Glucocorticoids regulate adipose tissue protein concentration in a depot- and sex-specific manner.

Preclinical and clinical findings indicate that glucocorticoids (GC) induce lipid accumulation in visceral depots, while inhibiting lipid stores from subcutaneous depots. Whereas some suggest that this is due to adipose depot specific concentration of glucocorticoid receptors (GR) or 11beta-hydroxysteroid dehydrogenase 1 (11ß-HSD1), others demonstrate these events emerge from increases in interleukin-1 beta (IL-1ß) from macrophages within distinct depots. Regardless of the mechanisms, most of these studies occur in males and thus lack evaluation of sex differences. Here, we examined the impact of 2-week corticosterone (CORT) (3 mg/kg/day) or saline treatment on GR, 11ß-HSD1 and IL-1ß protein concentration in intra-abdominal (epididymal/parametrial, and visceral) and subcutaneous (inguinal) depots in male and female Sprague Dawley rats. The objective was to examine if factors that regulate GC-induced adipose depot metabolism and distribution, differ between males and females. CORT inhibited, but did not decrease, body weight gain in both sexes. 11ß-HSD1 was similar between the sexes in all adipose depots. CORT increased IL-1ß in both sexes only in gonadal adipose tissue. Overall, males had greater GR protein concentration in all adipose depots, whereas females had more IL-1ß in intra-abdominal adipose depots. Given the male-biased increase in intra-abdominal GR protein concentration, the data suggest that males may be more prone to CORT-induced increases in visceral obesity, which may have implications for increased risk for metabolic diseases. Overall, the data suggest that the effects of GC signaling in adipose tissue are multifaceted, dependent on sex, and the inherent adipocyte characteristics.Lay summaryResearch supports that glucocorticoids (GC) induce visceral adipose tissue accumulation, however few studies have examined if these GC-mediated outcomes are similar between males and females. This study investigates if female rats differentially respond to corticosterone treatment. Results indicate that male rats may have an increased susceptibility to CORT-induced accumulation of visceral adipose tissue compared with females, which may have implication for sex-specific risk for metabolic diseases.

Effects of combined glucocorticoid/mineralocorticoid receptor modulation (CORT118335) on energy balance, adiposity, and lipid metabolism in male rats.

Psychological stress and excess glucocorticoids are associated with metabolic and cardiovascular diseases. Glucocorticoids act primarily through mineralocorticoid (MR) and glucocorticoid receptors (GR), and compounds modulating these receptors show promise in mitigating metabolic and cardiovascular-related phenotypes. CORT118335 (GR/MR modulator) prevents high-fat diet-induced weight gain and adiposity in mice, but the ability of this compound to reverse obesity-related symptoms is unknown. Adult male rats were subcutaneously administered CORT118335 (3, 10, or 30 mg/kg) or vehicle once daily. A 5-day treatment with CORT118335 at 30 mg/kg induced weight loss in rats fed a chow diet by decreasing food intake. However, lower doses of the compound attenuated body weight gain primarily because of decreased calorific efficiency, as there were no significant differences in food intake compared with vehicle. Notably, the body weight effects of CORT118335 persisted during a 2-wk treatment hiatus, suggesting prolonged effects of the compound. To our knowledge, we are the first to demonstrate a sustained effect of combined GR/MR modulation on body weight gain. These findings suggest that CORT118335 may have long-lasting effects, likely due to GR/MR-induced transcriptional changes. Prolonged (18 days) treatment of CORT118335 (10 mg/kg) reversed body weight gain and adiposity in animals fed a high-fat diet for 13 wk. Surprisingly, this occurred despite a worsening of the lipid profile and glucose homeostasis as well as a disrupted diurnal corticosterone rhythm, suggesting GR agonistic effects in the periphery. We conclude that species and tissue-specific targeting may result in promising leads for exploiting the metabolically beneficial aspects of GR/MR modulation.

Sex differences in DEK expression in the anterior cingulate cortex and its association with dementia severity in schizophrenia.

DEK is a chromatin-remodeling phosphoprotein found in most human tissues, but its expression and function in the human brain is largely unknown. DEK depletion in vitro induces cellular and molecular anomalies associated with cognitive impairment, including down-regulation of the canonical Wnt/ß-catenin signaling pathway. ToppGene analyses link DEK loss to genes associated with various dementias and age-related cognitive decline. To examine the role of DEK in cognitive impairment in severe mental illness, DEK protein expression was assayed by immunoblot in the anterior cingulate cortex (ACC) of subjects with schizophrenia. Cognitive impairment is a core feature of schizophrenia and cognitive function in subjects was assessed antemortem using the clinical dementia rating (CDR) scale. DEK protein expression was not significantly altered in schizophrenia (n = 20) compared to control subjects (n = 20). Further analysis revealed significant reduction in DEK protein expression in women with schizophrenia, and a significant increase in expression in men with schizophrenia, relative to their same-sex controls. DEK protein expression levels were inversely correlated with dementia severity in women. Conversely, in men, DEK protein expression and dementia severity were positively correlated. Notably, there was no sex difference in DEK protein expression in the control group, suggesting that this sex difference is specific to schizophrenia and not due to inherent differences in DEK expression between males and females. These results suggest a novel, sex-specific role for DEK in cognitive performance and highlight a putative sex-specific link between central nervous system DEK protein expression and a neuropsychiatric disease that is commonly associated with cognitive impairment.

Differential effects of imipramine and CORT118335 (Glucocorticoid receptor modulator/mineralocorticoid receptor antagonist) on brain-endocrine stress responses and depression-like behavior in female rats.

Depression is commonly associated with hypothalamic-pituitary adrenal (HPA) axis dysfunction that primarily manifests as aberrant glucocorticoid secretion. Glucocorticoids act on Type I mineralocorticoid (MR) and Type II glucocorticoid receptors (GR) to modulate mood and endocrine responses. Successful antidepressant treatment normalizes HPA axis function, in part due to modulatory effects on MR and GR in cortico-limbic structures. Although women are twice as likely to suffer from depression, little is known about how antidepressants modulate brain, endocrine, and behavioral stress responses in females. Here, we assessed the impact of CORT118335 (GR modulator/MR antagonist) and imipramine (tricyclic antidepressant) on neuroendocrine and behavioral responses to restraint or forced swim stress (FST) in female rats (n=10-12/group). Increased immobility CORT118335 in the FST is purported to reflect passive coping or depression-like behavior. CORT118335 dampened adrenocorticotropic hormone (ACTH) and corticosterone responses to the FST, but did not affect immobility. Imipramine suppressed ACTH, but had minimal effects on corticosterone responses to FST. Despite these marginal effects, imipramine decreased immobility, suggesting antidepressant efficacy. In an effort to link brain-endocrine responses with behavior, c-Fos was assessed in HPA axis and mood modulatory regions in response to the FST. CORT118335 upregulated c-Fos expression in the paraventricular nucleus of the hypothalamus. Imipramine decreased c-Fos in the basolateral amygdala and hippocampus (CA1 and CA3), but increased c-Fos in the central amygdala. These data suggest the antidepressant-like (e.g., active coping) properties of imipramine may be due to widespread effects on cortico-limbic circuits that regulate emotional and cognitive processes.

Estrogen signaling in the medial amygdala decreases emotional stress responses and obesity in ovariectomized rats.

Declining estradiol (E2), as occurs during menopause, increases risk for obesity and psychopathology (i.e., depression, anxiety). E2 modulates mood and energy homeostasis via binding to estrogen receptors (ER) in the brain. The often comorbid and bidirectional relationship between mood and metabolic disorders suggests shared hormonal and/or brain networks. The medial amygdala (MeA) is abundant in ERs and regulates mood, endocrine, and metabolic stress responses; therefore we tested the hypothesis that E2 in the MeA mitigates emotional and metabolic dysfunction in a rodent model of surgical menopause. Adult female rats were ovariectomized (OVX) and received bilateral implants of E2 or cholesterol micropellets aimed at the MeA. E2-MeA decreased anxiety-like (center entries, center time) and depression-like (immobility) behaviors in the open field and forced swim tests (FST), respectively in ovariectomized rats. E2-MeA also prevented hyperphagia, body weight gain, increased visceral adiposity, and glucose intolerance in ovariectomized rats. E2-MeA decreased caloric efficiency, suggestive of increased energy expenditure. E2-MeA also modulated c-Fos neural activity in amygdalar (central and medial) and hypothalamic (paraventricular and arcuate) brain regions that regulate mood and energy homeostasis in response to the FST, a physically demanding task. Given the shared neural circuitry between mood and body weight regulation, c-Fos expression in discrete brain regions in response to the FST may be due to the psychologically stressful and/or metabolic demands of the task. Together, these findings suggest that the MeA is a critical node for mediating estrogenic effects on mood and energy homeostasis.

A mixed glucocorticoid/mineralocorticoid receptor modulator dampens endocrine and hippocampal stress responsivity in male rats.

Aberrant glucocorticoid secretion is implicated in the pathophysiology of stress-related disorders (i.e., depression, anxiety). Glucocorticoids exert biological effects via mineralocorticoid (MR) and glucocorticoid (GR) receptors. Previous data from our laboratory indicate that GR antagonism/modulation (i.e., mifepristone, CORT 108297) regulate endocrine, behavioral, and central stress responses. Because of the dynamic interplay between MR and GR on HPA axis regulation and emotionality, compounds targeting both receptors are of interest for stress-related pathology. We investigated the effects of CORT 118335 (a dual selective GR modulator/MR antagonist) on endocrine, behavioral, and central (c-Fos) stress responses in male rats. Rats were treated for five days with CORT 118335, imipramine (positive control), or vehicle and exposed to restraint or forced swim stress (FST). CORT 118335 dampened corticosterone responses to both stressors, without a concomitant antidepressant-like effect in the FST. Imipramine decreased corticosterone responses to restraint stress; however, the antidepressant-like effect of imipramine in the FST was independent of circulating glucocorticoids. These findings indicate dissociation between endocrine and behavioral stress responses in the FST. CORT 118335 decreased c-Fos expression only in the CA1 division of the hippocampus. Imipramine decreased c-Fos expression in the basolateral amygdala and CA1 and CA3 divisions of the hippocampus. Overall, the data indicate differential effects of CORT 118335 and imipramine on stress-induced neuronal activity in various brain regions. The data also highlight a complex relationship between neuronal activation in stress and mood regulatory brain regions and the ensuing impact on endocrine and behavioral stress responses.

Apolipoprotein AIV requires cholecystokinin and vagal nerves to suppress food intake.

Apolipoprotein AIV (apo AIV) and cholecystokinin (CCK) are gastrointestinal satiation signals that are stimulated by fat consumption. Previous studies have demonstrated that peripheral apo AIV cannot cross the blood-brain barrier. In the present study, we hypothesized that peripheral apo AIV uses a CCK-dependent system and intact vagal nerves to relay its satiation signal to the hindbrain. To test this hypothesis, CCK-knockout (CCK-KO) mice and Long-Evan rats that had undergone subdiaphragmatic vagal deafferentation (SDA) were used. Intraperitoneal administration of apo AIV at 100 or 200 µg/kg suppressed food intake of wild-type (WT) mice at 30, 60, and 90 min. In contrast, the same dose did not reduce food intake in the CCK-KO mice. Blockade of the CCK 1 receptor by lorglumide, a CCK 1 receptor antagonist, attenuated apo AIV-induced satiation. Apo AIV at 100 µg/kg reduced food intake in SHAM rats but not in SDA rats. Furthermore, apo AIV elicited an increase in c-Fos-positive cells in the nucleus of the solitary tract (NTS), area postrema, dorsal motor nucleus of the vagus, and adjacent areas of WT mice but elicited only an attenuated increase in these same regions in CCK-KO mice. Apo AIV-induced c-Fos positive cells in the NTS and area postrema of WT mice were reduced by lorglumide. Lastly, apo AIV increased c-Fos positive cells in the NTS of SHAM rats but not in SDA rats. These observations imply that peripheral apo AIV requires an intact CCK system and vagal afferents to activate neurons in the hindbrain to reduce food intake.

Apolipoprotein A-IV regulates chylomicron metabolism-mechanism and function.

Dietary fat is an important mediator of atherosclerosis and obesity. Despite its importance in mediating metabolic disease, there is still much unknown about dietary fat absorption in the intestine and especially the detailed biological roles of intestinal apolipoproteins involved in that process. We were specifically interested in determining the physiological role of the intestinal apolipoprotein A-IV (A-IV) using A-IV knockout (KO) mice. A-IV is stimulated by fat absorption in the intestine and is secreted on nascent chylomicrons into intestinal lymph. We found that A-IV KO mice had reduced plasma triglyceride (TG) and cholesterol levels and that this hypolipidemia persisted on a high-fat diet. A-IV KO did not cause abnormal intestinal lipid absorption, food intake, or adiposity. Additionally, A-IV KO did not cause abnormal liver TG and cholesterol metabolism, as assessed by measuring hepatic lipid content, lipogenic and cholesterol synthetic gene expression, and in vivo VLDL secretion. Instead, A-IV KO resulted in the secretion of larger chylomicrons from the intestine into the lymph, and those chylomicrons were cleared from the plasma more slowly than wild-type chylomicrons. These data suggest that A-IV has a previously unknown role in mediating the metabolism of chylomicrons, and therefore may be important in regulating plasma lipid metabolism.