Developmental plasticity and acclimation both contribute to adaptive responses to alternating seasons of plenty and of stress in Bicyclus butterflies.

Plasticity is a crucial component of the life cycle of invertebrates that live as active adults throughout wet and dry seasons in the tropics. Such plasticity is seen in the numerous species of Bicyclus butterflies in Africa which exhibit seasonal polyphenism with sequential generations of adults with one or other of two alternative phenotypes. These differ not only in wing pattern but in many other traits. This divergence across a broad complex of traits is associated with survival and reproduction either in a wet season that is favourable in terms of resources, or mainly in a dry season that is more stressful. This phenomenon has led us to examine the bases of the developmental plasticity in a model species, B.anynana, and also the evolution of key adult life history traits, including starvation resistance and longevity. We now understand something about the processes that generate variation in the phenotype,and also about the ecological context of responses to environmental stress. The responses clearly involve a mix of developmental plasticity as cued by different environments in pre-adult development,and the acclimation of life history traits in adults to their prevailing environment.

Endoplasmic reticulum (ER) stress & diabetes.

The endoplasmic reticulum (ER) is a central organelle entrusted with lipid synthesis, protein folding and protein maturation. It is endowed with a quality control system that facilitates the recognition and targeting of aberrant proteins for degradation. When the capacity of this quality control system is exceeded, a stress response (ER stress) is switched on. Prolonged stress leads to apoptosis and may thus be an important factor in the pathogenesis of many diseases. A complex homeostatic signaling pathway, known as the unfolded protein response (UPR), has evolved to maintain a balance between the load of newly synthesized proteins and the capacity of the ER to aid in their maturation. Dysfunction of the UPR plays an important role in certain diseases, especially those involving tissues dedicated to extracellular protein synthesis. Diabetes is an example of such a disease, since pancreatic beta-cells depend on efficient UPR signaling to meet the demands for constantly varying levels of insulin synthesis. Recent studies have indicated that the importance of the UPR in diabetes is not restricted to the beta-cell but also to tissues of peripheral insulin resistance such as liver and adipose tissue. Better understanding of the basic mechanisms of ER stress and development of insulin resistance/type 2 diabetes is pivotal for the identification of newer molecular targets for therapeutic interventions.

comparison of myocardial perfusion gated SPECT studies obtained at rest and after stress

To perform a comparison between post-stress and rest gated single-photon emission computer tomography [SPECT] myocardial perfusion imaging [MPI] studies to assess post-stress stunning and the variables underlying this phenomenon. This was a prospective study of 318 consecutive adult patients undergoing stress and rest gated SPECT using a 2-day 99mTc-tetrofosmin protocol. Bruce protocol treadmill stress [n = 93] or i.v. dipyridamole pharmacologic stress [n = 225] were used as stressors. Ejection fractions [EF] and left ventricular [LV] end-diastolic [EDV] and end-systolic volumes [ESV] were calculated using the Cedars Sinai Quantitative Gated SPECT software. Perfusion defects were visually scored using a 20-segment model to obtain summed stress scores. Statistical analysis was performed by applying paired t test and multi-regression. Statistically significant [p < 0.05] paired differences between post-stress and rest EF and ESV and type of stressing were noted. Results: Analysis of patient groups based on the type of stress showed significantly low EF on post-stress studies for both treadmill and dipyridamole stressing and also significantly high ESV on post-stress studies for dipyridamole. Multi-regression analysis using differences in post-stress and rest EF, EDV and ESV as dependent and summed stress scores, type of stress, delay time, previous myocardial infarction and size of LV as independent variables showed statistically significant associations between high summed stress scores [>13] and size of post-stress LV for EDV and ESV differences. High volumes were noted on post-stress studies. The magnitudes of the observed differences were well within the reproducibility of LV volume calculations. Patients showing stunning had significant ischemia or a dilated LV. The stunning manifested as high EDV and ESV differences. The magnitude of the differences observed in EF and LV volumes were not clinically significant

Isoproterenol ameliorates workstress-induced rat skeletal muscle degeneration.

Beta-Agonists though have been widely studied for their protein anabolic effects in skeletal muscles, but the lipid status under work stress and agonist treatment have not been understood well in the skeletal muscles and heart of rat. In the present study, adult male Wistar rats were subjected to work overload stress and beta agonist isoproterenol treatment (2 mg kg(-1) day(-1) intraperitoneally) to examine, whether it attenuates work stress-induced changes or not. Simultaneously, beta2 antagonist butoxamine (2 mg kg(-1) day(-1) intraperitoneally) was administered to another isoproterenol-treated group. Work stress led to myofibrillar degeneration as well as rapid utilization of lipid to meet increased energy demands and for muscle repair, which was reflected through histochemical localization of lipids and biochemical estimation of cholesterol and triglycerides. Significantly decreased cholesterol levels in skeletal muscles and heart muscles were noticed. As expected, isoproterenol reversed the conditions by raising cholesterol and triglyceride levels significantly in the skeletal muscles and also by ameliorating the degenerative changes in muscle fibres as induced by work overload. However, severe accumulation of lipids in heart infers towards deleterious effects of isoproterenol on heart and thus remains a limiting factor for its immediate clinical application. Further research is needed to separate desirable effects of beta agonists on skeletal muscles from any undesirable effects on the heart, so as to optimize their therapeutic potential.

Progesterone restores stress induced inhibition of estrous behavior in rat.

Exposure to a stressor (mild electrical shocks to foot, five times per episode, at 1800, 1830, 1900 and 1930 hrs of proestrus) coinciding with period of pre-ovulatory progesterone secretion in rats abolished estrous behavior as shown by the absence of lordosis response and a significant increase in rejection quotient compared to controls. These rats did not show spermatozoa in the vaginal smear next day morning in contrast to their presence in controls. On the other hand, rats treated with progesterone (a single injection, 500 microg in 0.1 ml olive oil at 1800 hr of proestrus) prior to exposure to stressor showed normal estrous behavior, as shown by significantly lower rejection quotient than rats exposed to stress alone, lordosis quotient similar to controls and presence of spermatozoa in the vaginal smear next day. The results, albeit indirectly, to the best of our knowledge, first time indicate that stress induced impaired steroidogenesis leads to suppression of estrous behavior.

Correlation of serum cortisol levels and stress among medical doctors working in emergency departments

To assess and correlate serum cortisol levels and self-perceived work-related stress among medical doctors working in emergency departments in different tertiary care hospitals of Karachi. Cohort study. The study was conducted in Section of Chemical Pathology, Department of Pathology and Microbiology, AKUH, from December 2004 to August 2005. A total of 64 doctors participated from one private and two public tertiary care hospitals of Karachi. Thirtyfour doctors were from emergency departments and 30 from non-emergency departments. Serum cortisol levels were measured in the morning [between 8.00-8.30 am] and in the evening [between 8.00-8.30 pm]. Cortisol was measured by Florescence Polarization Immunoassay [FPIA] technique. Two questionnaires, modified mental Professional Stress Scale [PSS] and Aga Khan University Anxiety and Depression Scale [AKUADS] were used to assess stress levels. Emergency room physicians [ERP] were 1.2-year younger than non-emergency room physicians [NERP]. Mean evening cortisol of emergency physicians was 60.72nmol/L higher than non-emergency physicians. The difference between morning and evening cortisol was marginally significant [p = 0.051]. Morning diastolic blood pressure was 3mmHg higher in emergency physicians. Forty-one percent of emergency physicians and 20% of non-emergency physicians had AKUADS more than or equal to 20, the difference was borderline significant [p = 0.068]. Mean value of professional stress scale for emergency physicians was significantly higher than non-emergency physicians. Evening serum cortisol concentration was significantly associated with PSS [p = 0.011]. The sub-scales such as work-load [p = 0.007] and lack of resources were highly significant with evening cortisol [p = 0.005]. In this study, evening serum cortisol levels significantly correlated with work overload and lack of resources, however, there was marginally significant correlation between morning and evening serum cortisol difference. Study suggests that emergency physicians perceive more stress than non-emergency physicians. Work overload and lack of resources are major contributing factors for stress in these doctors

Neurohormonal changes in medical students during academic srtess

Academic stress is a good model of psychological stress in humans and is thus useful for studying psychoneurohormonal changes. The aim of the current study was to examine the effect of academic examination stress on activation of the hypothalamus-autonomic nervous system [HANS] and the hypothalamic-pituitary-adrenocortical [HPA] axis, through the measurements of changes in neuro-hormones during final exams as compared to the pre-exam baseline. Forty-eight first- and second-year female medical students participated. Plasma leptin, neuropeptide Y [NPY], nitrite, nitrate, andrenomedullin, cortisol and adrenocorticotropic hormone [ACTH] were measured at baseline and during final examinations. Plasma levels of cortisol, ACTH, NPY, adrenomedullin, nitrite and nitrate increased during times of academic stress as compared to baseline levels. However, only plasma leptin level was decreased during the academic stress as compared to baseline, probably through a negative feedback mechanism resulting from sympathetic stimulation. The results indicate that both the HANS and HPA are involved in this type of stress and both are activated at the same time. Academic stress induced significant neurohormonal changes. Leptin, NPY, nitrite, nitrate, adrenomedullin, cortisol and ACTH can be considered part of a complex mosaic model of the neuroendocrine system during academic stress

The Effect of Infant Massage on Weight Gain, Physiological and Behavioral Responses in Premature Infants / 간호학회지

PURPOSE: The purpose of this study was to evaluate the premature infants' responses to infant massage (tactile and kinesthetic stimulation). These responses measured by weight, physiological (vagal tone, heart rate, oxygen saturation) and behavioral responses (behavioral states, motor activities, and behavioral distress). METHODS: This study was conducted using an equivalent control pretest-posttest design. The sample was divided into two groups of 13 infants with gestational age less than 36 weeks at birth, birth weight less than 2000g, and no congenital anomalies. The experimental group received the massage intervention twice daily for 10 days. The data were collected for 10 minutes prior to and 10 minutes after the massage. RESULTS: The vagal tone was significantly higher after massage than before massage in the experimental group, while no change in the control group. The experimental group had significantly higher scores for awake state and motor activity than the control group. Significantly greater awake state, more fidgeting or crying, and increased motor activity were reported after massage than before massage. CONCLUSIONS: The results of this study showed that massage therapy might enhance optimal physiological responses and behavioral organization of premature infants. Nursing staff in the NICU can use massage to promote the infant's capability to respond positively to his environment and to provide developmental support for healthy premature infants.

Effect of orthostatic stress on systolic time intervals in rabbits.

Systolic time intervals (STI) are sensitive indices of myocardial function. The present study was conducted to evaluate the effect of orthostatic stress on STI before and after 70 degrees head up tilt (HUT) in rabbits. Electrocardiogram (ECG), phonocardiogram and carotid arterial pulse were recorded simultaneously on four channel polyrite (INCO). Within 1 second of tilt there was a significant rise (P<0.001) in electromechanical systole (QS2), left ventricular ejection time (LVET), pre-ejection period (PEP), and ratio of PEP/LVET (P<0.01), however, there was no change in heart rate and mean arterial blood pressure insignificantly. QT/QS2 ratio and ejection fraction (EF) were also elevated (P<0.05) on tilt. After 20 seconds of HUT, QS2 showed reduction (P < 0.001), LVET elevation (P < 0.001), PEP and ratio of PEP/LVET reduction (P < 0.001) from control level. QT/QS2 and EF declined gradually towards basal values. These changes in STI (raised LVET, reduced PEP and PEP/LVET ratio) and increased QT/SQ2 ratio and EF pointed towards rise in contractility of heart.

Modulation of stress induced by isometric handgrip test in hypertensive patients following yogic relaxation training.

13 essential hypertensive patients aged 41 to 60 years were given yoga training for 60 min daily, Monday through Saturday, for a total duration of 4 weeks. Blood pressure and heart rate (HR) were measured with non-invasive semi-automatic blood pressure monitor. Measurements were recorded before the training and at weekly intervals during the 4 week training period. Results of our study show a significant (P<0.001) reduction in resting HR and rate-pressure-product (RPP) after 2 weeks of yoga training. Systolic pressure (SP), diastolic pressure (DP) (P<0.001) and mean pressure (MP) (P<0.05) showed a significant reduction at 3 weeks of training period. After 4 weeks of training, there was further fall in SP, DP, pulse pressure (PP) (P<0.05), MP (P<0.001), HR and RPP. Isometric handgrip test before yoga training produced a significant rise in SP and MP and insignificant rise in DP, HR and RPP. After yoga training, there was a significant rise in all these parameters. Our results show that yoga training optimises the sympathetic response to stressful stimuli like isometric handgrip test and restores the autonomic regulatory reflex mechanisms in hypertensive patients.

Impact of chronic noise exposure on stress response, cardiovascular system and auditory system among marble and granite workers

Noise-induced hearing loss is a major health risk worldwide. Also, noise is one of the commonest physical stressors to which industrial workers are exposed. The objective of this study was to find out whether chronic exposure of workers to loud occupational noise during the daytime would cause changes in their cardiovascular system, stress hormone levels and their hearing thresholds. Thirty eight male marble and granite workers were interviewed, using questionnaires, as regards their medical and occupational history, use of hearing protection and they underwent clinical and laboratory examinations including measurement of blood pressure, ECG and pure-tone audiometry. We assessed noise-induced alterations in physiological stress by measuring serum and urinary levels of cortisol, catecholamines and the lipid profile. In the study areas, the noise levels ranged from 90 to 105 dBA. Results were analyzed and compared with the data of 20 normal persons matched in age, sex and socioeconomic status. Compared to the control group, the exposed workers showed statistically significant noise-induced hearing loss. Noise exposure produced physiological stress responses in workers in the form of significant increase in the serum and urinary cortisol levels after exposure to noise. Also, the exposed group displayed greater serum lipid responses and higher catecholamines levels than their controls. urthermore, blood pressure was significantly higher and ECG changes were more significant among the exposed than the control group. The present data suggest that chronic noise exposure might potentially lead to endocrine dysfunctions. Thus, we can say that workers exposed to loud occupational noise react to the stress and show, in addition to the NIHL, changes in the ECG and development of hypertension which may be attributed to the exposure to noise

Forced swimming stress induced alterations in ingestive behavior in rats.

The effects of forced swimming stress (15 minutes per day) on body weight, food intake, blood sugar, water intake, and urine output were studied in adult male Wistar rats on the first, seventh, fourteenth and 21st days in different subgroups. There was a significant initial decrease in the body weight up to 14 days followed by a regain in the body weight, which was sustained until 21 days. Though there was no change in the food intake initially for 7 days, after 14 days a significant increase in the food intake was observed. A significant hypoglycemia was observed throughout the entire period of stress. More significant fall in the blood sugar level was observed in the initial period of exposure of stress (1-7 days). There was a significant reduction in the water intake in the stressed animals. Urine output decreased significantly up to 7 days of stress, though it got marginally increased later. Thus, repeated stress may produce a reduction in body weight only initially, which is accompanied with an initial decrease in food and water intake also. The peak response to stress was seen after 7 days of stress exposure. There was a gradual recovery back to normal in the body weight, food intake, and water intake and urine output when stress period was prolonged to 14-21 days. This is suggestive of the adaptation of the organism to repeated exposure of similar kind of stress.

Effect of poly herbal formulation, EuMil, on chronic stress-induced homeostatic perturbations in rats.

EuMil, is a herbal formulation comprising the standardised extracts of Withania somnifera (L) Dunal, Ocimum sanctum L, Asparagus racemosus Willd and Emblica officinalis Gaertn., all of which are classified in Ayurveda as rasayanas to promote physical and mental health, improve defense mechanisms of the body and enhance longevity. These attributes are similar to the modern concept of adaptogenic agents, which are, known to afford protection to the human physiological system against diverse stressors. The present study was undertaken to investigate the adaptogenic and antistress activity of EuMil against chronic unpredictable, but mild, footshock stress-induced perturbations in behaviour (depression), glucose metabolism, suppressed male sexual behaviour, immunosuppression and cognitive dysfunction in CF strain albino rats. Panex ginseng (PG) was used for comparison. Gastric ulceration, plasma corticosterone levels, serum lipid, hepatic and renal functions were used as the stress indices. These effects were attenuated by EuMil (dose 100 mg/kg, p.o.) and PG (100 mg/kg. p.o.), administered once daily over a period of 14 days, the period of stress induction period. Further, chronic stress also induced glucose intolerance, suppressed male sexual behaviour, induced behavioural despair and cognitive dysfunction and immunosuppression. All these chronic stress-induced perturbations were attenuated, in a dose dependent manner by EuMil and PG. Thus, the results indicate that EuMil has significant adaptogenic and anti-stress, activity, qualitatively comparable to PG, against a variety of behavioural, biochemical and physiological perturbations, induced by unpredictable stress, which has been proposed to be a better indicator of clinical stress than acute stress. The likely contribution of the individual constituents of EuMil in the observed adaptogenic action of the polyherbal formulation, has been discussed.

Bile flow response to repetitive heat stress in rats.

BACKGROUND & OBJECTIVES: Heat stress produces loss of absorptive surface area of the small intestine, including the ileum which is the site of bile acid absorption. This may cause diarrhoea on account of the possible bile acid malabsorption. To explore this possibility, the effect of high ambient temperature exposure on bile flow was studied in the warm acclimated albino rats. METHODS: Following heat exposure at 38 +/- 0.5 degrees C for 4 h/day, for up to 5 consecutive days, bile flow in the rats was measured gravimetrically under pentobarbital-induced anaesthesia, at steady rectal temperature (37 +/- 0.7 degrees C), and flow characteristics and rate were studied. RESULTS: The bile flow increased with the rise in rectal temperature (Tre) in an anaesthetized animal but, the relationship between the two was not linear; the flow nearly ceased if rectal temperature exceeded 43 degrees-44 degrees C. At steady, near normal, rectal temperature, bile flow showed fluctuations and, repetitive heat exposure led to a significant increase in bile flow. INTERPRETATION & CONCLUSION: Exposure to high ambient temperature modulates liver secretory function to enhance bile flow rate and increase bile acid absorptive load on the small intestine, whose absorptive function is known to be adversely affected in heat stress.

Stress and hippocampus / 法医学杂志

This review summarizes the present advance of effects of stress on hippocampal structure and function and the role of hippocampus in feedback regulation of thalamic-pituitary-adrenocortical (HPA) axis during stress. It shows that stress can affect hippocampal structure and function, on the other hand, the hippocampus can also suppress the stress reaction through the feedback regulation of HPA axis, but chronic stress can attenuate this regulation, then significantly impair its structure and function.

Assessment of physiological stress in periparturient cows and neonatal calves.

Pregnancy is considered to be one of the physiological stressors. The stress hormone, cortisol is significantly involved in various events during periparturient period including initiation of parturition. The study was conducted to estimate the serum cortisol concentration in cows and the neonatal calves in order to correlate the effect of cortisol on certain haematological and biochemical parameters such as blood glucose level (BGL), total plasma protein (TPP), lymphocyte:neutrophil ratio and mitogen induced lymphocyte proliferative response. Blood samples were collected from six cows in four periods, namely., 3 days prior to parturition, on the day of parturition, and 7 days after parturition. Blood samples were also collected from neonatal calves in the period 0, 7 and 14 days of age. Calves above two months of age and non-pregnant dry cows were considered as the controls. The serum cortisol concentration in cows on the day of parturition was significantly higher (P < 0.01) than controls and the value in calves was also significantly higher (P < 0.01) at 0 day than their controls. On the day of parturition BGL level of the dam and calves were significantly higher (P < 0.01), whereas the proliferative response of lymphocytes to mitogen was significantly lower (P < 0.01) than controls. However TPP levels did not differ significantly. This confirmed that the dam at the time of parturition and neonatal calf before taking colostrum are under a high risk of infection because of the low profile of immune status. The lymphocyte:neutrophil ratio also justified the above suggestion.

Estres: enfoque psiconeuroendocrino / Stress: psychoneuroendocrine approach

En esta revisión se analiza el estrés como parte integral de la vida y del proceso general de adaptación; la fisiopatología de los componentes principales de la respuesta al estrés: el eje hipotalámico-hipófisis-suprarrenal o sistema de la hormona liberadora de corticotrofina y el eje simpático-adrenomedular o sistema autonómico del "locus ceruleus" y de la nor-adrenalina; la estrecha interrelación entre el sistema neuroendocrino y el sistema inmunológico; las interacciones pueden dar lugar a procesos de significación patológica en múltiples sistemas orgánicos que explican cómo factores psicológicos y sociales influyen en las enfermedades somáticas

Prevention of adrenocortical hyperactivity by dietary casein in rats exposed to forced swimming stress.

Adrenal weight, adrenal hydroxysteroid dehydrogenase activity and serum corticosterone level were significantly higher in rats fed with 5% casein diet after 7 days of swimming stress (45 min/day) as compared to their controls. All the parameters were similar to their control levels in rats receiving 20% casein diet and exposed to swimming stress. The results suggest that casein can play an important role in preventing adrenocortical hyperactivity in swimming stressed rats.