Browsing by Author "Wilson, Elizabeth"
Now showing 1 - 9 of 9
- Results Per Page
- Sort Options
Item Impact of sex and hypoxia on brain region-specific expression of androgen receptor AR45 and G protein Gαq in young adult rats(2024-03-21) Wilson, Elizabeth; Bradshaw, Jessica; Mabry, Steve; Shrestha, Pawan; Gardner, Jennifer; Cunningham, RebeccaPurpose: Sex differences in oxidative stress-associated cognitive decline are influenced by sex hormone levels. However, little is known regarding the expression of hormone receptors in brain regions associated with cognitive function. Notably, oxidative stress-associated neuronal cell death is exacerbated through testosterone signaling via membrane-associated androgen receptor AR45 and G protein Gαq. The objective of this study was to elucidate the expression of AR45 and Gαq in brain regions associated with cognitive function. Additionally, we investigated whether chronic intermittent hypoxia (CIH), an oxidative stressor with sex-specific effects, would modulate AR45 and Gαq expression. Methods: Adult male and female Sprague-Dawley rats were exposed to CIH or normoxia for 14 days. We quantified AR45 and Gαq protein expression in various cognition-associated brain regions [dorsal hippocampal CA1, CA3, DG, and entorhinal cortex (ETC)] via western blotting. For comparisons, AR45 and Gαq protein expression were also assessed in brain regions outside the hippocampal-ETC circuit [thalamus (TH) and striatum (STR)]. Results: The highest AR45 levels were expressed in the CA1 while the lowest expression was observed in the STR. The highest Gαq levels were expressed in the DG and ETC while the lowest expression was observed in the TH. We observed no effect of sex on AR45 or Gαq expression regardless of brain region assessed. Similarly, there was no effect of CIH on AR45 expression in any of the brain regions examined. However, CIH exposure increased Gαq expression only in the CA3 regardless of sex. Conclusions: Our findings reveal enrichment of AR45 and Gαq protein expression within the hippocampal-ETC circuit, which is vulnerable to oxidative stress and neurodegeneration during cognitive decline. Moreover, our data suggest the CA3 is the most vulnerable region to CIH-mediated oxidative stress. Overall, these findings were observed in both sexes, indicating that there are no observed sex differences in AR45 and Gαq expression or their modulation by CIH.Item Long-term effects of late gestational maternal hypoxic stress on mood disorders: Sex and age differences(2021) Mabry, Steve; Wilson, Elizabeth; Rybalchenko, Nataliya; Engelland, Rachel; Fadeyibi, Oluwadarasimi; Osikoya, Oluwatobiloba; Cushen, Spencer; Goulopoulou, Styliani; Cunningham, RebeccaPURPOSE: In utero insults have been linked with increased fear and anxiety in progeny. In utero hypoxic stress is also associated with multiple gestational complications. We hypothesized that exposure to maternal hypoxia during late gestation will have a long-term impact on anxiety in progeny. METHODS: Pregnant female Long-Evans rats were exposed to five days (gestational days: 15-20) of chronic intermittent hypoxia (CIH) or room air (normoxia: 21% O2) for 8 hours during their sleep phase. Each CIH cycle was 6 min of 3 min hypoxia (10% O2) and 3 min normoxia for a total of 10 CIH cycles/hour. At weaning (PND 28), progeny was pair-housed with a conspecific of same sex and similar weight. To examine anxiety disorders, we quantified anxiety-related behaviors (time spent in center of open field arena, marble burying test, social and anti-social behaviors with conspecifics) along with quantifying food intake and circulating sex hormone levels during puberty (postnatal day, PND 40-45) and young adulthood (PND 60-65) in male and female progeny. RESULTS: Maternal CIH did not impact circulating sex hormones or food intake, regardless of sex or age of progeny. However, maternal CIH increased anxiety related behaviors in pubertal females but were not observed in young adulthood. Maternal CIH did not impact male progeny, regardless of age. CONCLUSIONS: Maternal CIH during gestation resulted in increased anxiety related behaviors in pubertal female progeny. Maternal hypoxia during late gestation may temporarily increase the risk for anxiety disorders in pubertal females.Item Long-term effects of late gestational maternal hypoxic stress on neurodegeneration: Sex and age differences(2021) Wilson, Elizabeth; Mabry, Steve; Rybalchenko, Nataliya; Engelland, Rachel; Fadeyibi, Oluwadarasimi; Osikoya, Oluwatobiloba; Cushen, Spencer; Goulopoulou, Styliani; Cunningham, RebeccaIntroduction: In utero insults can lead to onset of neurodegenerative diseases, such as Parkinson's disease (PD). In utero hypoxic insults are associated with maternal sleep apnea or preeclampsia. It is unknown whether late gestational maternal hypoxic insults have long-term effects on brain regions associated with PD, such as the nigrostriatal pathway. We hypothesized that late gestational maternal hypoxia will result in sustained nigrostriatal impairment in male and female progeny. Methods: Timed pregnant Long-Evans rats were exposed to five days (gestational days: 15-20) of chronic intermittent hypoxia (CIH) or room air (normoxia 21% O2) for 8 hours during their sleep phase. Each CIH cycle was 6 min of alternating 3 min hypoxia (10% O2) and normoxia (21% O2) totaling 10 CIH cycles/hour. Gestational age and biometrics were recorded 12-16 hours after birth. At postnatal day, PND 28, progeny were pair-housed with a conspecific of the same sex and similar weight. We focused on PD associated oxidative stress and behavioral impairments in the nigrostriatal pathway. Gross motor (open field), fine motor (ultrasonic vocalizations), and cognition (spatial memory) were examined during puberty and young adulthood. Results: Maternal CIH had no effect on gestational age, progeny biometrics, or progeny circulating oxidative stress. Gross motor and cognitive functions were unaffected by maternal CIH. However, a sustained fine motor impairment was observed in both male and female progeny. Conclusion: Maternal hypoxia during late gestation induced sustained nigrostriatal pathway impairment, which may increase the risk for neurodegeneration.Item Long-term effects of prenatal chronic intermittent hypoxia insult on the substantia nigra(2021) Engelland, Rachel; Fadeyibi, Oluwadarasimi; Rybalchenko, Nataliya; Wilson, Elizabeth; Mabry, Steve; Osikoya, Oluwatobiloba; Cushen, Spencer; Goulopoulou, Styliani; Cunningham, RebeccaPurpose: Prenatal chronic intermittent hypoxia (CIH) was employed to evaluate the effects of hypoxic insults on the substantia nigra (SN), which is impacted by Parkinson's disease (PD). SN loss during PD is linked with oxidative stress (OS) and apoptosis. We hypothesized that exposure to late gestational maternal hypoxia would result in an increase in increased OS, but not apoptosis, in the SN of adult male and female progeny. Methods: During gestational days 15-20, pregnant Long-Evans rats were exposed to CIH or room air (normoxia) for 8 hours. CIH consisted of 3 min hypoxia (10% O2) and 3 min normoxia (21% O2). Animals were sacrificed at puberty (PND 44) or adulthood (PND 66). SN micropunches were obtained. OS was quantified by measuring calpain cleavage of spectrin. Results: OS (calpain cleavage of spectrin) was increased in the SN of adult male and female rats exposed to prenatal CIH compared to control (F1,17 = 3.606; p = 0.075). No effects on OS were observed in pubertal rats. Apoptosis (caspase-3 cleavage of spectrin) was not observed in any of the groups. Conclusions: These data suggest that prenatal CIH programming has a long-lasting impact on the SN of adult progeny, which may increase the susceptibility of SN to damage and PD risk. Although no sex differences were observed in this pilot study, we may see a sex effect upon increasing animal number, especially in male rats. This is consistent with the higher incidence of PD in men than in women.Item Mechanisms Underlying Membrane Androgen Receptor-Induced Neurodegeneration(2019-03-05) Duong, Phong; Wilson, Elizabeth; Cunningham, Rebecca; Tenkorang, MavisPurpose: A common characteristic of several neurodegenerative disorders is oxidative stress (OS). Many neurodegenerative disorders are more prevalent in men and postmenopausal women. Our lab has shown testosterone via a non-genomic mechanism exacerbates OS damage in neurons. Indeed, our lab was the first to discover the presence of the androgen receptor (AR) splice variant, AR45, in the brain. We found testosterone can initiate signaling cascades via this membrane associated AR (mAR), leading to increased OS. However, the mechanism for OS generation is unknown. NADPH Oxidase 1 and 2 (NOX 1/2) are major OS generators, and potential targets for androgen-induced OS and cell death. Based on our studies showing protein-protein interactions between NOX1/2, AR45 and Gαq, we hypothesize testosterone increases OS by activating mAR complexed with NOX 1/2, initiating IP3 signaling. Method: Using an immortalized neuronal cell line (N27 cells), we exposed cells to hydrogen peroxide (H2O2) prior to testosterone (100 nM) or DHT-BSA (500nM). Inhibitors were used to examine AR, IP3 and NOX1/2 signaling. Cell viability and OS were quantified. In addition to in vitro experiments, we examined the effects of NOX 1/2 on DHT exacerbation of chronic intermittent hypoxia, CIH (AHI=10) induced OS by treating adult male Long Evans rats with the NOX1/2 inhibitor, apocynin (4mg/kg). Results: Classical AR antagonists did not block testosterone’s negative effects, indicating classical AR does not mediate these effects. Since AR antagonists do not block mAR, we used an AR protein degrader, ASC-J9 (5uM). ASC-J9 blocked testosterone’s negative effects. Next, we examined signaling cascades associated with proteins complexed with mAR-AR45. To block NOX actions, we used apocynin (10 uM). Apocynin did not alter H2O2-induced cell loss, indicating H2O2 increases OS via a non-NOX mechanism. However, apocynin completely blocked testosterone induced cell loss and OS, suggesting the involvement of NOX1/2. Consistent with our in vitro data, apocynin also decreased OS generation in DHT-treated rats exposed to CIH, during sleep phase for 7 days. Inhibition of IP3 receptor blocked testosterone’s negative effects, indicating that testosterone may activate IP3 signaling via the mAR-NOX complex. Conclusion: NOX and IP3 play a crucial role in mAR-induced neurodegeneration. Future studies will examine the mAR-NOX complex as a therapeutic target for neurodegenerative diseases.Item Postpartum Maternal Vascular Function in a Rat Model of Gestational Obstructive Sleep Apnea(2020) Osikoya, Oluwatobiloba; Wilson, Elizabeth; Mabry, Steve; Cushen, Spencer; Cunningham, Rebecca; Goulopoulou, Styliani; Singhal, JuhiIntroduction: De novo obstructive sleep apnea (OSA) in pregnancy is associated with adverse gestational outcomes. In pregnant mice, exposure to chronic intermittent hypoxia (CIH), a model of OSA, induces endothelial dysfunction in maternal uterine arteries. It is currently unknown whether gestational OSA has a long-term effect on maternal vascular function. We hypothesized that exposure to gestational CIH during pregnancy will result in postpartum maternal vascular dysfunction. Methods: Pregnant rats were assigned to Normoxia and CIH groups. The CIH group was exposed to five days of intermittent hypoxia [6 min cycles of 3 min hypoxia (10% O2) and 3 min normoxia (21% O2)]. Endothelial function was assessed in isolated maternal uterine arteries at weaning (postnatal day 28). Vascular reactivity to acetylcholine (ACh) was examined in the presence and absence of uterine perivascular adipose tissue (PVAT) using wire myography. Results: In the absence of PVAT, uterine arteries from dams exposed to gestational CIH had exaggerated responses to ACh compared to dams exposed to normoxia [(-)PVAT/pEC50, Normoxia: 6.77±0.08 vs. CIH: 7.13±0.09, p< 0.01], while PVAT normalized this difference [(+)PVAT/pEC50, Normoxia: 6.67±0.08 vs. CIH: 6.70±0.07, p=0.99]. The effects of PVAT were due to its anti-dilatory influences on uterine arteries from CIH-treated rats ([CIH (-PVAT) vs. CIH (+PVAT), p = 0.003), whereas it had no effect on arteries from normoxic rats (p = 0.77). Conclusion: Exposure to gestational CIH exaggerated postpartum uterine vascular smooth muscle relaxation responses. Gestational OSA may impair maternal vascular recovery after birth.Item Sex Differences in Oxidative Stress Model of Prodromal Parkinson's Disease(2022) Mabry, Steve; Wilson, Elizabeth; Little, Joel; Romero, Steven; Cunningham, RebeccaINTRODUCTION: Parkinson's disease (PD) is an incurable neurodegenerative disorder that causes deterioration in motor and cognitive function and occurs more commonly in men. Gross motor impairment occurs after 60% dopaminergic neurons are lost in the substantia nigra brain region. However, it is unknown if sex differences are present in the prodromal stage of PD in which no dopaminergic neuronal loss or gross motor dysfunction are observed. Prodromal PD is associated with increased oxidative stress (OS) and OS damage in the substantia nigra, along with cognitive and fine motor skill dysfunction. To examine if sex differences are present in prodromal PD, we will use an animal model, chronic intermittent hypoxia (CIH), that recapitulates many prodromal PD characteristics. Our prior studies using male rats found that CIH induced global OS, OS damage in the substantia nigra, and cognitive dysfunction, which are all consistent with prodromal PD. METHODS: Adult male and female Sprague Dawley rats were exposed CIH to induce a prodromal PD phenotype. The CIH protocol consisted of 10 episodes of hypoxia (12% O2)/hour for a total of 8 hours/day over a 2-week period. Control rats were exposed to room air (normoxia). Rats were behaviorally tested for the following indexes during the last week of CIH exposure: 1) cognitive function (novel object recognition, Morris Water Maze), 2) fine motor behavior (modified open field with an elevated wire mesh), and 3) anxiety (marble test). At the conclusion of behavior testing, rats were sacrificed. Plasma and brain tissue was collected to examine oxidative stress. RESULTS: CIH increased circulating oxidized proteins in both male and female rats compared to control rats. No sex difference was observed in CIH induced circulating oxidative stress. Preliminary analysis indicate that sex differences are present in behavioral tests, especially cognitive function. CONCLUSIONS: These studies indicate sex differences in response to OS. CIH induced OS was consistent across both sexes, as evidenced by similar circulating OS levels. However, each sex responded (behaviorally) differently in response to CIH induced OS. These studies indicate that sex differences may be involved in prodromal PD. Knowledge of these sex differences could lead to earlier detection of PD and possibly the ability to slow conversion of prodromal PD to later stage PD that is exemplified by gross motor loss.Item Sex-dependent effects of chronic intermittent hypoxia: Implication for obstructive sleep apnea(2024-03-21) Mabry, Steve; Bradshaw, Jessica; Gardner, Jennifer; Wilson, Elizabeth; Cunningham, RebeccaBackground: Obstructive sleep apnea (OSA) is a highly prevalent sleeping disorder in the USA with known sex differences in prevalence and severity. Men have a higher incidence and experience greater severity of OSA than women. However, recent reports indicate the incidence of OSA in women, particularly mild cases of OSA, may be under-reported and left untreated. OSA is characterized by elevated oxidative stress and inflammation, mechanisms that involve mitochondrial function. This study addressed the role of 1) sex and 2) mitochondrial oxidative stress in OSA induced circulatory oxidative stress and inflammatory cytokines. Methods: Adult Sprague-Dawley male and female rats were implanted (s.c.) with an osmotic pump containing either MitoTEMPOL (mitochondrial oxidative stress inhibitor; MT) or saline vehicle and then exposed to a model of OSA, chronic intermittent hypoxia (CIH), or normoxic room-air for 14 days. The CIH protocol consisted of 10 CIH cycles/hour/8 hrs/day, in which each CIH cycle was composed of 3 minutes of normoxia at 21% O2 and 3 minutes of hypoxia at 10% O2. This protocol replicates an apnea-hypopnea index (AHI) of 10, which is consistent with mild OSA in humans. At the conclusion of the CIH protocol, rats were sacrificed and plasma was collected to quantify markers of oxidative stress (Advanced Oxidized Protein Products, AOPP) and inflammation (pro-inflammatory IL-6, anti-inflammatory IL-10, IL-6/IL-10 ratio). To determine statistical significance, ANOVA followed by Tukey’s post-hoc test was used. Significance level was set a p<0.05. Results: We found circulating oxidative stress was dependent on CIH and sex. Sex differences were observed in control normoxic rats, in which females had higher oxidative stress than males. Interestingly, the impact of CIH on oxidative stress was dependent on sex, wherein CIH decreased oxidative stress in females but increased oxidative stress in males. Inhibiting mitochondria-associated oxidative stress reduced oxidative stress in vehicle females, but only blocked the effect of CIH-induced oxidative stress in males. In contrast to oxidative stress, CIH increased the level of IL-6 only in females. Further, CIH overall induced a pro-inflammatory state as measured by an elevated IL6/IL10 ratio in females. The inflammatory effects of CIH in females were blocked by inhibiting mitochondrial-associated oxidative stress, despite no effect on circulating oxidative stress in CIH. Neither CIH nor MT impacted inflammatory markers in males. Discussion: These results indicate CIH-induced mechanisms underlying oxidative stress and inflammation are dependent on sex. Specifically, males experience a mitochondria-associated oxidative stress phenotype and females experience a mitochondria-associated inflammatory phenotype. These findings indicate that the OSA phenotype is sex-dependent, which may be related to the under-reported OSA incidence in women compared to men. Further, these data indicate that women may be at unique risk from OSA, particularly when AHIs are mild. Interestingly, inhibition of mitochondrial oxidative stress may be a potential drug target for both men and women with OSA.Item Testosterone Replacement Therapy: Role in Modulating Oxidative Stress within the Entorhinal Cortex(2021) Tajani, Ammaar; Cunningham, Rebecca; Rybalchenko, Nataliya; Wilson, ElizabethPurpose: Sleep apnea affects approximately a quarter of all Americans, with a higher incidence rate among men. Cognitive impairments are commonly observed. A rat model of sleep apnea, Chronic Intermittent Hypoxia (CIH), exhibits cognitive impairments associated with oxidative stress (OS). The entorhinal cortex (ETC) region of the brain is sensitive to OS and involved in cognition. Our studies show that Testosterone Replacement Therapy (TRT) can protect against CIH-induced circulating OS. However, it is unknown what the impact of TRT is on OS in the ETC. Methods: To address if TRT mitigates OS in the ETC, banked tissue from young adult male F344BN rats were exposed to normoxia (room air) or CIH (8-minute cycles of 5 minutes of 10% O2 and 3 minutes of 21% O2). Rats were gonadally intact, gonadectomized, or gonadectomized with TRT. OS was quantified by protein analysis of calpain cleavage of Spectrin and COX2. Since astrocytes can buffer OS, we quantified a marker of astrocytes (GFAP). Kruskal-Wallis non-parametric statistics were used. Results: Our prior results showed increased circulating OS in CIH exposed rats that were mitigated by TRT. Similarly, CIH increased OS in the ETC. However, astrocytes were increased only in TRT by CIH. Conclusion: This study suggests that TRT decreased OS by increasing astrocytes in the ETC. Astrocytes can play neuroprotective roles in the brain by buffering and neutralizing free radicals that lead to OS. TRT may be useful in preventing cognitive impairment associated with sleep apnea.