Morphological and Histopathological Changes in Kidney and Suprarenal Glands in Hanging and Sudden Death – An Autopsy Based Study

Aim of this study was to detect and quantify histological changes in kidneys after exposure to acute and chronic stress. Rats were divided into the groups consisting of 12 animals: control group—freely moving (unstressed); rats subjected to immobilization for 2 h; rats subjected to repeated 2 h immobilization for ten consecutive days; rats subjected to repeated 2 h immobilization for two consecutive days. Eight features of histopathological damage were scored on normal (0) to severe (4) scale. Changes occured in the kidneys during both, acute and chronic stress. The most common type of degeneration is ‘cloudy swelling’ in epithelial cells of proximal and distal tubules and interstitial edema. Chronic stress induces more prominent changes, which inflict more glomeruls than acute stress. Acute and repetitive stress induces mild or moderate histopathologic changes in kidneys. Copyright © 2010 John Wiley & Sons, Ltd.

The differential effects of acute vs. chronic stress and their combination on hippocampal parvalbumin and inducible heat shock protein 70 expression

Accumulation of continuous life stress (chronic stress) often causes gastric symptoms. The development of gastric symptoms may depend on how humans adapt to the stressful events in their daily lives. Although acute stress delays gastric emptying and alters upper gastrointestinal motility in rodents, the effects of chronic stress on gastric motility and its adaptation mechanism remains unclear. Central oxytocin has been shown to have antistress effects. We studied whether central oxytocin is involved in mediating the adaptation mechanism following chronic repeated stress. Mice were loaded with acute and chronic stress (repeated stress for five consecutive days), and solid gastric emptying and postprandial gastric motility were compared between acute and chronic repeated stress. Expression of oxytocin and CRF mRNA in the hypothalamus was studied following acute and chronic repeated stress. Delayed gastric emptying during acute stress (43.1 +/- 7.8%; n = 6, P < 0.05) was completely restored to normal levels (72.1 +/- 2.4%; n = 6) following chronic repeated stress. Impaired gastric motility induced by acute stress was also restored following chronic repeated stress. Intracerebroventricular injection of oxytocin (0.1 and 0.5 microg) restored the impaired gastric emptying and motility induced by acute stress. The restored gastric emptying and motility following chronic repeated stress were antagonized by intracerebroventricular injection of oxytocin antagonists. Oxytocin mRNA expression in the supraoptic nucleus (SON) and paraventricular nucleus (PVN) of the hypothalamus was significantly increased following chronic repeated stress. In contrast, increased CRF mRNA expression in the SON and PVN in response to acute stress was significantly reduced following chronic repeated stress. Our study suggests the novel finding that the upregulation of central oxytocin expression is involved in mediating the adaptation mechanism following chronic repeated stress in mice.

Introduction Various studies have linked suicidal behavior, stress, affective disorders, and dysregulation of the hypothalamic-pituitary-adrenal (HPA) axis resulting from chronic stress. Chronic stress has been shown to cause enlargement of the adrenal glands, altering their function and potentially leading to suicidal behaviors in individuals with depression. This study aimed to compare the histological changes in the adrenal glands of individuals who died by suicide with those who experienced sudden death. Suicide victims are exposed to chronic stress, while individuals with sudden deaths face acute stress related to the act of dying. Methods This analytical study, approved by the Institutional Ethics Committee (IEC), was conducted in the Department of Forensic Medicine and Toxicology at Gandhi Medical College, Bhopal. The study included 100 confirmed cases of suicide, irrespective of gender, aged 15-60 years, with notable autopsy findings, relevant history, no signs of decomposition, and varying survival periods (including immediate deaths within 24 hours). Additionally, 20 controls were selected, involving individuals who died suddenly from causes other than suicide within 24 hours of the incident. Informed consent was obtained using a prescribed proforma from relatives and the police. Histological examination slides of the adrenals were prepared and analyzed. Data were collected and statistically analyzed using GraphPad software and Epi Info 7. Results Capsular hemorrhage was observed in 98% of suicide cases and 40% of controls. Nodulation was present in 48% of suicidal cases and 20% of controls. Zonal extension of zona fasciculata was specific to chronic stress in suicidal cases. In 25% of suicidal cases, a prominent extension of the medulla was noted. Irregular thinning of zona glomerulosa with shrunken cells and increased nuclear density in 88% of cases were considered specific to chronic stress conditions and suicide, not observed in controls. Lipid depletion was observed in all suicidal cases, with diffuse depletion in 47% and focal depletion in 53% of cases. In contrast, 45% of those exposed to the acute stress of dying showed focal depletion, with none exhibiting diffuse depletion. Suicidal cases displayed dilated prominent sinusoids in all three zones and the adrenal medulla (98-99%), absent in controls. Adrenal hemorrhage and necrosis were specific to chronic stress conditions, with 7%, 8%, 32%, and 16% of cases showing hemorrhage in all three zones and adrenal medulla, respectively, and none in controls. Conclusion Histological changes observed in acute stress conditions included focal lipid depletion, capsular hemorrhage, nodular hyperplasia, and hemorrhage and necrosis with edema. However, the proportion and severity of these changes were lower than those observed in the suicidal group, suggesting that these findings may be considered non-specific for differentiating between acute and chronic stress.

Effects of acute and chronic restraint stress on nitroglycerin-induced hyperalgesia in rats

This study explored the relatively neglected role of chronic stress in major depression, examining the independent contributions of co-occurring chronic and acute stress to depression, whether chronic stress predicts acute life events, and whether the two types of stress interact such that greater chronic stress confers greater sensitivity-or resistance-to the depressive effects of acute stressors. From a sample of 816 community women, those who had a major depression onset in the past 9 months and those without major depressive episodes (MDE) onset and with no history of current or recent dysthymic disorder were compared on interview-based measures of antecedent acute and chronic stress. Chronic stress interviews rated objective stress in multiple everyday role domains, and acute stress was evaluated with contextual threat interviews. MDE onset was significantly associated with both chronic and acute stress; chronic stress was also associated with the occurrence of acute events, and there was a trend suggesting that increased acute stress is more strongly associated with depression in those with high versus low chronic stress. Results suggest the importance of including assessment of chronic stress in fully understanding the extent and mechanisms of stress-depression relationships.

Although psychological stress has long been known to alter cardiovascular function, there have been few studies on the effect of psychological stress on platelets, which play a pivotal role in cardiovascular disease. In the present study, we investigated the effects of acute and chronic psychological stress on the aggregation of platelets and platelet cytosolic free calcium concentration ([Ca2+]i). Mice were subjected to both transportation stress (exposure to novel environment, psychological stress) and restraint stress (psychological stress) for 2 h (acute stress) or 3 weeks (2 h/day) (chronic stress). In addition, adrenalectomized mice were subjected to similar chronic stress (both transportation and restraint stress for 3 weeks). The aggregation of platelets from mice and [Ca2+]i was determined by light transmission assay and fura-2 fluorescence assay, respectively. Although acute stress had no effect on agonist-induced platelet aggregation, chronic stress enhanced the ability of the platelet agonists thrombin and ADP to stimulate platelet aggregation. However, chronic stress failed to enhance agonist-induced increase in [Ca2+]i. Adrenalectomy blocked chronic stress-induced enhancement of platelet aggregation. These results suggest that chronic, but not acute, psychological stress enhances agonist-stimulated platelet aggregation independently of [Ca2+]i increase, and the enhancement may be mediated by stress hormones secreted from the adrenal glands.

The interaction of acute and chronic stress impairs model-based behavioral control

Immunoreactive beta-endorphin (IR-BE) levels in the plasma, anterior pituitary (AP), the neurointermediate lobe of the pituitary (NIL), and the hypothalamus were determined in castrated female rats and castrated female rats treated with estradiol benzoate (estrogen), after exposure to acute (once for 45 min) or chronic (45 min each day for 15 consecutive days) immobilization stress. Acute and chronic stress increased plasma levels of IR-BE to the same extent in castrated female rats and castrated female rats treated with estrogen. In castrated female rats, acute stress produced an increase in the concentration of IR-BE in the AP, which was attenuated by the administration of estrogen. Although IR-BE in the NIL was not influenced by acute stress in castrated animals, exposure to acute stress resulted in an elevation in IR-BE levels in the NIL of rats given estrogen. Chronic stress did not affect the concentration of IR-BE in the AP of castrated females or castrated females treated with estrogen. Chronic stress did, however, increase the concentration of IR-BE in the NIL of castrated animals. This affect of stress on IR-BE levels in the NIL was potentiated by estrogen administration. IR-BE levels in the hypothalamus were reduced by estrogen and were not affected by acute or chronic stress, regardless of the gonadal steroid environment. As determined by column chromatography, administration of estrogen, as well as subjection to chronic stress, promoted the processing of the proopiomelanocortin precursor to form beta-lipotropin rather than beta-endorphin in the AP. By these methods, the only immunoreactivity detected in the NIL and the hypothalamus was beta-endorphin. These data indicate that IR-BE levels in the plasma, the AP, and the NIL of female rats are affected by immobilization stress and that estrogen modulates the effects of acute immobilization stress on IR-BE levels in the AP and the NIL and the effects of chronic immobilization stress on the levels of IR-BE in the NIL.

Relatively high-latitude coral reefs could be potential “refuges” for corals under climate change. One of the most important aspects limiting their availability as refuges is low-temperature stress. However, the mechanisms underlying the response of coral holobionts to low-temperature stress is unclear. In this study, we aimed to explore the underlying mechanisms by recording the maximum quantum yields of photosystem II (Fv/Fm) and transcriptome responses of Porites lutea under acute (1–2 weeks) and chronic (6–12 weeks) low-temperature stress at 20°C and 14°C. The P. lutea samples were collected from a relatively high-latitude coral reef in the South China Sea (109°00′–109°15′E and 21°00′–21°10′ N). The study suggested that: (1) Under acute low-temperature stress, the Fv/Fm of Symbiodiniaceae dropped by 64%, which was significantly higher than the 49% observed under chronic stress. Low-temperature stress inhibited photosystem II(PSII) functioning, with greater inhibition under acute stress. (2) Downregulation of sugar metabolism-related genes under low-temperature stress implied that the decrease in energy was due to obstruction of PSII. (3) Under low-temperature stress, calcification-related genes were downregulated in coral hosts, possibly because of energy deprivation caused by inhibited photosynthesis, Symbiodiniaceae expulsion, and oxidative phosphorylation uncoupling in mitochondria. (4) Acute low-temperature stress induced the upregulation of genes related to the TNF signaling pathway and endoplasmic reticulum stress, promoting apoptosis and coral bleaching. However, these phenomena were not observed during chronic stress, suggesting acclimation to chronic low-temperature stress and a greater survival pressure of acute low-temperature stress on coral holobionts. In conclusion, low-temperature stress inhibits Symbiodiniaceae PSII functioning, reducing energy production and affecting calcification in coral holobionts. Acute low-temperature stress is more threatening to coral holobionts than chronic stress.

Accumulation of continuous life stress (chronic stress) often causes gastric symptoms. Although central oxytocin has antistress effects, the role of central oxytocin in stress-induced gastric dysmotility remains unknown. Solid gastric emptying was measured in rats receiving acute restraint stress, 5 consecutive days of repeated restraint stress (chronic homotypic stress), and 7 consecutive days of varying types of stress (chronic heterotypic stress). Oxytocin and oxytocin receptor antagonist were administered intracerebroventricularly (icv). Expression of corticotropin-releasing factor (CRF) mRNA and oxytocin mRNA in the paraventricular nucleus (PVN) of the hypothalamus was evaluated by real-time RT-PCR. The changes of oxytocinergic neurons in the PVN were evaluated by immunohistochemistry. Acute stress delayed gastric emptying, and the delayed gastric emptying was completely restored after 5 consecutive days of chronic homotypic stress. In contrast, delayed gastric emptying persisted following chronic heterotypic stress. The restored gastric emptying following chronic homotypic stress was antagonized by icv injection of an oxytocin antagonist. Icv injection of oxytocin restored delayed gastric emptying induced by chronic heterotypic stress. CRF mRNA expression, which was significantly increased in response to acute stress and chronic heterotypic stress, returned to the basal levels following chronic homotypic stress. In contrast, oxytocin mRNA expression was significantly increased following chronic homotypic stress. The number of oxytocin-immunoreactive cells was increased following chronic homotypic stress at the magnocellular part of the PVN. Icv injection of oxytocin reduced CRF mRNA expression induced by acute stress and chronic heterotypic stress. It is suggested that the adaptation mechanism to chronic stress may involve the upregulation of oxytocin expression in the hypothalamus, which in turn attenuates CRF expression.

Chronic and acute stress differentially affect behavior as well as the structural integrity of the hippocampus, a key brain region involved in cognition and memory. However, it remains unclear if and how the facilitatory effects of acute stress on hippocampal information coding are disrupted as the stress becomes chronic. To examine this, we compared the impact of acute and chronic stress on neural activity in the CA1 subregion of male mice subjected to a chronic immobilization stress (CIS) paradigm. We observed that following first exposure to stress (acute stress), the spatial information encoded in the hippocampus sharpened, and the neurons became increasingly tuned to the underlying theta oscillations in the local field potential (LFP). However, following repeated exposure to the same stress (chronic stress), spatial tuning was poorer and the power of both the slow-gamma (30–50 Hz) and fast-gamma (55–90 Hz) oscillations, which correlate with excitatory inputs into the region, decreased. These results support the idea that acute and chronic stress differentially affect neural computations carried out by hippocampal circuits and suggest that acute stress may improve cognitive processing.

The effects of immobilization stress on beta-endorphin levels are modulated by testosterone

Evidence suggests that when presented with novel acute stress, animals previously exposed to chronic homotypic or heterotypic stressors exhibit normal or enhanced hypothalamic-pituitary-adrenal (HPA) response compared with animals exposed solely to that acute stressor. The molecular mechanisms involved in this effect remain unknown. The extracellular signal-regulated kinase (ERK) is one of the key pathways regulated in the hippocampus in both acute and chronic stress. The aim of this study was to examine the interaction of prior chronic stress, using the chronic variable stress model (CVS), with exposure to a novel acute stressor (2,5-dihydro-2,4,5-trimethyl thiazoline; TMT) on ERK activation, expression of the downstream protein BCL-2, and the glucocorticoid receptor co-chaperone BAG-1 in control and chronically stressed male rats. TMT exposure after chronic stress resulted in a significant interaction of chronic and acute stress in all 3 hippocampus subregions on ERK activation and BCL-2 expression. Significantly, acute stress increased ERK activation, BCL-2 and BAG-1 protein expression in the dentate gyrus (DG) of CVS-treated rats compared with control, CVS-treated alone, and TMT-only animals. Furthermore, CVS significantly increased ERK activation in medial prefrontal cortex, but acute stress had no significant effect. Inhibition of corticosterone synthesis with metyrapone had no significant effect on ERK activation in the hippocampus; therefore, glucocorticoids alone do not mediate the molecular effects. Finally, because post-translational modifications of histones are believed to play an important role in the stress response, we examined changes in histone acetylation. We found that, in general, chronic stress decreased K12H4 acetylation, whereas acute stress increased acetylation. These results indicate a molecular mechanism by which chronic stress-induced HPA axis plasticity can lead to neurochemical alterations in the hippocampus that influence reactivity to subsequent stress exposure. This may represent an important site of dysfunction that contributes to stress-induced pathology such as depression, anxiety disorders, and posttraumatic stress disorder.

The impact of nutritional and environmental stressors on the immune response, oxidative stress and energy use of rainbow trout (Oncorhynchus mykiss).