[Saikosaponin a alleviates pentylenetetrazol-induced acute epileptic seizures in mouse models of depression by suppressing microglia activation-mediated inflammation].

OBJECTIVE: To explore the inhibitory effect of saikosonin a (SSa) on pentylenetetrazol-induced acute epilepsy seizures in a mouse model of depression and explore the mechanism mediating this effect. METHODS: Male C57BL/6J mouse models of depression was established by oral administration of corticosterone via drinking water for 3 weeks, and acute epileptic seizures were induced by intraperitoneal injection of a single dose of pentylenetetrazole. The effect of intraperitoneal injection of SSa prior to the treatment on depressive symptoms and epileptic seizures were assessed using behavioral tests, epileptic seizure grading and hippocampal morphology observation. ELISA was used to detect blood corticosterone levels of the mice, and RTqPCR was performed to detect the pro- and anti-inflammatory factors. Microglia activation in the mice was observed using immunofluorescence staining. RESULTS: The mouse model of corticosterone-induced depression showed body weight loss and obvious depressive behaviors with significantly increased serum corticosterone level (all P < 0.05). Compared with those with pentylenetetrazole-induced epilepsy alone, the epileptic mice with comorbid depression showed significantly shorter latency of epileptic seizures, increased number, grade and duration of of seizures, reduced Nissl bodies in hippocampal CA1 and CA3 neurons, increased number of Iba1-positive cells, and significantly enhanced hippocampal expressions of IL-1ß, IL-10, TNF-α and IFN-γ. Pretreatment of the epileptic mice with SSa significantly prolonged the latency of epileptic seizures, reduced the number, duration, and severity of seizures, increased the number of Nissl bodies, decreased the number of Iba1-positive cells, and reduced the expression levels of IL-1ß, IL-10, TNF-α, and IFN-γ in the hippocampus (P < 0.05). CONCLUSION: Depressive state aggravates epileptic seizures, increases microglia activation, and elevates inflammation levels. SSA treatment can alleviate acute epileptic seizures in mouse models of depression possibly by suppressing microglia activation-mediated inflammation.

Comparison of pharmaceutical properties and biological activities of prednisolone, deflazacort, and vamorolone in DMD disease models.

Duchenne muscular dystrophy (DMD) is a progressive disabling X-linked recessive disorder that causes gradual and irreversible loss of muscle, resulting in early death. The corticosteroids prednisone/prednisolone and deflazacort are used to treat DMD as the standard of care; however, only deflazacort is FDA approved for DMD. The novel atypical corticosteroid vamorolone is being investigated for treatment of DMD. We compared the pharmaceutical properties as well as the efficacy and safety of the three corticosteroids across multiple doses in the B10-mdx DMD mouse model. Pharmacokinetic studies in the mouse and evaluation of p-glycoprotein (P-gP) efflux in a cellular system demonstrated that vamorolone is not a strong P-gp substrate resulting in measurable central nervous system (CNS) exposure in the mouse. In contrast, deflazacort and prednisolone are strong P-gp substrates. All three corticosteroids showed efficacy, but also side effects at efficacious doses. After dosing mdx mice for two weeks, all three corticosteroids induced changes in gene expression in the liver and the muscle, but prednisolone and vamorolone induced more changes in the brain than did deflazacort. Both prednisolone and vamorolone induced depression-like behavior. All three corticosteroids reduced endogenous corticosterone levels, increased glucose levels, and reduced osteocalcin levels. Using micro-computed tomography, femur bone density was decreased, reaching significance with prednisolone. The results of these studies indicate that efficacious doses of vamorolone, are associated with similar side effects as seen with other corticosteroids. Further, because vamorolone is not a strong P-gp substrate, vamorolone distributes into the CNS increasing the potential CNS side-effects.

Alcohol self-administration and nicotine withdrawal alter biomarkers of stress and inflammation and prefrontal cortex changes in Gß subunits.

Background: Although alcohol and nicotine are often used together, the biological consequences of these substances are not well understood. Identifying shared targets will inform cessation pharmacotherapies and provide a deeper understanding of how co-use of alcohol and nicotine impacts health, including biomarkers of stress and inflammation.Objective: We examined the effects of nicotine exposure and withdrawal on alcohol self-administration (SA), stress and inflammatory biomarkers, and a G-protein coupled receptor subunit (Gß) in brain areas associated with drug use.Methods: Male rats were trained to SA alcohol and then received a nicotine pump (n = 7-8 per group). We assessed alcohol intake for 12 days during nicotine exposure and then following pump removal to elicit withdrawal. After the behavioral studies, we assessed plasma leptin, corticosterone, and interleukin-1ß (IL-1ß), and Gß protein expression in the amygdala, nucleus accumbens (NAc), and prefrontal cortex (PFC).Results: Nicotine exposure or withdrawal did not alter alcohol intake (p > .05). Alcohol and nicotine withdrawal elevated corticosterone levels (p = .015) and decreased Gß levels in the PFC (p = .004). In the absence of nicotine, alcohol SA suppressed IL-1ß levels (p = .039). Chronic exposure to nicotine or withdrawal during alcohol SA did not alter leptin levels or Gß expression in the amygdala or NAc (p's > .05).Conclusions: The combination of alcohol SA and nicotine withdrawal produced a persistent increase in stress biomarkers and a suppression in Gß expression in the PFC, providing an important first step toward understanding the common biological mechanisms of alcohol/nicotine misuse.

Asthma: newer Tx options mean more targeted therapy.

It's an exciting era of asthma management, with the introduction of several novel modalities, including biological therapy and bronchial thermoplasty.

Simultaneous Fluorescence Imaging Reveals N-Methyl-d-aspartic Acid Receptor Dependent Zn2+/H+ Flux in the Brains of Mice with Depression.

Depression is immensely attributed to the overactivation of N-methyl-d-aspartic acid (NMDA) receptor in the brains. As regulatory binding partners of NMDA receptor, both Zn2+ and H+ are intimately interrelated to NMDA receptor's activity. Therefore, exploring synergistic changes on the levels of Zn2+ and H+ in brains will promote the knowledge and treatment of depression. However, the lack of efficient, appropriate imaging tools limits simultaneously tracking Zn2+ and H+ in living mouse brains. Thus, a well-designed dual-color fluorescent probe (DNP) was fabricated for the simultaneous monitoring of Zn2+ and H+ in the brains of mice with depression. Encountering Zn2+, the probe evoked bright blue fluorescence at 460 nm. Meanwhile, the red fluorescence at 680 nm was decreased with H+ addition. With blue/red dual fluorescence signal of DNP, we observed the synchronous increased Zn2+ and H+ in PC12 cells under oxidative stress. Notably, in vivo imaging for the first time revealed the simultaneous reduction of Zn2+ and pH in brains of mice with depression-like behaviors. Further results implied that the NMDA receptor might be responsible for the coinstantaneous fluctuation of Zn2+ and H+ during depression. Altogether, this work is conducive to the knowledge of neural signal transduction mechanisms, advancing our understanding of the pathogenesis in depression.

Corticosterone administration targeting a hypo-reactive HPA axis rescues a socially-avoidant phenotype in scarcity-adversity reared rats.

It is well-established that children from low-income, under-resourced families are at increased risk of altered social development. However, the biological mechanisms by which poverty-related adversities can "get under the skin" to influence social behavior are poorly understood and cannot be easily ascertained using human research alone. This study utilized a rodent model of "scarcity-adversity," which encompasses material resource deprivation (scarcity) and reduced caregiving quality (adversity), to explore how early-life scarcity-adversity causally influences social behavior via disruption of developing stress physiology. Results showed that early-life scarcity-adversity exposure increased social avoidance when offspring were tested in a social approach test in peri-adolescence. Furthermore, early-life scarcity-adversity led to blunted hypothalamic-pituitary-adrenal (HPA) axis activity as measured via adrenocorticotropic hormone (ACTH) and corticosterone (CORT) reactivity following the social approach test. Western blot analysis of brain tissue revealed that glucocorticoid receptor levels in the dorsal (but not ventral) hippocampus and medial prefrontal cortex were significantly elevated in scarcity-adversity reared rats following the social approach test. Finally, pharmacological repletion of CORT in scarcity-adversity reared peri-adolescents rescued social behavior. Our findings provide causal support that early-life scarcity-adversity exposure negatively impacts social development via a hypocorticosteronism-dependent mechanism, which can be targeted via CORT administration to rescue social behavior.

Therapeutic glucocorticoids prevent bone loss but drive muscle wasting when administered in chronic polyarthritis.

BACKGROUND: Patients with rheumatoid arthritis (RA) experience extra-articular manifestations including osteoporosis and muscle wasting, which closely associate with severity of disease. Whilst therapeutic glucocorticoids (GCs) reduce inflammation in RA, their actions on muscle and bone metabolism in the context of chronic inflammation remain unclear. We utilised the TNF-tg model of chronic polyarthritis to ascertain the impact of therapeutic GCs on bone and muscle homeostasis in the context of systemic inflammation. METHODS: TNF-tg and wild-type (WT) animals received either vehicle or the GC corticosterone (100 µg/ml) in drinking water at onset of arthritis. Arthritis severity and clinical parameters were measured, serum collected for ELISA and muscle and bone biopsies collected for µCT, histology and mRNA analysis. In vivo findings were examined in primary cultures of osteoblasts, osteoclasts and myotubes. RESULTS: TNF-tg mice receiving GCs showed protection from inflammatory bone loss, characterised by a reduction in serum markers of bone resorption, osteoclast numbers and osteoclast activity. In contrast, muscle wasting was markedly increased in WT and TNF-tg animals receiving GCs, independently of inflammation. This was characterised by a reduction in muscle weight and fibre size, and an induction in anti-anabolic and catabolic signalling. CONCLUSIONS: This study demonstrates that when given in early onset chronic polyarthritis, oral GCs partially protect against inflammatory bone loss, but induce marked muscle wasting. These results suggest that in patients with inflammatory arthritis receiving GCs, the development of interventions to manage deleterious side effects in muscle should be prioritised.

Neurologic complications of HTLV-1: a review / Complicações neurológicas do HTLV: uma revisão HTLV-1

The human T-cell lymphotropic virus type 1 (HTLV-1) is a retrovirus that infects about 20 million people worldwide and causes immune-mediated diseases of the nervous system. The classical neurological presentation of HTLV-1 infection is the so-called HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP). However, HAM/ TSP is not the only neurological outcome that can result from HTLV-1 infection. In this Review it is made an update on the many aspects of this important neurological condition, the HTLV-1 neurological complex.

O vírus linfotrópico de células T humanas tipo 1 (HTLV-1) é um retrovírus que infecta cerca de 20 milhões de pessoas em todo o mundo e causa doenças imunomediadas do sistema nervoso. A apresentação neurológica clássica da infecção pelo HTLV-1 é a chamada paraparesia espástica tropical / mielopatia associada ao HTLV-1 (HAM/TSP). HAM / TSP,no entanto, não é o único desfecho neurológico que pode resultar da infecção pelo HTLV-1. Nesta revisão, é feita uma atualização sobre vários aspectos desta importante condição neurológica, o complexo neurológico do HTLV-1.

Hyperadrenocorticism of calorie restriction contributes to its anti-inflammatory action in mice.

Calorie restriction (CR), which lengthens lifespan in many species, is associated with moderate hyperadrenocorticism and attenuated inflammation. Given the anti-inflammatory action of glucocorticoids, we tested the hypothesis that the hyperadrenocorticism of CR contributes to its attenuated inflammatory response. We used a corticotropin-releasing-hormone knockout (CRHKO) mouse, which is glucocorticoid insufficient. There were four controls groups: CRHKO mice and wild-type (WT) littermates fed either ad libitum (AL) or CR (60% of AL food intake), and three experimental groups: (a) AL-fed CRHKO mice given corticosterone (CORT) in their drinking water titrated to match the integrated 24-hr plasma CORT levels of AL-fed WT mice, (b) CR-fed CRHKO mice given CORT to match the 24-hr CORT levels of AL-fed WT mice, and (c) CR-fed CHRKO mice given CORT to match the 24-hr CORT levels of CR-fed WT mice. Inflammation was measured volumetrically as footpad edema induced by carrageenan injection. As previously observed, CR attenuated footpad edema in WT mice. This attenuation was significantly blocked in CORT-deficient CR-fed CRHKO mice. Replacement of CORT in CR-fed CRHKO mice to the elevated levels observed in CR-fed WT mice, but not to the levels observed in AL-fed WT mice, restored the anti-inflammatory effect of CR. These results indicate that the hyperadrenocorticism of CR contributes to the anti-inflammatory action of CR, which may in turn contribute to its life-extending actions.

Acute exogenous corticosterone treatments have few effects on courtship and pair bonding in zebra finches.

Stress impacts social relationships. In turn, social relationships buffer the stress response in some species. Studies that have investigated the role of corticosterone (CORT) on courtship, mate choice, mating, and pairing have found mixed results. We therefore tested the role of CORT in these steps of the pairing process in the monogamous zebra finch. Male and female zebra finches received either one of 2 doses of corticosterone (CORT, 10 µg and 20 µg, referred to as low and high dose) or a vehicle control (peanut oil). Subjects were then given the opportunity to pair in mixed sex aviaries. Courtship and pair bonding behaviors were observed over 3 days. Overall, zebra finches of both sexes were equally likely to pair or not pair regardless of treatment, although a high dose of CORT increased the latency to form a pair bond. There were no effects of CORT on courtship behavior in either sex, though the low dose increased undirected (non-courtship) singing in males relative to the high dose. Animals treated with CORT, regardless of dose, engaged in fewer copulations than did control animals. When we examined pairing behaviors, we found a decrease in co-nesting in low dose animals. Our results suggest that acute CORT has few effects on pair bonding, suggesting species-specific effects of CORT on behavior.

Sustained administration of corticosterone at stress-like levels after stroke suppressed glial reactivity at sites of thalamic secondary neurodegeneration.

Secondary neurodegeneration (SND) is an insidious and progressive condition involving the death of neurons in regions of the brain that were connected to but undamaged by the initial stroke. Our group have published compelling evidence that exposure to psychological stress can significantly exacerbate the severity SND, a finding that has considerable clinical implications given that stroke-survivors often report experiencing high and unremitting levels of psychological stress. It may be possible to use one or more targeted pharmacological approaches to limit the negative effects of stress on the recovery process but in order to move forward with this approach the most critical stress signals have to be identified. Accordingly, in the current study we have directed our attention to examining the potential effects of corticosterone, delivered orally at stress-like levels. Our interest is to determine how similar the effects of corticosterone are to stress on repair and remodelling that is known to occur after stroke. The study involved 4 groups, sham and stroke, either administered corticosterone or normal drinking water. The functional impact was assessed using the cylinder task for paw asymmetry, grid walk for sensorimotor function, inverted grid for muscle strength and coordination and open field for anxiety-like behaviour. Biochemically and histologically, we considered disturbances in main cellular elements of the neurovascular unit, including microglia, astrocytes, neurons and blood vessels using both immunohistochemistry and western blotting. In short, we identified that corticosterone delivery after stroke results in significant suppression of key microglial and astroglial markers. No changes were observed on the vasculature and in neuronal specific markers. No changes were identified for sensorimotor function or anxiety-like behaviour. We did, however, observe a significant change in motor function as assessed using the inverted grid walk test. Collectively, these results suggest that pharmacologically targeting corticosterone levels in the future may be warranted but that such an approach is unlikely to limit all the negative effects associated with exposure to chronic stress.

Influence of corticosterone treatment on nestling begging in Florida scrub-jays (Aphelocoma coerulescens).

Altricial young are dependent on adults for protection and food, and they display nutritional need by begging to elicit feeding from parents. Begging at high levels can be energetically expensive and attract predators; thus, an individual must balance its nutritional needs with these potential costs. Further, because a parent is limited in the amount of food it can provide, begging can contribute to both parent-offspring conflict and sibling-sibling competition. Many extrinsic and intrinsic factors may contribute to begging behavior. One intrinsic factor of interest is corticosterone (CORT), a metabolic hormone hypothesized to play a role in regulating a nestling's begging behavior. We investigated the hypothesis that increased exposure to CORT influences nestling begging behavior in an altricial species, the Florida scrub-jay (Aphelocoma coerulescens). We treated one nestling per treatment nest with a twice-daily dose of exogenous hormone via a CORT-injected waxworm, whereas a second individual received a vehicle-injected waxworm. We monitored individual nestling and adult behavior at all nests with the use of high-definition video cameras on several days during treatment. We found no difference in begging rate between CORT fed and vehicle fed nestlings within a treatment nest. Further, to determine whether CORT treatment had indirect effects on the entire brood, we monitored additional nests, in which nestlings were not manipulated. When treatment and controls were compared, overall begging rates of nestlings in treatment nests were greater than those in control nests. This result suggests that CORT treatment of an individual altered its behavior, as well as that of its siblings.

Chronic stress targets adult neurogenesis preferentially in the suprapyramidal blade of the rat dorsal dentate gyrus.

The continuous generation of new neurons and glial cells in the adult hippocampal dentate gyrus (DG) represents an important form of adult neuroplasticity, involved in normal brain function and behavior but also associated with the etiopathogenesis and treatment of psychiatric disorders. Despite the large number of studies addressing cell genesis along the septotemporal axis, data on the anatomical gradients of cytogenesis along the DG transverse axis is scarce, especially after exposure to stress. As such, in this study we characterized both basal proliferation and survival of adult-born neural cells along the transverse axis of the rat dorsal DG, and after stress exposure. In basal conditions, both proliferating cells and newborn neurons and glial cells were preferentially located at the subgranular zone and suprapyramidal blade. Exposure to chronic stress induced an overall decrease in the generation of adult-born neural cells and, more specifically, produced a regional-specific decrease in the survival of adult-born neurons at the suprapyramidal blade. No particular region-specific alterations were observed on surviving adult-born glial cells. This work reveals, for the first time, a distinct survival profile of adult-born neural cells, neurons and glial cells, among the transverse axis of the DG, in both basal and stress conditions. Our results unveil that adult-born neurons are preferentially located in the suprapyramidal blade and suggest a regional-specific impact of chronic stress in this blade with potential repercussions for its functional significance.

Safer topical treatment for inflammation using 5α-tetrahydrocorticosterone in mouse models.

Use of topical glucocorticoid for inflammatory skin conditions is limited by systemic and local side-effects. This investigation addressed the hypothesis that topical 5α-tetrahydrocorticosterone (5αTHB, a corticosterone metabolite) inhibits dermal inflammation without affecting processes responsible for skin thinning and impaired wound healing. The topical anti-inflammatory properties of 5αTHB were compared with those of corticosterone in C57Bl/6 male mice with irritant dermatitis induced by croton oil, whereas its effects on angiogenesis, inflammation, and collagen deposition were investigated by subcutaneous sponge implantation. 5αTHB decreased dermal swelling and total cell infiltration associated with dermatitis similarly to corticosterone after 24h, although at a five fold higher dose, but in contrast did not have any effects after 6h. Pre-treatment with the glucocorticoid receptor antagonist RU486 attenuated the effect of corticosterone on swelling at 24h, but not that of 5αTHB. After 24h 5αTHB reduced myeloperoxidase activity (representative of neutrophil infiltration) to a greater extent than corticosterone. At equipotent anti-inflammatory doses 5αTHB suppressed angiogenesis to a limited extent, unlike corticosterone which substantially decreased angiogenesis compared to vehicle. Furthermore, 5αTHB reduced only endothelial cell recruitment in sponges whereas corticosterone also inhibited smooth muscle cell recruitment and decreased transcripts of angiogenic and inflammatory genes. Strikingly, corticosterone, but not 5αTHB, reduced collagen deposition. However, both 5αTHB and corticosterone attenuated macrophage infiltration into sponges. In conclusion, 5αTHB displays the profile of a safer topical anti-inflammatory compound. With limited effects on angiogenesis and extracellular matrix, it is less likely to impair wound healing or cause skin thinning.

Oral Corticosterone Administration Reduces Insulitis but Promotes Insulin Resistance and Hyperglycemia in Male Nonobese Diabetic Mice.

Steroid-induced diabetes is the most common form of drug-induced hyperglycemia. Therefore, metabolic and immunological alterations associated with chronic oral corticosterone were investigated using male nonobese diabetic mice. Three weeks after corticosterone delivery, there was reduced sensitivity to insulin action measured by insulin tolerance test. Body composition measurements revealed increased fat mass and decreased lean mass. Overt hyperglycemia (>250 mg/dL) manifested 6 weeks after the start of glucocorticoid administration, whereas 100% of the mice receiving the vehicle control remained normoglycemic. This phenotype was fully reversed during the washout phase and readily reproducible across institutions. Relative to the vehicle control group, mice receiving corticosterone had a significant enhancement in pancreatic insulin-positive area, but a marked decrease in CD3+ cell infiltration. In addition, there were striking increases in both citrate synthase gene expression and enzymatic activity in skeletal muscle of mice in the corticosterone group relative to vehicle control. Moreover, glycogen synthase expression was greatly enhanced, consistent with elevations in muscle glycogen storage in mice receiving corticosterone. Corticosterone-induced hyperglycemia, insulin resistance, and changes in muscle gene expression were all reversed by the end of the washout phase, indicating that the metabolic alterations were not permanent. Thus, male nonobese diabetic mice allow for translational studies on the metabolic and immunological consequences of glucocorticoid-associated interventions in a mouse model with genetic susceptibility to autoimmune disease.

Ethanol Withdrawal-Induced Impaired Recognition Is Reversed by Chronic Exposure to Stress and the Acute Administration of Corticosterone in Mice.

The present study was designed to ascertain the effects of repeated exposure to stress and the acute administration of corticosterone (1, 3, 10 mg/kg, intraperitoneally (i.p.)) on the ethanol withdrawal-induced impairment of novel object recognition in mice. Mice were chronically treated with 3% ethanol for 7 d, with or without exposure to restraint stress for 1 h/d. A significant decrease in cognitive function was observed in the ethanol plus no stress group at 48 h after the discontinuation of ethanol treatment. This impaired recognition was recovered in the ethanol plus stress group. Moreover, we investigated the effects of acute pretreatment with corticosterone, which is a corticosteroid-type hormone produced in the cortex of the adrenal glands, on the impaired recognition after the discontinuation of ethanol treatment in mice. The impaired recognition in the 3% ethanol alone-treated group at 48 h after the discontinuation of ethanol treatment was recovered by treatment with the middle dose (3 mg/kg) of corticosterone, but not with the low or high doses (1, 10 mg/kg). These results suggest that chronic stress during the development of ethanol dependence may reduce the impaired recognition after the discontinuation of ethanol treatment. Moreover, acute pretreatment with the middle dose of corticosterone also recovered the impaired recognition after the discontinuation of ethanol treatment in mice. Adequate regulation of the hypothalamic-pituitary-adrenal (HPA) axis by corticosterone may improve the impaired recognition after the discontinuation of ethanol treatment.

Corticosteroids Mediate Heart Failure-Induced Depression through Reduced σ1-Receptor Expression.

Cardiovascular diseases are risk factors for depression in humans. We recently proposed that σ1 receptor (σ1R) stimulation rescued cardiac hypertrophy and heart failure induced by transverse aortic constriction (TAC) in mice. Importantly, σ1R stimulation reportedly ameliorates depression-like behaviors in rodents. Thus, we hypothesized that impaired σ1R activity in brain triggers depression-like behaviors in animals with cardiovascular disease. Indeed, here we found that cardiac hypertrophy and heart failure induced by TAC were associated with depression-like behaviors concomitant with downregulation of σ1R expression in brain 6 weeks after surgery. σ1R levels significantly decreased in astrocytes in both the hippocampal CA1 region and dentate gyrus. Oral administration of the specific σ1R agonist SA4503 (0.3-1.0mg/kg) significantly improved TAC-induced depression-like behaviors concomitant with rescued astrocytic σ1R expression in CA1 and the dentate gyrus. Plasma corticosterone levels significantly increased 6 weeks after TAC, and chronic treatment of mice with corticosterone for 3 weeks elicited depression-like behaviors concomitant with reduced astrocytic σ1R expression in hippocampus. Furthermore, the glucocorticoid receptor antagonist mifepristone antagonized depressive-like behaviors and ameliorated decreased hippocampal σ1R expression in TAC mice. We conclude that elevated corticosterone levels trigger hippocampal σ1R downregulation and that σ1R stimulation with SA4503 is an attractive therapy to improve not only cardiac dysfunction but depression-like behaviors associated with heart failure.

The role of medial prefrontal corticosterone and dopamine in the antidepressant-like effect of exercise.

Despite the well-documented beneficial effect of exercise on stress coping and depression treatment, its underlying neurobiological mechanism remains unclear. This is further complicated by a 'side effect' of exercise: it increases basal glucocorticoid (CORT), the stress hormone, which has been shown to be a mediator linking stress to depressive disorders. Here we show that three weeks of voluntary wheel running reduced rats' immobility in the forced swim test (FST), an antidepressant-like effect. Monitoring extracellular fluids in the medial prefrontal cortex PFC (mPFC) using microdialysis we found that, wheel running was associated with higher baseline CORT, but lower FST-responsive CORT. Further, wheel running resulted in a higher dopamine (DA) both at baseline and following FST. Interestingly, the antidepressant-like effect of wheel running was completely abolished by intra-mPFC pre-microinjection of a D2R (haloperidol) but not D1R (SCH23390) antagonist, at a dose that does not affect normal rats' performance in the FST. It suggests that exercise exerts antidepressant-like effect through upregulated DA and in a D2R dependent way in the mPFC. Importantly, the antidepressant-like effect of wheel running was also abolished by intra-mPFC pre-microinjection of a GR antagonist (RU486). Finally, intra-mPFC pre-microinjection of RU486 also downregulated the originally elevated basal and FST-responsive DA in the mPFC of exercise rats. These results suggest a causal pathway linking CORT, GR, DA, and D2R, to the antidepressant-like effect of exercise. In conclusion, exercise achieves antidepressant-like effect through the CORT-GR-DA-D2R pathway and that the increased basal CORT by exercise itself may be beneficial rather than detrimental.

Treadmill exercise ameliorates ischemia-induced brain edema while suppressing Na⁺/H⁺ exchanger 1 expression.

Exercise may be one of the most effective and sound therapies for stroke; however, the mechanisms underlying the curative effects remain unclear. In this study, the effects of forced treadmill exercise with electric shock on ischemic brain edema were investigated. Wistar rats were subjected to transient (90 min) middle cerebral artery occlusion (tMCAO). Eighty nine rats with substantially large ischemic lesions were evaluated using magnetic resonance imaging (MRI) and were randomly assigned to exercise and non-exercise groups. The rats were forced to run at 4-6m/s for 10 min/day on days 2, 3 and 4. Brain edema was measured on day 5 by MRI, histochemical staining of brain sections and tissue water content determination (n=7, each experiment). Motor function in some rats was examined on day 30 (n=6). Exercise reduced brain edema (P<0.05-0.001, varied by the methods) and ameliorated motor function (P<0.05). The anti-glucocorticoid mifepristone or the anti-mineralocorticoid spironolactone abolished these effects, but orally administered corticosterone mimicked the ameliorating effects of exercise. Exercise prevented the ischemia-induced expression of mRNA encoding aquaporin 4 (AQP4) and Na(+)/H(+) exchangers (NHEs) (n=5 or 7, P<0.01). Microglia and NG2 glia expressed NHE1 in the peri-ischemic region of rat brains and also in mixed glial cultures. Corticosterone at ~10nM reduced NHE1 and AQP4 expression in mixed glial and pure microglial cultures. Dexamethasone and aldosterone at 10nM did not significantly alter NHE1 and AQP4 expression. Exposure to a NHE inhibitor caused shrinkage of microglial cells. These results suggest that the stressful short-period and slow-paced treadmill exercise suppressed NHE1 and AQP4 expression resulting in the amelioration of brain edema at least partly via the moderate increase in plasma corticosterone levels.

Maternal postpartum corticosterone and fluoxetine differentially affect adult male and female offspring on anxiety-like behavior, stress reactivity, and hippocampal neurogenesis.

Postpartum depression (PPD) affects approximately 15% of mothers, disrupts maternal care, and can represent a form of early life adversity for the developing offspring. Intriguingly, male and female offspring are differentially vulnerable to the effects of PPD. Antidepressants, such as fluoxetine, are commonly prescribed for treating PPD. However, fluoxetine can reach offspring via breast milk, raising serious concerns regarding the long-term consequences of infant exposure to fluoxetine. The goal of this study was to examine the long-term effects of maternal postpartum corticosterone (CORT, a model of postpartum stress/depression) and concurrent maternal postpartum fluoxetine on behavioral, endocrine, and neural measures in adult male and female offspring. Female Sprague-Dawley dams were treated daily with either CORT or oil and fluoxetine or saline from postnatal days 2-23, and offspring were weaned and left undisturbed until adulthood. Here we show that maternal postpartum fluoxetine increased anxiety-like behavior and impaired hypothalamic-pituitary-adrenal (HPA) axis negative feedback in adult male, but not female, offspring. Furthermore, maternal postpartum fluoxetine increased the density of immature neurons (doublecortin-expressing) in the hippocampus of adult male offspring but decreased the density of immature neurons in adult female offspring. Maternal postpartum CORT blunted HPA axis negative feedback in males and tended to increase density of immature neurons in males but decreased it in females. These results indicate that maternal postpartum CORT and fluoxetine can have long-lasting effects on anxiety-like behavior, HPA axis negative feedback, and adult hippocampal neurogenesis and that adult male and female offspring are differentially affected by these maternal manipulations.