Blood Corticosterone Concentrations Research Articles

Levels of Corticosterone and Glucose in Blood of Rats under Conditions of Chronic Unpredictable Stress of Different Duration

INTRODUCTION: Mammals are almost constantly exposed to a variety of stressors. The changes in the concentration of corticosterone and the level of glucose in blood of animals under such conditions seems relevant for understanding the influence of repeated stress effects on endocrine and metabolic processes. AIM: To study the concentrations of corticosterone and glucose in blood of rats in different time periods of prolonged low-intensity unpredictable stress. MATERIALS AND METHODS: Experiments were carried out on 42 male Wistar rats. Individuals of the experimental groups were subjected to 7-day cycles of alternating stressors using a modified model of chronic unpredictable mild stress with presentation of different stressors. The concentration of corticosterone and glucose in blood was determined at 1, 2, 3 and 4 weeks of observation. RESULTS: A pronounced decrease in corticosterone levels was found in rats at 1 week of stress exposure, followed by a slow recovery by the end of 4th week. Blood glucose level increased at 2 weeks of exposure. CONCLUSION: The data obtained illustrate the specificity of changes in the levels of glucose and corticosterone in the blood of mammals in different time periods of chronic stress. These changes characterize the dysregulation of the integrative physiological systems in relatively early periods of chronic stress with the subsequent development of adaptation in the later stages of repeated stress exposures.

Comparison of Novel and Traditional Bleeding Techniques in Neonatal and Juvenile Mice.

Blood collection is frequently used for neonatal and juvenile mice in toxicology, developmental, and immunology studies and is often a terminal procedure. However, the use of nonterminal blood collection techniques, including the submandibular and the submental collection techniques described for adult mice, may offer opportunities to reduce animal numbers and refine current methods. The use of the submental technique has not been described for neonatal or juvenile mice. In this study, we compared the submental and submandibular blood collection techniques to determine their suitability for use in neonatal and juvenile mice. Male and female CD1 mice, ages 7, 14, 21, and 28 d, were randomized by sex into submental (n = 16), submandibular (n = 16), or control (n = 8) groups. Each mouse was weighed, bled per its assigned group (or only restrained in the case of control mice), and then decapitated without anesthesia for terminal blood collection. Blood collection volume and corticosterone concentrations were measured. The 2 methods showed significant differences in the volume of blood collected at ages 14 and 28, with the submandibular technique yielding significantly higher volumes. No significant differences were detected in corticosterone levels between the 2 techniques based on age or sex. A subset of mice (n = 8, 2 per age group) were bled via submental or submandibular technique and were evaluated 48 h later for gross and histopathologic evidence of trauma. Seven of the 8 mice showed expected inflammation and healing at the collection sites, with 4 mice having embedded strands of fur in the tissue. These data indicate that the submental blood collection is a viable method for nonterminal blood collection method in neonatal and juvenile mice, especially when smaller amounts of blood are needed.

Circadian Corticosterone Profile in Laying Hens (Gallus gallus domesticus).

Measurement of blood corticosterone concentrations has been established as an indicator for assessment of acute distress. Therefore, knowledge on physiological fluctuations is required, but previous studies allow little conclusion on daily fluctuations in domestic chickens (Gallus gallus domesticus). To verify the presence of a circadian corticosterone rhythm in socialized chickens, blood samples were taken at four-hour intervals from 12 laying hens kept in groups of four over three days, each. Prior to experiments, hens were adapted to repeated handling for stress reduction. Corticosterone concentration was determined using radioimmunoassay. Blood sampling time and duration were recorded, and audio and video recordings were analyzed to assess the impact of behavior on corticosterone concentrations. Despite individual fluctuations, most hens showed a circadian course with two peaks per day. Statistics revealed a significant peak during the day (between 12:00 p.m. and 04:00 p.m.) and a tendency for a second peak at night (12:00 a.m.). The daily corticosterone peak was not explained by daytime social stress and needs to be seen as an endophenotype. The role of nightly corticosterone production has to be investigated in further studies. There might be a relation between corticosterone and reproduction since the only hen not showing peaks was not laying eggs.

ВЛИЯНИЕ ЭКСПЕРИМЕНТАЛЬНОЙ ДЕПРЕССИИ НА ФУНКЦИОНАЛЬНОЕ СОСТОЯНИЕ ГИПОТАЛАМО-ГИПОФИЗАРНО-НАДПОЧЕЧНИКОВОЙ СИСТЕМЫ

Objective: To study the effect of modelled depression not associated with stress on the hypothalamic-pituitary-adrenal system (HPAS) in mice. Methods: The experiment was conducted on the twenty-four C57BL/6 mice weighing 20-25 g, divided into two groups: an experimental one, involving animals with reserpine-induced depression, and a control one, the animals of which were administered normal saline instead of reserpine solution. At the end of the experiment, behavioral tests were performed (open field, sucrose preference, forced swimming), and the corticosterone concentration in blood was measured using ELISA. Image analysis of histological changes in the adrenal gland and thymus was performed. All results were statistically processed using SPSS 27.0.1 software, with p<0.05 indicating the significance of differences. Results: Animals of the experimental group showed a significantly higher level of corticosterone in the blood (p<0.01), significant changes in behavior in the open field test (distance traveled, rearing, frequency of urination and defecation, p<0.01), reduced sucrose preference (p<0.01) and shortened duration of the active phase in the forced swimming test (p<0.01) than the animals of the control group. Besides, in the mice of the experimental group, a significant increase in the volume density of the zona fasciculata of the adrenal cortex was found (p<0.05), as well as the area of its spongiocytes and their nuclei (p<0.05). In the thymus of the experimental animals, a significant decrease in the cortex-medulla ratio was noted (p<0.05); and an increase in the volume density of tingible body macrophages (p<0.05) compared to the control group of mice. Conclusion: Modelled depression, not associated with stress, the depth of which was assessed by behavioral tests, caused activation of the HPAS, manifested by increased corticosterone levels, hyperplasia of the zona fasciculata of the adrenal cortex, hypertrophy of its spongiocytes and their nuclei, as well as changes in the thymus, indicating associated immunosuppression. Thus, the study showed that, along with the well-known phenomenon of the development of depression against the background of chronic stress-associated activation of HPAS, there is an inverse mechanism leading to activation of the HPAS during the development of depression not associated with stress, which must be taken into account when developing the new strategies of treating depression. Keywords: Depression, hypothalamic-pituitary-adrenal system, corticosterone, immune system, mice.

Geraniol attenuates behavioral and neurochemical impairments by inhibitions of HPA-axis and oxido-inflammatory perturbations in mice exposed to post-traumatic stress disorder

Geraniol is an acyclic isoprenoid monoterpenoid analogue that has been shown to elicit neuroprotective functions, primarily through its ability to stimulate antioxidant and anti-inflammatory systems. An increase in inflammatory cytokines and oxidative stress exacerbate activation hypothalamic-pituitary-adrenal axis (HPA), leading to neurochemical dysfunction, which has important roles in the pathogenesis of post-traumatic disorder (PTSD), a mental health disorder characterized of post-trauma-induced intense fear. The aim of this study was to evaluate the anti-PTSD-like effects and underlying mechanisms of geraniol against single-prolonged-stress (SPS)-induced PTSD in mice. Following concomitant exposure to SPS (triple-paradigm traumatic events) and isolation for 7 days, mice (n = 9) were treated with geraniol (50 and 100 mg/kg, p.o.) or fluoxetine (10 mg/kg, p.o.) from days 8–21. Mice were assessed for behavioral changes. Neurochemical changes, inflammatory, oxido-nitrergic markers, adrenal weight, serum glucose and corticosterone concentrations were assayed. Geraniol inhibits SPS-induced anxiety- and depressive-like features as well as behavioral despair in the depression paradigms. SPS-induced locomotor and memory impairments were also abated by geraniol treatment similarly to fluoxetine. SPS-induced adrenal hypertrophy and increased blood glucose and corticosterone concentrations, were attenuated by the geraniol treatment. Elevated levels of TNF-α and IL-6, and malondialdehyde, nitrite, acetylcholinesterase enzyme were reduced by geraniol. Geraniol also increased glutathione, superoxide-dismutase, and catalase levels as well as dopamine, serotonin concentrations and GABAergic glutamic acid decarboxylase enzyme activity in the striatum, prefrontal cortex and hippocampus in the PTSD-mice relative to SPS control. In conclusion, geraniol attenuates behavioral impairments and neurochemical dysregulations by inhibitions of HPA-axis and oxido-inflammatory perturbations in mice exposed to PTSD.

Social confrontation stress decreases hepatic fibroblast growth factor-21 expression in aged mice

We previously showed that social stress exposure in mature adult mice increased blood corticosterone concentrations at 2 days, disrupted hepatic lipid metabolism-related pathway at 30 days, and increased the risk of overweight with hepatic hypertrophy at 90 days. To further investigate the effects of aging on the physiological responses to social stress, we conducted a study using male BALB/c mice at the ages of 2 months (mature age), 14 months (middle age) and 26 months (old age), and exposed them to confrontation stress for 2 or 7 days. Blood corticosterone concentrations were increased at 2 days of stress, and then returned to baseline concentrations. This change was observed only at 2 months of age. We further examined the effect of aging on hepatic gene expression of fibroblast growth factor-21 (Fgf21) and found that its expression was significantly decreased after 7 days of stress at 14 months of age and after 2 days of stress at 26 months of age, indicating these decreasing effects became more pronounced with age. In conclusion, our study suggests that hepatic Fgf21 expression decrease under exposure to confrontation stress at middle or more age, indicating that stress response on Fgf21 related pathway might be more pronounced with age when exposed to stress.

Getting a handle on rat familiarization: The impact of handling protocols on classic tests of stress in Rattus norvegicus.

Experimenter familiarization with laboratory rodents through handling prior to experimentation is an important practice in neurobehavioral research and is implicated in stress, study variability, and replicability. Unfortunately, different handling protocols have not been thoroughly examined. Determining optimal experimenter familiarization protocols is expected to reduce animal stress and thus improve welfare and data consistency. The impact of different handling protocols was determined through behavioral assessments (i.e. elevated plus maze, light/dark box, open field) as well as via analysis of fecal boli counts, ultrasonic vocalizations, and blood corticosterone. Male and female Sprague Dawley rats were distributed among three groups: never handled, picked-up, and handled for 5 min once daily over five days. Handled and picked-up rats spent more time in open arms and less time in closed arms of the elevated plus maze and more time in the center and less time at the perimeter of the open field compared to rats that were never handled, indicating that handled and picked-up rats were less anxious than those that were never handled. Male rats consistently defecated more frequently throughout the handling process and throughout behavioral testing, whereas females showed greater concentrations of blood corticosterone. Female rats were found to emit more 50-kHz calls and fewer 22-kHz calls compared to males. The results observed suggest that picking animals up may suffice as a handling method compared to time-intensive handling procedures, and that there are significant sex differences in response to handling.

The combination of chronic stress and smoke exacerbated depression-like changes and lung cancer factor expression in A/J mice: Involve inflammation and BDNF dysfunction.

Depression is positively correlated with the high incidence and low survival rate of cancers, while more cancer patients suffer depression. However, the interaction between depression and cancer, and possible underline mechanisms are unclear. Chronic unpredictable mild stress (CUMS) was used to induce depression, and smoke to induce lung cancer in lung cancer vulnerable AJ mice. After 8 weeks, sucrose preference and forced swimming behaviors were tested. Blood corticosterone concentration, and levels of cytokines, lung cancer-related factors, brain-derived neurotrophic factor (BDNF) and apoptosis-related factors in the lung, amygdala and hippocampus were measured. Compared to control group, CUMS or smoke decreased sucrose consumption and increased immobility time, which were deteriorated by stress+smoke. CUMS, smoke or both combination decreased mononuclear viability and lung TNF-α concentration, increased serum corticosterone and lung interleukin (IL)-1, IL-2, IL-6, IL-8, IL-10, IL-12 and HSP-90α concentrations. Furthermore, stress+smoke caused more increase in corticosterone and IL-10, but decreased TNF-α. In parallel, in the lung, Bcl-2/Bax and lung cancer-related factors CDK1, CDC20, P38α etc were significantly increased in stress+smoke group. Moreover, CUMS decreased BDNF, while CUMS or smoke increased TrkB and P75 concentrations, which were exacerbated by stress+smoke. In the amygdala, except for CUMS largely increased Bax/Bcl-2 and decreased TrkB, each single factor decreased BDNF and IL-10, but increased P75, IL-1β, IL-12, TNF-α concentrations. Changes in Bax/Bcl-2, IL-10 and TNF-α were further aggravated by the combination. In the hippocampus, except for CUMS largely increased P75 concentration, each single factor significantly increased Bax/Bcl-2 ratio, IL-1β and TNF-α, but decreased BDNF, TrkB and IL-10 concentrations. Changes in Bax, Bax/Bcl-2, IL-10 and TNF-α were further aggravated by the combination. These results suggest that a synergy between CUMS and smoke exposure could promote the development of depression and lung cancer, through CUMS increased the risk of cancer occurrence, and conversely lung cancer inducer smoke exposure deteriorated depressive symptoms.

Fatty acid amide hydrolase inhibition and N-arachidonoylethanolamine modulation by isoflavonoids: A novel target for upcoming antidepressants.

Modulation of the endocannabinoid system (ECS) is a novel putative target for therapeutic intervention in depressive disorders. Altering concentrations of one of the principal endocannabinoids, N‐arachidonoylethanolamine, also known as anandamide (AEA) can affect depressive‐like behaviors through several mechanisms including anti‐inflammatory, hormonal, and neural circuit alterations. Recently, isoflavonoids, a class of plant‐derived compounds, have been of therapeutic interest given their ability to modulate the metabolism of the endogenous ligands of the ECS. To determine the therapeutic potential of isoflavonoids, we screened several candidate compounds (Genistein, Biochanin‐A, and 7‐hydroxyflavone) in silico to determine their binding properties with fatty acid amide hydrolase (FAAH), the primary degrative enzyme for AEA. We further validated the ability of these compounds to inhibit FAAH and determined their effects on depressive‐like and locomotor behaviors in the forced swim test (FST) and open field test in male and female mice. We found that while genistein was the most potent FAAH inhibitor, 7‐hydroxyflavone was most effective at reducing immobility time in the forced swim test. Finally, we measured blood corticosterone and prefrontal cortex AEA concentrations following the forced swim test and found that all tested compounds decreased corticosterone and increased AEA, demonstrating that isoflavonoids are promising therapeutic targets as FAAH inhibitors.

The association of Curcuma and Scutellaria plant extracts improves laying hen thermal tolerance and egg oxidative stability and quality under heat stress conditions

Chronic exposure to high ambient temperatures is detrimental to laying hen performance and egg quality. Plant secondary metabolites may alleviate effects, partly due to their antioxidant activities. Herein, we investigated the effects of dietary supplementation with a phytonutrient solution (PHYTO) consisting of a plant extract combination of Scutellaria baicalensis and Curcuma longa on young layers (25–32 wk of age) raised under naturally elevated temperature conditions. Four hundred, 24-wk-old Lohmann hens were allocated in 50 cages and, after a week of adaptation, were offered a diet either containing 2 g/kg of PHYTO or not, for 8 wk. Hen BW was measured at the beginning and end of the trial, and egg production and feed intake were recorded weekly. At week 32, four eggs per cage were collected to determine egg quality characteristics as well as the rate of lipid and albumen oxidation in fresh eggs. At the end of the trial, two hens per cage were blood sampled for assessment of biochemical markers, one of which was euthanized for histopathological evaluation of the liver and intestine and assessment of intestinal histomorphometry. The herbal mixture supplementation significantly increased egg production rate at weeks 28 and 29 and for the overall production period, and feed efficiency at weeks 26–29. In addition, the degree of liver necrosis and microvascular thrombosis was lower (P < 0.05) whereas intestinal villosity was greater in duodenal and jejunal segments (P < 0.05) in the PHYTO compared to the control group. Supplementation also reduced (P < 0.05) blood concentrations of corticosterone, alanine aminotransferase activity, and TBARS, and a reduction in catalase activity was observed. Egg quality characteristics were not affected, except for eggshell thickness, egg diameter, and eggshell breaking strength that were superior in the PHYTO group (P < 0.05). PHYTO supplementation significantly improved egg lipid oxidation status of fresh eggs. In conclusion, supplementation with PHYTO improved laying hen productivity and egg quality, which was associated with an improvement in laying hen thermotolerance.

Glucose tolerance of iguanas is affected by high-sugar diets in the lab and supplemental feeding by ecotourists in the wild.

There is great interspecific variation in the nutritional composition of natural diets, and the varied nutritional content is physiologically tolerated because of evolutionarily based balances between diet composition and processing ability. However, as a result of landscape change and human exposure, unnatural diets are becoming widespread among wildlife without the necessary time for evolutionary matching between the diet and its processing. We tested how a controlled, unnatural high glucose diet affects glucose tolerance using captive green iguanas, and we performed similar glucose tolerance tests on wild Northern Bahamian rock iguanas that are either frequently fed grapes by tourists or experience no such supplementation. We evaluated both short and longer-term blood glucose responses and corticosterone (CORT) concentrations as changes have been associated with altered diets. Experimental glucose supplementation in the laboratory and tourist feeding in the wild both significantly affected glucose metabolism. When iguanas received a glucose-rich diet, we found greater acute increases in blood glucose following a glucose challenge. Relative to unfed iguanas, tourist-fed iguanas had significantly lower baseline CORT, higher baseline blood glucose, and slower returns to baseline glucose levels following a glucose challenge. Therefore, unnatural consumption of high amounts of glucose alters glucose metabolism in laboratory iguanas with short-term glucose treatment and free-living iguanas exposed to long-term feeding by tourists. Based on these results and the increasing prevalence of anthropogenically altered wildlife diets, the consequences of dietary changes on glucose metabolism should be further investigated across species, as such changes in glucose metabolism have health consequences in humans (e.g. diabetes).

Impact of broiler breeder growth trajectory on plasma corticosterone concentration: a comparison of analytical methods

Blood concentration of corticosterone (CORT) is a measure of welfare in feed restricted broiler breeders. The RIA and ELISA have been routinely used for measuring CORT in blood, excreta, and feather. Due to the presence of some confounding factors in the aforementioned colorimetric enzyme reaction methods, some methodological difficulties have been attributed to those assays. The correlation between broiler breeder plasma CORT concentrations, measured using ELISA and a novel liquid chromatography-tandem mass spectrometry (LC-MS/MS) method, was the focus of the current study. A total of 36 broiler breeder pullets were used, of which 30 were randomly assigned to one of 10 unique growth trajectories, and 6 were assigned to an unrestricted group. We designed the growth trajectories using a 3-phase Gompertz growth model with 10 levels of BW gain in the prepubertal and pubertal growth phases, ranging from the breeder-recommended target BW (CON) to 22.5% higher (CON+22.5%), in 2.5% increments. The BW trajectories were applied to each individual bird using a precision feeding (PF) system, which collected BW and feed intake data. The birds were classified based on age at first egg (AFE), and 12 birds each having the highest and lowest AFE was selected for the CORT study. Then median photostimulation BW of the candidate birds was used to define the upper (heavy BW) and lower (standard BW) extremes, and plasma CORT levels were evaluated by ELISA and LC-MS/MS methods from their blood collected at 18, 20, 22, 24, and 26 wk of age. Concentrations of plasma CORT measured using ELISA method were highly correlated (r = 0.95; P < 0.001) with values measured using LC-MS/MS method, validating interchangeably usage of both methods to measure plasma CORT in broiler breeders. Plasma CORT levels were not affected by photostimulation BW or breeders' age, indicating same welfare status between the precision fed high and low BW groups.

Potential of MALDI TOF mass spectrometry for detection and quantification of corticosterone in the blood of loggerhead sea turtles

The endangered loggerhead sea turtles (Caretta caretta) are a relatively abundant sea turtle species in Madeiran waters, where they encounter various environmental stressors: from natural to anthropogenic. The physiological stress response is increased corticosterone (CS) level in the blood, achieving 2 ng/mL. Although there are various analytical methods for determining the CS concentration in turtle blood, most of them require tedious procedures for the preparation. In this work, we have tested the possibility of using matrix-assisted laser desorption and ionization time-of-flight mass spectrometry (MALDI TOF MS) for fast screening and detection of CS in blood from a turtle captured at the coast of Madeira Island. MALDI does not require sample derivatization and is suitable for low sample volume. The linearity, precision, and limit of detection and quantification with three organic MALDI matrices were investigated in this study. The signal-to-noise ratio of the CS-derived signal was used as a parameter for quantification. Isotopically labelled corticosterone was added as a correction factor at fixed concentration to achieve better linearity and precision. Our results demonstrate that this method has the potential for quantification of CS in turtle blood. However, the lowest concentration of CS extracted from plasma that was still detectable by MALDI TOF MS was about 0.04 mg/mL, which is about ten times higher than the expected CS concentration in blood.

Impact of Pre-transport Feed Withdrawal on Welfare and Meat Characteristics of European Quails

The objective of this study was evaluate whether pretransport feed withdrawal affects welfare, carcass, and meat characteristics of European quails. A total of 120 European quails were used, with an initial age of 15 days. Bird feed was removed before transport to the slaughterhouse at the following times, which characterised the different treatments: zero hours, three hours, six hours, nine hours and twelve hours. The transport took 54 minutes to cover 27 kilometres to a commercial slaughterhouse. The birds were slaughtered at 41 days of age. During bleeding, blood samples were collected. Blood glucose, total protein, albumin, uric acid, and corticosterone concentrations were measured. The carcasses and meat characteristics were measured. Poultry body weight decreased and blood glucose concentrations increased with the increase in feed withdrawal time. The treatments did not affect carcass weights. Carcass yields after three hours fasting were similar to those in the six hours and nine hours groups, indicating that gastrointestinal tracts were empty after the third hour. Meat quality was negatively affected (pH, lightness, water holding capacity, cooking loss) by the increase in feed withdrawal time; integrated parameters that characterise dark, firm, dry meat. Pre transport feed withdrawal time should be three hours to empty the gastrointestinal tract and minimise losses in meat quality of European quails. It is necessary to adjust feed withdrawal so that it does not exceed this time, since there is no technical justification for supporting it.

Effects of two pesticides on northern leopard frog (Lithobates pipiens) stress metrics: Blood cell profiles and corticosterone concentrations

Amphibians are declining globally. Exposure to pesticides has been implicated in decreasing amphibian immune function, thus increasing their susceptibility to parasites and disease and thereby negatively affecting individuals and populations. Amphibians are likely exposed to neonicotinoids because these widely used insecticides are highly soluble in water and because amphibian freshwater habitats are often embedded in agroecosystems. Herein, we investigate the effects of long-term exposure to two individual neonicotinoids (clothianidin or thiamethoxam) at either low or high concentrations (2.5 or 250 µg/L) on northern leopard frog (Lithobates pipiens) blood cell profiles and concentrations of corticosterone, an energy-mediating hormone associated with stress. Larval frogs from Gosner stage 25 to 46 were exposed to pesticide and control treatments in outdoor mesocosms. Corticosterone concentrations were measured after 6 d of exposure, and blood cell profiles were assessed once frogs reached Gosner stage 46 (following 8 w of exposure). No significant changes were found in erythrocyte counts, leukocyte counts, monocyte to leukocyte ratios or corticosterone concentrations between treatments. However, exposure to either 2.5 or 250 µg/L of clothianidin, or 250 µg/L of thiamethoxam decreased neutrophil to lymphocyte ratios and neutrophil to leukocyte ratios, and exposure to 2.5 µg/L of clothianidin or 250 µg/L of thiamethoxam decreased eosinophil to leukocyte ratios. Our results indicate that long-term exposure to neonicotinoids can alter leukocyte profiles, indicative of a stress response. Future studies should investigate whether chronic exposure to neonicotinoids affect multiple measures of stress differently or influences the susceptibility of amphibians to parasites and pathogens. Our work underscores the importance of continued use of multiple measures of stress for different amphibian species when undertaking ecotoxicological assessments.

The Impact of Temperature and Humidity on the Performance and Physiology of Laying Hens.

Simple SummaryThe present study investigated whether the temperature-humidity index (THI) influences the production parameters and physiology of laying hens. Two environmental conditions combining high temperature with low relative humidity (TLHH75) or vice versa (THHL75), with the same THI value (75), were considered. The same THI value indicated equal thermal stress for laying hens. Neither TLHH75 nor THHL75 affected laying performance, including egg production, egg weight, and egg mass, feed intake, feed conversion ratio, plasma biochemical parameters, and stress indicators. Our study suggests that laying hens exposed to the same THI values will receive similar thermal stresses. The results of this study will serve as a scientific basis for management decisions and handling laying hens under thermally challenging conditions.We investigated the effect of different ambient temperatures and relative humidity (RH) with the same temperature-humidity indices (THI) on laying performance, egg quality, heterophil to lymphocyte ratio (H/L ratio), corticosterone (CORT) concentration in blood, yolk, and albumen, and plasma biochemical parameters of laying hens. Commercial hens (Hy-Line Brown; n = 120), aged 60 weeks, were allocated to two environmental chambers. Laying hens were subjected to either one of two thermal treatments—26 °C and 70% RH (TLHH75) or 30 °C and 30% RH (THHL75) for 28 days—with the same THI of 75. Neither TLHH75 nor THHL75 affected laying performance, including egg production, egg weight, egg mass, feed intake, and feed conversion ratio (p > 0.05). Plasma biochemical parameters such as total cholesterol, high-density lipoprotein cholesterol, triglycerides, calcium, magnesium, and phosphorus were not altered by the environmental treatments (p > 0.05). As for stress indicators, both environmental regimes failed to affect blood H/L ratio and CORT levels in plasma, yolk, and albumen (p > 0.05), although albumen CORT levels were elevated (p < 0.05) in TLHH75 group at day 7. Hence, our study suggests that laying hens performed and responded similarly when exposed to either TLHH75 or THHL75 characterized by the same THI. These results can serve as a scientific basis for management decisions and handling laying hens under thermally challenging conditions.

Characteristics of the Functional State of the Hypothalamo-Hypophyseal-Adrenocortical System in Krushinskii–Molodkina Rats

The aims of the present work were to assess interstrain differences in the functional state of the hypothalamo-hypophyseal-adrenocortical system (HHACS) in intact Wistar rats and the Krushinskii–Molodkina (KM) strain, which constitutes a genetic model of reflex audiogenic epilepsy and to analyze the dynamics of changes in the HHACS in KM rats during and after convulsive seizures. The results show that KM rats display a reduced level of activity of corticoliberinergic neurons due to an increase in the inhibitory influence of GABAergic neurons. The anterior lobe of the hypophysis showed increases in proopiomelanocortin (POMC) and adrenocorticotrophic hormone (ACTH) contents. Basal blood ACTH and corticosterone levels in KM and Wistar rats were no different. Thus, these data provide evidence of impairments to the interaction of the hypothalamus and hypophysis in KM rats, which may evidently be among the possible mechanisms supporting the maintenance of blood hormone concentrations at levels characteristic of control rats of the maternal Wistar strain. Single convulsive seizures in KM rats led to increases in corticoliberin and vasopressin release in the portal circulation and ACTH in the systemic circulation at the clonic-tonic stage, which developed 6–10 sec after the moment of presentation of the sound signal. A prolonged increase in the blood corticosterone level lasting 24 h was seen. Sound stimulation with the same parameters in Wistar rats did not lead to any significant changes in ACTH or blood corticosterone concentrations. Thus, the data obtained here suggest a specific nature of HHACS activation in KM rats due to the propagation of epileptiform activity in the brain; the results provide evidence of the involvement of the HHACS in mediating convulsive activity.

The effect of an enriched laying environment on welfare, performance, and egg quality parameters of laying hens kept in a cage system

The aim of this study was to evaluate the welfare and performance of laying hens kept in a furnished cage system equipped with additional feeders. A total of 72 Lohmann Brown hens were randomly assigned to 4 experimental groups. Each group consisted of 6 cages housing 3 birds per cage (18 birds per group). Group I was a control group without an extra feeder in the cages. Experimental groups GII, GIII, and GIV contained one, 2, and 3 additional feeders in the cages, respectively. The assessment of bird welfare was based on production, physiological and behavioral parameters, as well as on the basis of external appearance. The experiment lasted 12 wk. The obtained results suggest that enriching laying hens’ cages with additional feeders improved the welfare of the hens. Enrichment of cages significantly reduced the number of feather pecking and aggressive behaviors in the GII and GIV groups (P < 0.01) and the GIII group (P < 0.05). Breast plumage was significantly (P < 0.05) better in the GII group compared with that in the control group. The control group also had the worst general plumage (P < 0.01). The GII and GIV groups were also characterized by significantly (P < 0.05) lower blood corticosterone concentrations compared with the control group. No negative changes in egg production and quality parameters were observed in the experimental groups. Only eggs from the GIV group had significantly (P < 0.05) lower breaking strength than those from the control and GII group. The results suggest that the best solution is to place 1 additional feeder in furnished laying hens’ cages.

Susceptibility and resilience to chronic social defeat stress in adolescent male mice: No correlation between social avoidance and sucrose preference

Psychosocial stress is the major form of stress faced by children and adolescents and is an important risk factor for the development of mental illnesses. Chronic social defeat stress (CSDS) is a preclinical mouse model that induces an entire spectrum of phenotypes with similar interindividual variability as seen in humans. Following CSDS, adult male mice have been characterized as being either susceptible or resilient to emotional stress on the basis of their social interactions, which was reported to be highly correlated with sucrose preference (SP) when measured after the last defeat episode.We studied adolescent male C57BL/6 mice (30 days old) for susceptibility and resilience to social avoidance, anhedonia and anxiety-like behaviors, body weight change and basal blood corticosterone concentrations after 10 days of CSDS. Defeated adolescents showed reduced SP, reduced social interaction time (with an unknown adolescent male from their same strain), reduced weight gain and higher basal blood corticosterone concentration when compared to nondefeated mice. Only a small proportion of defeated adolescents were either totally susceptible (20%) or totally resilient (30%) in both the SP and social avoidance tests. The remaining defeated mice had a distinct behavioral impairment - susceptible in one test and resilient in the other. Surprisingly, behaviorally resilient defeated adolescents were the most affected population in terms of both endocrine/physiological outcomes. These findings illustrate that, contrary to prior assumptions in adults, the CSDS responses are more complex and singular in adolescents, and caution should be taken for the correct interpretation of those phenotypes. We propose a better characterization of social defeat stress responses as a critical step to advance our understanding of the mechanisms behind stress resilience that translate to human experience.

Intestinal microbial ecology, immune response, stress indicators, and gut morphology of male broiler chickens fed low-phosphorus diets supplemented with phytase, butyric acid, or Saccharomyces boulardii

Six dietary treatments were applied in a 42-d study to determine the effect of phytase, butyric acid, and S. boulardii on productive performance, intestinal microflora, immune response, stress indicators, and gut morphology in broiler chickens fed diets with reduced content of nonphytate P (nPP). On d 0, a total of 750 male broiler chickens were randomly allotted to 6 treatments with 5 pens of 25 broiler chickens for each diet: positive control (PC, adequate amounts of nPP), negative control (NC, 0.1% reduction in dietary nPP content), NC + 500 FTU phytase/kg (PHY), NC + 2 g butyric acid/kg (BA), NC + 1 × 108 cfu S. boulardii /kg (SB), and NC + butyric acid + S. boulardii (BA + SB). Considering the entire study period, body weight gain in broiler chickens fed any of the diets were greater (P < 0.05) than in broiler chickens fed the NC diet, where the broiler chickens fed diets PHY and BA + SB had the greatest value. Broiler chickens fed diets PC, PHY, SB, and BA + SB had greater (P < 0.05) relative thymus weight, primary and secondary antibody response against infectious bronchitis virus vaccine, and cutaneous basophil hypersensitivity to phytohaemagglutinin-P, but lower (P < 0.05) mortality rate and blood corticosterone concentration than those fed the NC diet at d 42. Feeding diet BA + SB increased (P < 0.05) cecal Lactobacillus spp. counts (d 35) and jejunal villus high:crypt depth (d 42), but decreased (P < 0.05) cecal Clostridium spp. counts (d 35) compared with those fed the NC diet. On d 35, the PHY, BA, SB, and BA + SB treatments had also the lower (P < 0.05) population of E. coli and Clostridium spp. in the ileum. No diets affected feed intake, relative weights of abdominal fat and liver, the population of total anaerobic bacteria, Bifidobacterium spp., and Coliforms in both ileum and ceca, serum insulin concentration, and duodenal morphology. In conclusion, the combination of butyric acid and S. boulardii may have synergistic effects on improving productive performance, immune response, intestinal microflora, and gut morphology in broiler chickens fed the low-nPP diet.