Significant Increase In Corticosterone Research Articles

Metabolomics analysis of the effect of GnRH on the pregnancy rate of ewes with estrus synchronization scheme based on progesterone.

Gonadotropin-releasing hormone (GnRH) is widely used in the timed artificial insemination protocol for sheep. However, there remains a debate regarding its impact on pregnancy rates during artificial insemination. This study aims to evaluate the effect of GnRH on the pregnancy rates in Huyang ewes, analyze the pre-implantation metabolite changes caused by GnRH using metabolomics, and elucidate the mechanism effect on pregnancy rates. All ewes were administered a vaginal progesterone sponge containing 45 mg of flurogestone acetate for 12 days and received 330 units of equine chorionic gonadotropin (eCG) intramuscularly after sponge removal. The experimental group (n = 69) received an intramuscular treatment of 17 μg GnRH agonist triptorelin 48 h after sponge removal on Day 0, while the control group (n = 41) received 1 mL of sterile saline solution. All ewes underwent a single vaginal insemination 58 h after the withdrawal of the progesterone sponge. The difference in pregnancy rates between the two groups was calculated. Metabolomic analysis was performed on plasma samples collected on Day 7 after the treatment of GnRH agonist. Gonadotropin-releasing hormone (GnRH) treatment significantly reduced the pregnancy rate in the experimental group compared with the control group (72.2 vs. 82.9%, p < 0.05). Metabolomic analysis indicated that GnRH treatment affected metabolites involved in collagen synthesis and prostaglandin synthesis in the endometrial tissue, which includes a marked decrease in hydroxyproline amino acid content and a significant increase in corticosterone and prostaglandin D2 lipids and unsaturated fatty acids. In summary, the injection of GnRH agonist Triptorelin 48 h after progesterone sponges removal reduces the pregnancy rate of Huyang ewe following artificial insemination. It also affects the metabolite levels related to endometrial collagen and prostaglandin synthesis, harming embryo implantation.

Mechanism of skeletal muscle atrophy by muscle fiber types in male rats under long-term fasting stress

Fasting induces metabolic changes in muscles, which are differentiated by muscle fiber type. In this study, the mechanism of fasting-induced muscle atrophy in rats was examined to determine the differences between muscle fiber types in energy production. Fasting for 96 h did not alter the weight of the soleus (SOL), a fiber type I muscle, but did significantly reduce the weight of gastrocnemius (GM), a fiber type II muscle. GM, SOL and blood pregnenolone and testosterone levels decreased under fasting, which induced energy deprivation, whereas corticosterone (CORT) levels significantly increased. However, the expression of 3β-HSD and P45011β in GM was unaffected by fasting. The decrease in GM weight may be due to decreased levels of testosterone and reduced synthesis of mammalian target of rapamycin (mTOR). Significant increases in CORT both GM and SOL were associated with increases in the amount of branched-chain amino acids available for energy production. However, decreased levels of mTOR and IGF1 and increased levels of CORT and IL-6 in SOL suggest that GM proteolysis was followed by SOL proteolysis for additional energy production. In conclusion, IGF1 levels decreased significantly in SOL, whereas those of IL-6 significantly increased in SOL and blood but decreased in GM. Blood branched-chain amino acids (BCAA) levels were unaffected due to fasting, whereas an increase was noted in the levels of BCAA in GM and SOL. These results show that fasting for 96 h restricts energy supply, producing fast-twitch muscle atrophy followed by slow-twitch muscle atrophy.

Environmental pollution and nutritional quality modulate immune response of the wood mouse (Apodemus sylvaticus) through hormonal disturbances

Cadmium (Cd) and lead (Pb) are known to enhance immune cell damages and to decrease cellular immunity, promoting higher susceptibility to infectious diseases. Selenium (Se) is an essential element involved in immunity and reactive oxygen species scavenging. This study aimed at evaluating how Cd and Pb and low nutritional (Se) quality modulate immune response to a bacterial lipopolysaccharide (LPS) challenge in wood mice (Apodemus sylvaticus). Mice were trapped near a former smelter in northern France in sites of High or Low contamination. Individuals were challenged immediately after capture or after five days of captivity, fed a standard or a Se-deficient diet. Immune response was measured with leukocyte count and plasma concentration of TNF-α, a pro-inflammatory cytokine. Faecal and plasma corticosterone (CORT), a stress-hormone involved in anti-inflammatory processes, was measured to assess potential endocrine mechanisms. Higher hepatic Se and lower faecal CORT were measured in free-ranging wood mice from High site. LPS-challenged individuals from High site showed steeper decrease of circulating leukocytes of all types, higher TNF-α concentrations, and a significant increase of CORT, compared to individuals from Low site. Challenged captive animals fed standard food exhibited similar patterns (decrease of leukocytes, increase of CORT, and detectable levels of TNF-α), with individuals from lowly contaminated site having higher immune responses than their counterparts from highly polluted site. Animals fed Se-deficient food exhibited lymphocytes decrease, no CORT variation, and average levels of TNF-α. These results suggest (i) a higher inflammatory response to immune challenge in free-ranging animals highly exposed to Cd and Pb, (ii) a faster recovery of inflammatory response in animals lowly exposed to pollution when fed standard food than more exposed individuals, and (iii) a functional role of Se in the inflammatory response. The role of Se and mechanisms underlying the relationship between glucocorticoid and cytokine remain to be elucidated.

Handling and restraint induce a significant increase in plasma corticosterone in Hispaniolan Amazon parrots (Amazona ventralis).

To measure baseline plasma corticosterone levels in Hispaniolan Amazon parrots (Amazona ventralis) and assess the effects of handling and restraint on corticosterone levels over 1 hour, reflective of what parrots might experience during veterinary care. 10 male and 12 female Hispaniolan Amazon parrots. Each parrot was removed from its cage and wrapped in a towel for restraint similar to that performed in a clinical setting. An initial baseline blood sample was collected in < 3 minutes upon entrance into the parrot room, after which blood samples were taken every 15 minutes for 1 hour (a total of 5 blood samples). An enzyme-linked immunoassay was validated for Hispaniolan Amazon parrots and used to determine concentrations of plasma corticosterone. On average, parrots showed a significant increase in corticosterone between baseline samples and all subsequent postrestraint time points (average baseline corticosterone ± SD: 0.51 ± 0.65 ng/mL). Females, on average, displayed significantly higher corticosterone levels than males after 30, 45, and 60 minutes of restraint (P = .016, P = .0099, and P = .015, respectively). Birds with feather-destructive behavior did not have significantly higher corticosterone levels than birds without the condition (P = .38). Understanding the physiological stress response in companion psittacine birds during routine handling will allow clinicians to better evaluate how this may affect the patient's condition and diagnostic test results. Assessing how corticosterone correlates to behavioral conditions such as feather-destructive behavior will provide clinicians with the potential to develop treatment options.

Relation between Heat Stress and Some Hormones in Alloxan Induced Diabetic Rats

The current study carried out to evaluate the levels of corticosterone, epinephrine, insulin and thyroxine accompanied induced diabetes mellitus in rats. Therefore, ninty six rats were divided into two main groups: control group which exposed to normal temperature (21±2) °C and second group which exposed to high temperature (40±2)°C each main group subdivided into three subgroups exposed to temperature for one, two and four hours respectively, also each subgroup composed of healthy rats and diabetic rats equally. At the end of experiment blood samples were collected for determination of corticosterone epinephrine, insulin and thyroxine. Results revealed significant increase in corticosterone and epinephrine and insulin in heat stressed group compared with control group while there was significant decrease in thyroxine in healthy and diabetic rats in heat stressed group compared with control group.Results showed significant increase in corticosterone in diabetic rats compared with healthy rats in both groups ,while the significant increase in epinephrine and insulin in diabetic rats was only in heat stressed group.Results reported significant decrease in corticosterone and thyroxine according to the increase in heat exposure duration,while epinephrine and insulin increased according to the duration. These findings indicated that heat stress may be increase harmful effects in alloxan induced diabetic rats.

Relation between Heat Stress and Some Hormones in Alloxan Induced Diabetic Rats

The current study carried out to evaluate the levels of corticosterone, epinephrine, insulin and thyroxine accompanied induced diabetes mellitus in rats. Therefore, ninty six rats were divided into two main groups: control group which exposed to normal temperature (21±2) °C and second group which exposed to high temperature (40±2)°C each main group subdivided into three subgroups exposed to temperature for one, two and four hours respectively, also each subgroup composed of healthy rats and diabetic rats equally. At the end of experiment blood samples were collected for determination of corticosterone epinephrine, insulin and thyroxine. Results revealed significant increase in corticosterone and epinephrine and insulin in heat stressed group compared with control group while there was significant decrease in thyroxine in healthy and diabetic rats in heat stressed group compared with control group.Results showed significant increase in corticosterone in diabetic rats compared with healthy rats in both groups ,while the significant increase in epinephrine and insulin in diabetic rats was only in heat stressed group.Results reported significant decrease in corticosterone and thyroxine according to the increase in heat exposure duration,while epinephrine and insulin increased according to the duration. These findings indicated that heat stress may be increase harmful effects in alloxan induced diabetic rats.

Lesion of the dorsal hippocampus alters the time-course evolution of corticosterone rise in the ventral hippocampus after stress.

We previously showed that an acute stress-induced an early corticosterone rise in the dorsal hippocampus (dHPC) and a delayed one in the ventral hippocampus (vHPC). Congruently, we hypothesized that the dHPC may influence the time-course evolution of poststress glucocorticoid rise in the vHPC. To probe this issue, we performed ibotenic acid lesions of the dHPC and measured by microdialysis the time-course evolution of corticosterone rise in the vHPC after an acute stress delivery. In nonstress condition, we showed that the dHPC lesion induced a significant increase of corticosterone both in plasma and in the vHPC. In addition, an acute stress (electric footshocks) induced a faster and more sustained corticosterone rise in the vHPC of dHPC-lesioned animals, as compared to sham-operated ones. This study provides new found evidence to the effect that the dHPC lesion alters the time-course evolution of corticosterone rise within the vHPC after stress.

Effects of commercial hatchery processing on short- and long-term stress responses in laying hens

In commercial egg production, chicks are exposed to a potentially stressful procedure during their first day of life. Here, we investigated how this procedure affects the chickens in a short- as well as long-term perspective by conducting two behaviour tests and measuring corticosterone (CORT) and sex hormone levels at different time points. These results were compared with a group of control chickens from the same hatchery and incubator that did not go through the commercial hatchery routine. Chickens were continuously weighed, egg production data was collected and feather scoring was performed. We found that chicks have a significant increase in CORT during the hatchery process, which implies they are exposed to stress. During first weeks of life, these chicks were more fearful, had a higher CORT reactivity during restraint and weighed more than control chicks. Later in life, hatchery treated chickens had more feather damages and injuries on combs and wattles, a faster onset of egg laying and higher levels of estradiol. We conclude that processing at the commercial hatchery was a stressful event with short- and long-term effects on behaviour and stress reactivity, and potentially also positive effects on production. The results are relevant for a large number of individuals, since the chicken is by far the globally most common farm animal.

The Effect of Prenatal Stress on Auditory Brainstem Responses in Rat Pups

Background: Recent epidemiological evidence indicates that the fetal environment can influence susceptibility to later disease during the lifespan. Prenatal stress exposure alters the programming of the metabolic and endocrine balance of various organs, including the auditory system. Objectives: The current study aimed at evaluating how prenatal stress influences Auditory Brainstem Responses. Methods: Eighteen pregnant Wistar rats were stressed during a one-month gestation by chronic mild stress (CMS, a variable schedule of different stressors). After birth, the offspring’s hearing thresholds and latencies were evaluated and compared with the control group. The hearing thresholds were assessed by recording auditory evoked brainstem responses to 4, 8,12, and 16 kHz tone burst. Results: The results showed that although CMS caused a significant increase in corticosterone in pregnant mothers, the offspring with CMS experience had significantly lower body weight than control animals (P < 0.00) yet there was no difference between hearing sensitivity of prenatally stressed offspring and the control group. However, ABRs showed a marked prolongation in wave II and IV latencies in prenatally stressed rats (P < 0.05). Conclusion: The current data confirmed that prenatal exposure to mild stress is not detrimental to hearing sensitivity. However, these data suggest that prenatal stress can affect the temporal processing of auditory stimuli in the brainstem.

Measuring corticosterone concentrations over a physiological dynamic range in female rats

Accurate assessment of plasma corticosterone, the primary stress hormone in rodents, is an essential part of characterizing the stress response in experimental animals. To this end, both enzyme-linked immunosorbent assay (ELISA) and radioimmunoassay (RIA) remain widely used. However, considerable assay-specific variability exists among commercially available corticosterone assays due to differing assay principles, detection methods, range, and sensitivity. While technical comparisons of commercially available corticosterone assays have previously been conducted, the ability to detect acute stress-induced endocrine changes has not been compared among these methods to date. Using the forced swim test, a commonly utilized behavioral paradigm in rodents as a physiologically-relevant acute stress challenge, we compared four commercial corticosterone assays – three ELISA kits and one RIA kit – in their ability to detect corticosterone across a dynamic range of both baseline and acute swim stress-driven concentrations. While all methods yielded results that were consistent at measuring relative differences between samples, only two of the four assays evaluated detected a statistically significant increase in corticosterone in rats exposed to acute swim stress compared to rats at baseline. The ELISA kit from Enzo Life Sciences demonstrated the greatest percent increase in plasma corticosterone from baseline to acute stress conditions. The RIA kit from MP Biomedicals also detected a significant corticosterone increase and yielded higher concentrations of corticosterone both at baseline and in the acute stress condition relative to the other three assays. We conclude that choice of assay can impact interpretation of data due to differences in efficacy across a dynamic range of physiological concentrations of corticosterone.

CORRECTION OF DISTURBED NEUROIMMUNE INTERACTIONS IN EXPERIMENTAL TRAUMATIC BRAIN INJURY BY MEANS OF RECOMBINANT INTERLEUKIN 2

Traumatic brain injury (TBI) commonly proceeds as a severe disease with high morbidity that can lead to neurological disorders in some of these patients. TBI is associated by multidirectional abnormalities of immune system, which affect quantity and functions of T-, B-, and NK-lymphocytes leading to infectious complications or autosensibilization. Restoration of the disturbances in neuroimmune interactions after TBI may be achieved by means of immunomodulators that have neuroprotective properties and may potentially initiate regenerative CNS activity. IL-2 is a cytokine that possesses neurooperative and neuroprotective properties. In immune system, IL-2 is produced by T-cells in response to antigen stimuli; in CNS, by brain cells. Lack of IL-2 production by both T-lymphocytes and brain cells increases a possibility of autoimmune and inflammatory pathologies. The objective of present study was to evaluate possible effects of human recombinant IL-2 (rIL-2, Roncoleukin®, Biothech Ltd., Russia) upon state and correction of immune and neuro-endocrine TBI consequences. The study was performed in adult Wistar rats. Mechanical TBI was produced by the dropping load model. 72 hours after inflicting the TBI, r-IL-2, at dose 30 mg/kg was injected once a day for three times. The animals from control group received 0.15M NaCl solution over the same period. The results have shown that, within first hours and days after TBI, corticosterone levels showed a sharp increase, whereas testosterone concentrations were decreased.In parallel, an increase in cytotoxic and proliferative activity of splenocytes was revealed, as well as increased number of splenocytes at their late apoptotic stage. Three daily injections of rIL-2 resulted into a significant increase in corticosterone and testosterone levels in injured animals on the day 7 after TBI. The animals treated with rIL-2 have exhibited more rapid normalization of cytotoxic and proliferative activity of splenocytes and return to normal ratio of proliferating splenocytes vs. apoptotic cells. Therefore, usage of rIL-2 may correct neuro-endocrine and immune interaction disturbances after TBI and decrease risk of chronic neurological disorders in TBI patients.

Different implications of the dorsal and ventral hippocampus on contextual memory retrieval after stress.

This study assessed the relative contributions of dorsal (dHPC) and ventral (vHPC) hippocampus regions in mediating the rapid effects of an acute stress on contextual memory retrieval. Indeed, we previously showed that an acute stress (3electric footschocks; 0.9mA each) delivered 15min before the 24h-test inversed the memory retrieval pattern in a contextual discrimination task. Specifically, mice learned in a four-hole board two successive discriminations (D1 and D2) varying by the color and texture of the floor. Twenty-four hours later, nonstressed animals remembered accurately D1 but not D2 whereas stressed mice showed an opposite memory retrieval pattern, D2 being more accurately remembered than D1. We showed here that, at the time of memory testing in that task, stressed animals exhibited no significant changes neither in pCREB activity nor in the time-course evolution of corticosterone into the vHPC; in contrast, a significant decrease in pCREB activity and a significant increase in corticosterone were observed in the dHPC as compared to nonstressed mice. Moreover, local infusion of the anesthetic lidocaine into the vHPC 15 min before the onset of the stressor did not modify the memory retrieval pattern in nonstress and stress conditions whereas lidocaine infusion into the dHPC induced in nonstressed mice an memory retrieval pattern similar to that observed in stressed animals. The overall set of data shows that memory retrieval in nonstress condition involved primarily the dHPC and that the inversion of memory retrieval pattern after stress is linked to a dHPC but not vHPC dysfunction.

Evaluation of the neutrophil:lymphocyte ratio as an indicator of chronic distress in the laboratory mouse.

When evaluating the effect of husbandry and biomethodologies on the well-being of laboratory mice, it is critical to utilize measurements that allow the distinguishing of acute stress from chronic stress. One of the most common measurements of stress in laboratory animals is the corticosterone assessment. However, while this measurement provides a highly accurate reflection of the animal's response to acute stressors, its interpretation is more prone to error when evaluating the effect of chronic stress. This study evaluated the use of the neutrophil:lymphocyte (NE:LY) ratio as an assessment of chronic stress in male and female C57Bl/6N mice as compared to serum corticosterone. One group of mice was exposed to mild daily stressors for 7 days, while the control group was handled with normal husbandry. The NE:LY ratio and serum corticosterone levels were significantly elevated in the chronically stressed mice, though a significant increase in corticosterone was only significant in males when compared by sex. The chronically stressed mice also demonstrated significantly fewer entries into the open arms and less time spent in the open arms of the elevated plus maze, suggesting that the mild daily stressors had induced a state of distress. The findings of this study confirm that the NE:LY ratio is a valid measurement for chronic stress in the laboratory mouse. However, these assays do not distinguish between distress or eustress, so behavioral and physiological assessments should always be included to determine a complete assessment of the well-being of the mouse.Supplementary informationThe online version of this article (doi:10.1038/laban.1298) contains supplementary material, which is available to authorized users.

Respiratory Effects and Systemic Stress Response Following Acute Acrolein Inhalation in Rats.

Previous studies have demonstrated that exposure to the pulmonary irritant ozone causes myriad systemic metabolic and pulmonary effects attributed to sympathetic and hypothalamus-pituitary-adrenal (HPA) axis activation, which are exacerbated in metabolically impaired models. We examined respiratory and systemic effects following exposure to a sensory irritant acrolein to elucidate the systemic and pulmonary consequences in healthy and diabetic rat models. Male Wistar and Goto Kakizaki (GK) rats, a nonobese type II diabetic Wistar-derived model, were exposed by inhalation to 0, 2, or 4 ppm acrolein, 4 h/d for 1 or 2 days. Exposure at 4 ppm significantly increased pulmonary and nasal inflammation in both strains with vascular protein leakage occurring only in the nose. Acrolein exposure (4 ppm) also caused metabolic impairment by inducing hyperglycemia and glucose intolerance (GK > Wistar). Serum total cholesterol (GKs only), low-density lipoprotein (LDL) cholesterol (both strains), and free fatty acids (GK > Wistar) levels increased; however, no acrolein-induced changes were noted in branched-chain amino acid or insulin levels. These responses corresponded with a significant increase in corticosterone and modest but insignificant increases in adrenaline in both strains, suggesting activation of the HPA axis. Collectively, these data demonstrate that acrolein exposure has a profound effect on nasal and pulmonary inflammation, as well as glucose and lipid metabolism, with the systemic effects exacerbated in the metabolically impaired GKs. These results are similar to ozone-induced responses with the exception of lung protein leakage and ability to alter branched-chain amino acid and insulin levels, suggesting some differences in neuroendocrine regulation of these two air pollutants.

Effect of Scoparia dulcis on noise stress induced adaptive immunity and cytokine response in immunized Wistar rats

BackgroundNoise acts as a stressor and is reported to have impact on individual health depending on nature, type, intensity and perception. Modern medicine has no effective drugs or cure to prevent its consequences. Being an environmental stressor noise cannot be avoided; instead minimizing its exposure or consuming anti-stressor and adaptogens from plants can be considered. ObjectivesThe present study was carried out to evaluate the anti-stressor, adaptogen and immunostimulatory activity of Scoparia dulcis against noise-induced stress in Wistar rat models. Material and methodsNoise stress in rats was created by broadband white noise generator, 100 dB A/4 h daily/15 days and S. dulcis (200 mg/kg b.w.) was administered orally. 8 groups of rats were used consisting of 6 animals each; 4 groups for unimmunized and 4 groups for immunized. For immunization, sheep red blood cells (5 × 109 cells/ml) were injected intraperitoneally. ResultsSub-acute noise exposed rats showed a significant increase in corticosterone and IL-4 levels in both immunized and unimmunized rats whereas lymphocytes, antibody titration, soluble immune complex, IL-4 showed a marked increase with a significant decrease in IL-2, TNF-α, IFN-γ cytokines only in unimmunized rats. Immunized noise exposed rats presented increased leukocyte migration index and decreased foot pad thickness, IL-2, TNF-α, IFN-γ with no changes in the lymphocytes. ConclusionS. dulcis (SD) has normalized and prevented the noise induced changes in cell-mediated and humoral immunity and it could be the presence of anti-stressor and immuno stimulant activity of the plant.

Evaluation of corticosterone and IL-1β, IL-6, IL-10 and TNF-α expression after 670-nm laser photobiomodulation in rats

The literature has shown that low-level laser therapy accelerates the repair of cutaneous wounds. However, there is a scarcity of scientific studies that characterise the possible systemic interference of laser photobiomodulation. The aim of this research was to quantitatively evaluate blood corticosterone levels and tissue cytokine expression in cutaneous wounds of rats treated with low-level laser therapy (semiconductor diode AsGaAl, continuous emission, 9mW, 670nm, 0.031W/cm(2), beam with an output area of 0.28cm(2)) and normal controls. A total of 36 male Wistar rats were used and randomly divided into two groups of 18 rats each. A standardised circular 6-mm-diameter wound was made in the dorsal skin region of each rat, and they were euthanised at 1, 6 and 12h after cutaneous surgery. The blood was collected, and portions of cutaneous tissue and subcutaneous muscle were removed and cryopreserved. Corticosterone levels in the blood were measured by a radioimmunoassay technique; histological sections were submitted to the ELISA technique for analysis of tissue cytokine expression levels. At 6h after surgery, a significant increase in corticosterone and a significant reduction in the levels of IL-1β and IL-6 in tissues of irradiated wounds were observed when compared to controls (p < 0.05). The levels of TNF-α and IL-10 expression were not significantly different between the groups at different time intervals. Thus, this study strongly suggests a systemic and local biomodulation of low-level laser therapy as indicated by the blood levels of corticosterone and the tissue expression of IL-1β and IL-6, respectively.

The Absence of Somatotroph Proliferation During Continuous Stress is a Result of the Lack of Extracellular Signal‐Regulated Kinase 1/2 Activation

The integrity of homeostasis can be affected by chronic stress, and hyposomatotropism is evident in chronic stress-associated illnesses. In the present study, we demonstrated that a continuous stress (CS) severely affected somatotrophs among hormone-secreting cells in the anterior lobe (AL) of the pituitary by using a rat CS model. Among AL cells, the proliferation of somatotrophs was almost entirely suppressed in rats that had 3-5 days of CS (5dCS), although other hormone-secreting cells continued to proliferate. The cell size of somatotrophs was reduced at 5dCS (P<0.01), the number of secretory granules was increased at 3dCS (P<0.01) and serum growth hormone (GH) was on declining trend during 1 to 5dCS, suggesting that GH release was inhibited. GH-releasing hormone (GHRH) mRNA level in the arcuate nucleus was transiently decreased, whereas its receptor expression in the AL was significantly increased in CS rats. When 5dCS rats were injected with GHRH, transient GH secretion was observed, whereas proliferation of somatotrophs did not occur. The GHRH administration failed to stimulate extracellular signal-regulated kinase (ERK) 1/2 phosphorylation and the nuclear translocation of ERK in somatotrophs. These results suggest that somatotrophs of 5dCS rats expressed sufficient GHRH receptor, which could transfer a signal for GH release. However, the GHRH-induced proliferation signal was blocked somewhere between the receptor and ERK1/2. Because significant increase of corticosterone in the initial stage (the 1-3dCS) was observed in this model, the corticosterone may affect the signalling. Although the mechanism underlying the blockage of the proliferation signal in somatotrophs under CS remains unclear, these somatotrophic disorder, suggesting that the present animal model may be useful for understanding the molecular mechanisms of chronic stress-associated illnesses.

Corticosterone, cortisol, triglycerides, aspartate aminotransferase and uric acid plasma concentrations during foie gras production in male mule ducks (Anas platyrhynchos × Cairina moschata)

1. Corticosterone, cortisol, triglycerides, aspartate aminotransferase (AST) and uric acid (UA) plasma concentration were measured at 8 (7 days after group housing), 12 (after 7 days of force feeding) and 13 weeks of age (at slaughter after 12 days of force feeding), and 45 min after an adrenocorticotrophic hormone (ACTH) stimulation test at 8 weeks of age in 12 male mule ducks in an on-farm experiment. 2. No significant increase of corticosterone was found during the force-feeding period compared with the concentration after housing. 3. Comparison of corticosterone and cortisol values indicates that cortisol can be considered as a reliable acute stress indicator in future routine examinations. 4. Plasma concentrations of triglycerides and aspartate aminotransferase increased progressively from pre-force feeding period to slaughtering. 5. Plasma concentrations of uric acid increased from the start at 8 weeks of age to the mid-force feeding period but no difference was noticed between the mid-force feeding period and slaughtering. 6. It is concluded that acute stress induced by force-feeding is similar at the beginning and end of the commercial production of foie gras.

Neonatal lipopolysaccharide exposure impairs sexual development and reproductive success in the Wistar rat

We investigated, in rats, whether neonatal exposure to bacterial lipopolysaccharide (LPS) impairs sexual development, sexual decline, and reproductive behaviour in later life. Rats were administered either LPS (Salmonella enterica, serotype enteritidis, 0.05mg/kg, ip) or saline (equivolume) on days 3 and 5 postpartum. The immediate and long-term effect of treatment on HPA and HPG hormones, testicular morphology, and mating behaviour was assessed. Neonatal LPS exposure induced a significant increase in corticosterone compared to controls, as well as reduced testosterone and LH in males and LH in females immediately following neonatal drug exposure. Neonatal LPS exposure disrupted the normal weight-to-age ratio of puberty onset in males and females, and impaired sexual performance in adulthood. Reproductive function was reflected in significantly diminished sperm presence in rats that had received neonatal LPS. LPS-treated females exhibited LH suppression during puberty, and males demonstrated testosterone suppression in late adulthood. Testosterone and LH surges during mating were significantly reduced in adult offspring treated with LPS as neonates. Furthermore, animals exposed to neonatal LPS and subsequent stress in adulthood, exhibited significantly blunted corticosterone responses. Morphometric assessment of testes taken from neonates revealed reduced gonocyte genesis immediately following LPS exposure and increased seminiferous disorganisation of the epithelium in these animals in adulthood. This research demonstrates the long-term impact of neonatal bacterial exposure on reproductive success given that early life exposure to bacteria disrupted puberty onset and sexual performance. Associated changes in neuroendocrine functioning suggest a possible mechanism through which a subfertile phenotype may arise.

Cage mate separation in pair-housed male rats evokes an acute stress corticosterone response

Corticosterone (CORT) release from the adrenal glands in response to acutely stressful stimuli is well-characterized, however several non-experimental, environmental stressors can also engender a CORT response. The aim of this study was to investigate an acute activation of the HPA axis in pair-housed animals in response to separation. We observed a rapid significant increase in CORT in the animal remaining in the home cage following cage mate removal, that was not caused by cage opening and transient removal of cage mate. In addition, we examined this response in both control, non-stressed animals and in animals subjected to chronic variable stress (CVS) and found that although basal levels of CORT differed between control and CVS animals, there was no significant difference in the acute CORT levels between the control and CVS animals after separation, indicating that this environmental event is perceived as acutely stressful in both conditions. Furthermore, we examined the time course of CORT activation and found that CORT levels rapidly rise within minutes of separation peaking at 15 min and returning to baseline by 90 min. The results of this study demonstrate that separation can induce an acute stress response in the remaining cage mate measured by increased CORT and should be considered in molecular, behavioral, and electrophysiological studies.