MemoryCitation Excerpt :The second injection was given 15 min after the first injection, and behavioral testing was carried out 30 min after the second injection. In a rat model of traumatic brain injury, neuroprotective effects of an i.p. injection of G1 at 50 μg/kg given 30 min after the insult were recently found, and an i.p. injection of G15 at 50 μg/kg blocked the neuroprotective effect induced by E2 (Amirkhosravi et al., 2021). Again in a rat model of traumatic brain injury, intravenous administration of G1 (100 mg/kg) 30 min postinjury led to a reduction of apoptosis and promotion of microglia polarization in the adult rat brain (Pan, Tang, Liu, Feng, & Wan, 2018).
Marijuana and β-estradiol interactions on spatial learning and memory in young female rats: Lack of role of the G protein-coupled estrogen receptor (GPR30)
2021, Life SciencesCitation Excerpt :Marijuana (60 mg/kg) was injected for 28 consecutive days [44]. E2 (1 mg/kg) [45], G-1 and G-15 (50 μg/kg) [29,46,47] were injected every 4 days for 28 days (to mimic the natural estrous cycle) [48]. The vehicle group received DMSO, and the control group received no drug.
The antidepressant and anxiolytic effect of GPER on translocator protein (TSPO) via protein kinase a (PKA) signaling in menopausal female rats
2021, Journal of Steroid Biochemistry and Molecular BiologyCitation Excerpt :Our former work hinted that the anxiety and depression in aged female rats were significantly relieved after the treatment of G-1 and estrogen [47]. A most recent research also claimed that E2 and G-1 could exert neuroprotective effect and alleviate anxiety in OVX rats [66]. In our case, GPER was decreased in hippocampus due to the estrogen withdraw by ovariectomy, additionally, suppression or deletion of GPER could induce depressive- or anxiety-like phenotypes in female animals compared to intact ones.