Plasma Corticosterone Concentrations Research Articles

3,5-Dihydroxy-4-methoxybenzyl alcohol, a novel antioxidant isolated from oyster meat, inhibits the hypothalamus–pituitary–adrenal axis to regulate the stress response

BackgroundAntioxidants that can scavenge reactive oxygen in the brain and inhibit hyperactivity of the HPA axis are desirable. AimsWe investigated the cerebral translocation of the antioxidant 3,5-dihydroxy-4-methoxybenzyl alcohol (DHMBA) and the effects of DHMBA administration on the hypothalamus–pituitary–adrenal (HPA) axis in stress-loaded rats. MethodsExperiment 1: Plasma and brain DHMBA concentrations were measured over time after oral DHMBA administration to female B6 mice. Experiment 2: Female Wistar Imamichi rats were used. The normal group was not subjected to stress. The stress, DHMBA, and vitamin E groups were subjected to individual and overcrowding stress. Brain and hippocampal 8-hydroxy-2′-deoxyguanosine levels, hippocampal glucocorticoid receptor-α levels, plasma corticosterone levels and RNA levels of glutathione peroxidase 4, catalase, and glutathione reductase in the hippocampus were measured. ResultsIn Experiment 1, DHMBA was not detected in the plasma or brain before DHMBA administration but was detected in both after administration. In Experiment 2, brain and hippocampal 8-hydroxy-2′-deoxyguanosine levels and plasma corticosterone levels were significantly lower in the DHMBA than in the stress group. Glucocorticoid receptor-α levels were higher in the DHMBA than in the stress group. DHMBA increased RNA levels of antioxidant enzymes in the hippocampus. Conclusion: DHMBA was translocated to the brain after administration. DHMBA administration decreased 8-hydroxy-2′-deoxyguanosine levels in the brain and hippocampus, increased hippocampal glucocorticoid receptor-α levels, and decreased the plasma corticosterone concentration, suggesting that DHMBA inhibits hyperactivity of the HPA axis. Nrf2 pathway activity induced by DHMBA resulted in increased antioxidant enzyme levels in the hippocampus

12484 Safety And Pharmacokinetics Of Anti-ACTH Antibody Lu AG13909 In Patients With Classic Congenital Adrenal Hyperplasia: Phase 1 Open-label, Multiple-Ascending-Dose Trial Protocol

Abstract Disclosure: U. Srirangalingam: Advisory Board Member; Self; Lundbeck. Consulting Fee; Self; Diurnal. Research Investigator; Self; Neurocrine. A. Velusamy: Consulting Fee; Self; Novo Nordisk. M. Binderup: Employee; Self; H. Lundbeck A/S. B. Baker: Employee; Self; H. Lundbeck A/S. M. Folden Flensburg: Employee; Self; H. Lundbeck A/S. L. Pickering Boserup: Employee; Self; H. Lundbeck A/S. J. Luthman: Employee; Self; H. Lundbeck A/S. H. Benecke: Employee; Self; H. Lundbeck A/S. R.J. Auchus: Consulting Fee; Self; Neurocrine Biosciences, Diurnal, Corcept Therapeutics, Recordati Rare Diseases, Crinetics Pharmaceuticals, Quest Diagnostics, Xeris Pharmaceuticals, Novo Nordisk, H. Lundbeck A/S, Sparrow Pharmaceuticals. Research Investigator; Self; Adrenas Therapeutics, Spruce Biosciences, Neurocrine Biosciences, Diurnal, Corcept Therapeutics, Recordati Rare Diseases, Crinetics Pharmaceuticals. Introduction: Classic congenital adrenal hyperplasia (CAH) is a rare, autosomal recessive disorder characterized by cortisol and aldosterone deficiency, elevated adrenocorticotropic hormone (ACTH) and subsequent hyperandrogenemia, most commonly due to 21-hydroxylase deficiency. Balancing physiological glucocorticoid replacement and control of hyperandrogenism remains a challenge with the risk of long-term consequences of glucocorticoid overtreatment. Lu AG13909 is a novel, high-affinity, anti-ACTH monoclonal antibody that neutralizes ACTH-induced signaling. In preclinical models, Lu AG13909 dose-dependently and persistently reduced plasma corticosterone and cortisol concentrations. No adverse effects were observed after 6 months of intravenous dosing every 2 weeks in cynomolgus monkeys. Here, we describe the ongoing first-in-human trial of Lu AG13909, investigating the safety, tolerability, pharmacokinetic (PK) properties, and pharmacodynamic (PD) effects of Lu AG13909 in adults with classic CAH. Methods: This is a Phase 1, open-label, multiple-ascending-dose trial with intra-participant dose escalation (EUCT #2023-503711-15-00). The trial enrolls men and women with classic CAH aged between ≥18 and ≤70 years under stable glucocorticoid and mineralocorticoid dosing, with morning 17-hydroxyprogesterone >4 times the upper limit of normal. Each participant receives up to 6 doses of Lu AG13909 every 28-35 days at increasing dose levels. The trial consists of 2 parts: Part A has a 3+3 design, in which 3 participants are given a certain dose, and escalation to the next dose is based on a 28-day safety observation period. Part B explores the pharmacologically relevant Lu AG13909 doses identified in Part A in a larger number of participants. The aim is for a total of 12 participants to receive each of the dose levels identified as relevant. Outcomes The primary safety and tolerability endpoints include adverse events and clinical safety tests. PK endpoints include maximum observed exposure and area under the Lu AG13909 concentration-time curve in a dosing interval. The PD endpoints are the relative reductions in morning 17-hydroxyprogesterone, androstenedione, and unbound ACTH, from baseline to the day after each Lu AG13909 dose. Conclusions This innovative, multi-dose, intra-participant dose escalation trial design was developed specifically for the rare classic CAH population, who have a high unmet medical need due to the challenges with current glucocorticoid treatment. The aim of the trial is to gather safety, PK, and PD data while minimizing participant risk and burden. Data from this trial will reinforce the development of Lu AG13909 as a novel treatment strategy in conditions characterized by increased levels of ACTH, such as classic CAH and Cushing disease. Presentation: 6/3/2024

The effect of dietary supplementation of a Bacillus-based direct fed-microbial on Pekin duck subjected to heat stress challenge

Limited research investigating the use of direct-fed microbials (DFM) to mitigate the effects of heat stress in Pekin ducks exists. This study evaluated the use of a DFM at different inclusion rates. Treatments included commercial-type basal diet (CON), or CON supplemented with 125, 250, 500, or 750 ppm DFM. On d 21–35, ducks were subjected to a cyclic heat stress challenge for 12 h/d. Performance, gait scores, footpad lesions, complete cell blood counts, total plasma corticosterone concentrations, fear testing, bone health, litter quality, and gut health were measured. Body weight on d 35 was lower for CON (p < 0.05) than all other treatments. Feed conversion (d 15–35) was higher (p > 0.05) in CON than all other treatments. Total plasma corticosterone concentrations and heterophil to lymphocyte ratios were greater for CON (p < 0.05) compared to all other treatments, indicating lower stress susceptibility in DFM treatments. The CON had lower villus height (p < 0.05) than the 125 and 250 ppm DFM treatments. There was a quadratic response observed with 500 ppm as the peak in performance and stress measures indicating it may be the optimum. These results indicate that DFM supplementation during heat stress can improve duck performance and welfare.

Disparate Effects of Stressors on Met-Enkephalin System Parameters and on Plasma Concentrations of Corticosterone in Young Female Chickens.

The effects of stressors were examined on Met-enkephalin-related parameters and plasma concentrations of corticosterone in 14-week-old female chickens. Water deprivation for 24 h was accompanied by a tendency for increased plasma concentration of Met-enkephalin while plasma concentrations of corticosterone were elevated in water-deprived birds. Concentrations of Met-enkephalin were reduced in the anterior pituitary gland and adrenal gland in water-deprived pullets while proenkephalin (PENK) expression was increased in both tissues. There were changes in the plasma concentrations of Met-enkephalin and corticosterone in pullets subjected to either feed withholding or crowding. Concentrations of Met-enkephalin were increased in the anterior pituitary gland but decreased in adrenal glands in pullets subjected to crowding stress. The increase in the plasma concentrations of Met-enkephalin was ablated when the chickens were pretreated with naltrexone. However, naltrexone did not influence either basal or crowding on plasma concentrations of corticosterone. In vitro release of Met-enkephalin from the anterior pituitary or adrenal tissues was depressed in the presence of naltrexone. It was concluded that Met-enkephalin was part of the neuroendocrine response to stress in female chickens. It was concluded that stress influenced the release of both Met-enkephalin and corticosterone, but there was not complete parallelism.

Evidence-Based Severity Assessment of Animal Models for Pancreatic Cancer.

Animal models are crucial to preclinical oncological research and drug development. Animal experiments must be performed in accordance with the 3R principles of replacement and reduction, if possible, and refinement where these procedures remain crucial. In addition, European Union legislations demand a continuous refinement approach, as well as pro- and retrospective severity assessment. In this study, an objective databased severity assessment was performed in murine models for pancreatic cancer induced by orthotopic, subcutaneous, or intravenous injection of Panc02 cells. Parameters such as body weight change, distress score, perianal temperature, mouse grimace scale, burrowing, nesting behavior, and the concentration of corticosterone in plasma and its metabolites in feces were monitored during tumor progression. The most important parameters were combined into a score and mapped against a reference data set by the Relative Severity Assessment procedure (RELSA) to obtain the maximum achieved severity for each animal (RELSAmax). This scoring revealed a significantly higher RELSAmax for the orthotopic model than for the subcutaneous and intravenous models. However, compared to animal models such as pancreatitis and bile duct ligation, the pancreatic cancer models are shown to be less severe. Data-based animal welfare assessment proved to be a valuable tool for comparing the severity of differently induced cancer models.

Dysregulation of circadian clock gene expression patterns in a treatment-resistant animal model of depression.

Circadian rhythm (CR) disturbances are among the most commonly observed symptoms during major depressive disorder, mostly in the form of disrupted sleeping patterns. However, several other measurable parameters, such as plasma hormone rhythms and differential expression of circadian clock genes (ccgs), are also present, often referred to as circadian phase markers. In the recent years, CR disturbances have been recognized as an essential aspect of depression; however, most of the known animal models of depression have yet to be evaluated for their eligibility to model CR disturbances. In this study, we investigate the potential of adrenocorticotropic hormone (ACTH)-treated animals as a disease model for research in CR disturbances in treatment-resistant depression. For this purpose, we evaluate the changes in several circadian phase markers, including plasma concentrations of corticosterone, ACTH, and melatonin, as well as gene expression patterns of 13 selected ccgs at 3 different time points, in both peripheral and central tissues. We observed no impact on plasma corticosterone and melatonin concentrations in the ACTH rats compared to vehicle. However, the expression pattern of several ccgs was affected in the ACTH rats compared to vehicle. In the hippocampus, 10 ccgs were affected by ACTH treatment, whereas in the adrenal glands, 5 ccgs were affected and in the prefrontal cortex, hypothalamus and liver 4 ccgs were regulated. In the blood, only 1 gene was affected. Individual tissues showed changes in different ccgs, but the expression of Bmal1, Per1, and Per2 were most generally affected. Collectively, the results presented here indicate that the ACTH animal model displays dysregulation of a number of phase markers suggesting the model may be appropriate for future studies into CR disturbances.

Study of heart rate and corticosterone variability in the simulation of rhino-surgical interventions in biological objects.

Aims: to assess changes in the time range of heart rate variability (HRV) and plasma corticosterone concentration in rats after simulating septoplasty. Materials and methods: a septoplasty was simulated in 30 mature male Wistar rats weighing 210-290 g. An ECG was recorded with subsequent analysis of the time domain of HRV, as well as blood sampling for changes in the concentration of corticosterone in the blood plasma. Results: SDNN significantly increased in comparison with the control on days 2 and 3 (p &lt;0.001), but decreased on days 4-5 (p &lt;0.001) and 6 days (p &lt;0.01 ). rMSSD changed in waves with two irregular peaks on days 1 and 6. SDNN / rMSSD, in comparison with the 1st day of the postoperative period, increased on the 2nd day and continued to grow (p &lt;0.05), and on the 4th day it began to decrease (p &lt;0.01). The total power of HRV was low throughout the postoperative period (p &lt;0.001), except for the 3rd day, when it was equal to the control data. The increase in the total power indicator fell on the 3rd day after the operation (p &lt;0.01), after which its decline occurred again. The concentration of corticosterone in the blood plasma in rats was significantly higher than before (p &lt;0.001). From the 2nd to the 4th postoperative day, its plateau was determined. Conclusion: Simulation of septoplasty leads to changes in the time range of HRV, an increase in the concentration of corticosterone in the blood plasma in rats with its maximum at the time of surgery and after 24 hours, the formation of a "plateau" from the 2nd to the 4th postoperative days, which coincides with changes of HRV.

3 The impact of early-life cecal microbiota transplantation on injurious behaviors in egg-laying chickens

Abstract Injurious behaviors in laying hens are a critical issue facing the poultry egg industry. Recent studies have shown that the gut microbiota influences host brain function and behavioral characteristics in humans and various animals. In laying hens, it has been reported that injurious behaviors (such as aggression, feather pecking and cannibalism) are associated with dysregulation of the microbiota-gut-brain axis. To further interrogate the role of the microbiota-gut-brain axis on bird behavior, we used two inbred layer chicken lines, 63 and 72 (line 72 displays more aggressive behavior), and transferred pooled cecal contents from either line to day of hatch chicks. Cecal microbiota transplantation (CMT) from each line was conducted once daily, by gavage, from d 1 to 10, then boosted once weekly from wk 3 to 5. We hypothesized that the cecal microbiota composition and animal behavior in recipient birds would be similar to that of their donor animals because of the microbiota-gut-brain axis. Microbial communities were compared using 16S rRNA gene amplicon sequencing, behavior was recorded in home cages as well as in paired aggression tests, and physiological measurements were taken from brain tissue and blood to measure levels of neurotransmitters and immune function. When examining the differences in the donor birds, hypothalamic serotonin and tryptophan concentrations were greater for line 63 compared with line 72 birds (P &amp;lt; 0.05). Plasma corticosterone, heterophil/lymphocyte ratios, and central norepinephrine concentrations were less for line 63 birds (P &amp;lt; 0.05). Cecal microbial diversity was not statistically different between the lines, but many bacterial taxa were differentially abundant between the two lines. After cecal transplantation, 63-CMT (recipient) birds displayed less aggressive behavior with a greater hypothalamic serotonergic activity at wk 5, similar to donor birds. Correspondingly, two amplicon sequence variants (ASVs) belonging to Lachnospiraceae and one Ruminococcaceae UCG-005 ASV were positively correlated with the concentrations of brain tryptophan and serotonin, respectively. Along with greater aggression, 72-CMT birds seemed to have greater physical growth traits (increased body weight, ileal villus/crypt; P ≤ 0.05), but decreased concentrations of brain norepinephrine and dopamine, and the greatest ileal serotonin turnover in the ileum at wk 5 (P &amp;lt; 0.05). ASVs belonging to Mollicutes RF39 and GCA-900066225 in 72-CMT birds were negatively correlated with the brain 5-hydroxyindoleacetic acid (5-HIAA) at wk 5, and one Bacteroides ASV was negatively correlated with plasma serotonin at wk 16. Meanwhile, 63-CMT birds potentially had better gut health and immune function (greater concentrations of ileal mucosal secretory IgA, plasma IL-10; P &amp;lt; 0.05). These results suggest linkages among serotonergic activity, stress response, innate immunity, and gut microbiota populations and that CMT could be a novel strategy for reducing aggressive behavior through regulating signaling along the microbiota-gut-brain axis.

Comparison effects of Natural and Artificial lighting on selected blood physiological variables of broilers grown to 56 days of age

Light is one of the major enviro-climatic factors in poultry houses that influences physiology and metabolic processes and impact poultry welfare, health, production and behaviors. This study compared the effects of natural and artificial lighting on selected blood physiological variables of broilers grown to 56 days of age. In each of the two trials, a total of 704 (352 males/352 females) 1-d- old Ross x Ross 708 chicks were obtained from a commercial hatchery on day of hatch. The design structure was a randomized complete block design with two treatments and eight replications per trial. Birds were equally and randomly distributed into 16 environmentally controlled rooms in groups of 44 (22 males/22 females) per room. Thus, each of the two treatments were represented by eight rooms with total of sixteen replicates. Temperature and RH on d 1 were maintained at 90 ± 2.1°F and 50 ± 5%, respectively across all treatments rooms. Temperature was decreased by 4 °F per week until it reached 66 °F at 56 d of age. Feed and water were provided ad libitum. Birds were provided a four phase-feeding program (Starter: 0-14 d, Grower: 15-28 d, Finisher: 29-42 d, and Withdrawal: 43-56 d). Blood samples (3 ml) were collected from the brachial wing vein of 3 males and 3 females birds per room on d 28, 42, and 56 which were then analyzed immediately for whole blood physiological variables. Blood plasma samples were analyzed for T3, T4, and corticosterone concentrations. Results showed that artificial light significantly increased sO2 (P &lt; 0.049), SaO2 (P &lt; 0.031), and decreased RHb (P &lt; 0.044) which may be due to slight difference in body weights, but the changes were all within physiological ranges for this species. In addition, blood glucose and plasma corticosterone concentrations were not affected by treatments, signify a similar level of physiological stress between the two light types. In conclusion, physiological variables examined in this study were unaffected by both natural and artificial lighting. However, birds exposed to artificial lighting had slightly increased body weight in comparison with birds reared under natural lighting, which may have a significant impact in commercial poultry production. USDA Agricultural Research Service. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Endocrine data provide further evidence of physiologic derangement in sea turtles affected by the Deepwater Horizon oil spill

This study was conducted to characterize the adrenocortical and thyroid status of Kemp’s ridley sea turtles Lepidochelys kempii that were affected by the Deepwater Horizon oil spill. A plasma aldosterone assay was validated for L. kempii, and it was used along with previously validated assays for corticosterone and free thyroxine to assess hormone concentrations of 30 L. kempii that were hospitalized due to oil exposure, representing 2 severities of oiling (lightly or heavily oiled). Hormone concentrations were also assessed in relation to 8 clinical biochemical analytes. Analysis of paired samples indicated that oiled turtles had significantly higher initial aldosterone and corticosterone concentrations, which declined during convalescence (average 96 and 90% decrease, respectively). Thyroxine concentrations significantly increased between admission and convalescence (average 65% increase). Initial biochemical data indicated significantly higher plasma potassium, ionized magnesium, and lactate concentrations compared to convalescent values. Aldosterone concentrations were positively correlated with corticosterone, negatively correlated with free thyroxine, and variably correlated with several clinical biochemical analytes. Results of this study indicate that L. kempii had robust adrenocortical activity after oiling, capture, and transport to the hospital, regardless of the degree of oiling, resulting in very high plasma concentrations of aldosterone and corticosterone. This study also confirms that aldosterone can be reliably measured in sea turtle plasma samples, providing another diagnostic tool for the physiologic assessment of this Critically Endangered species.

Research Note: Morphine influences circulating and tissue concentrations of met-enkephalin and proenkephalin (PENK) expression and plasma concentrations of corticosterone in chickens

The effects of the administration of the opioid agonist, morphine, on plasma and tissue concentrations of Met-enkephalin were determined in 14 wk old female chickens. In addition, effects of morphine on proenkephalin (PENK) expression were examined. Plasma concentrations of Met-enkephalin were reduced 10 minutes after morphine administration. Plasma concentrations of peptides that contain Met-enkephalin motifs were decreased 30 minutes after morphine administration. Tissue concentrations of Met-enkephalin tended to be depressed following morphine administration. Adrenal concentrations of PENK peptides containing Met-enkephalin motifs were decreased in chickens challenged with morphine. Expression of PENK in the anterior pituitary gland and adrenal glands were decreased in morphine treated compared to control pullets. In contrast, plasma concentrations of corticosterone were elevated 10 min after morphine treatment. Morphine also induced changes in mu (µ) opioid receptors and delta (δ) opioid receptors in both anterior pituitary tissue and adrenal tissues.

Investigating the effect of parental pre-gestational stress on ethological parameters in male rat offspring

Investigating the effect of parental pre-gestational stress on ethological parameters in male rat offspring

CRF binding protein activity in the hypothalamic paraventricular nucleus is essential for stress adaptations and normal maternal behaviour in lactating rats

To ensure the unrestricted expression of maternal behaviour peripartum, activity of the corticotropin-releasing factor (CRF) system needs to be minimised. CRF binding protein (CRF-BP) might be crucial for this adaptation, as its primary function is to sequester freely available CRF and urocortin1, thereby dampening CRF receptor (CRF-R) signalling. So far, the role of CRF-BP in the maternal brain has barely been studied, and a potential role in curtailing activation of the stress axis is unknown.We studied gene expression for CRF-BP and both CRF-R within the paraventricular nucleus (PVN) of the hypothalamus. In lactating rats, Crh-bp expression in the parvocellular PVN was significantly higher and Crh-r1 expression in the PVN significantly lower compared to virgin rats. Acute CRF-BP inhibition in the PVN with infusion of CRF(6–33) increased basal plasma corticosterone concentrations under unstressed conditions in dams. Furthermore, while acute intra-PVN infusion of CRF increased corticosterone secretion in virgin rats, it was ineffective in vehicle (VEH)-pre-treated lactating rats, probably due to a buffering effect of CRF-BP. Indeed, pre-treatment with CRF(6–33) reinstated a corticosterone response to CRF in lactating rats, highlighting the critical role of CRF-BP in maintaining attenuated stress reactivity in lactation. To our knowledge, this is the first study linking hypothalamic CRF-BP activity to hypothalamic-pituitary-adrenal axis regulation in lactation. In terms of behaviour, acute CRF-BP inhibition in the PVN under non-stress conditions reduced blanket nursing 60 min and licking/grooming 90 min after infusion compared to VEH-treated rats, while increasing maternal aggression towards an intruder. Lastly, chronic intra-PVN inhibition of CRF-BP strongly reduced maternal aggression, with modest effects on maternal motivation and care.Taken together, intact activity of the CRF-BP in the PVN during the postpartum period is essential for the dampened responsiveness of the stress axis, as well as for the full expression of appropriate maternal behaviour.

Father’s Absence in the Mongolian gerbil (Meriones unguiculatus) is associated with alterations in paternal behavior, T, cort, presence of ERα, and AR in mPOA/ BNST

Testosterone (T), estrogen receptor alpha (ERα), and androgen receptor (AR) play a significant role in the regulation of paternal behavior. We determined the effects of deprivation of paternal care on alterations in paternal behavior, T concentrations in plasma, and the presence of ERα and AR in the medial preoptic area (mPOA), bed nucleus of the stria terminalis (BNST), medial amygdala (MeA), and olfactory bulb (OB), as well as the corticosterone (CORT) concentrations in plasma caused by deprivation of paternal care in the Mongolian gerbil (Meriones unguiculatus). Twenty pairs of gerbils were formed; the pups were deprived of paternal care (DPC) in 10 pairs. In another 10 pairs, the pups received paternal care (PC). Ten males raised in DPC condition and 10 males raised in PC conditions were mated with virgin females. When they became fathers, each DPC male and PC male was subjected to tests of paternal behavior on day three postpartum. Blood samples were obtained to quantify T and CORT concentrations, and the brains were removed for ERα and AR immunohistochemistry analyses. DPC males gave less care to their pups than PC males, and they had significantly lower T concentrations and levels of ERα and AR in the mPOA and BNST than PC males. DPC males also had higher CORT concentrations than PC males. These results suggest that in the Mongolian gerbil father’s absence causes a decrease in paternal care in the offspring, which is associated with alterations in the neuroendocrine mechanisms that regulate it.

Effects of Restraint Stress on Circulating Corticosterone and Met Enkephalin in Chickens: Induction of Shifts in Insulin Secretion and Carbohydrate Metabolism.

This study examined the effects of acute restraint stress in the presence or absence of naltrexone on the circulating concentrations of insulin, glucose, Met-enkephalin and corticosterone in 14-week-old chickens [design: 2 sex × 2 stress/non-stress × 2 +/- naltrexone]. In chickens (five male and five females per treatment) subjected to restraint for 30 min, there were increases in the plasma concentrations of corticosterone and Met-enkephalin. The plasma concentrations of insulin and glucose were also increased in the chickens during restraint. Moreover, there were increases in the plasma concentrations of insulin and glucose in the chickens. The patterns of expression of the proenkephalin gene (PENK) in both the anterior pituitary gland and the adrenal gland were very similar to that of plasma Met-enkephalin. There were relationships between the plasma concentrations of corticosterone, Met-enkephalin, insulin and glucose after 30 min of restraint. The effects of naltrexone treatment on both untreated and stressed chickens were also examined, with naltrexone attenuating the stress-induced increases in the plasma concentrations of corticosterone, Met-enkephalin and glucose but not in those of insulin. The present study demonstrates that stress increases insulin secretion in chickens but also induces insulin resistance.

Husbandry Protocols for Juvenile Loggerhead Sea Turtles (Caretta caretta) Based on Stress Response to Stocking Density and Dry-Dock Time

ABSTRACT When necessary, sea turtles are held captive for veterinarian care and research purposes. Protocols and basic guidelines have been described for husbandry of sea turtles with veterinarian needs but not considering physiological indicators of animal welfare. Because all sea turtle are imperiled species, monitoring their welfare is important. The aim of this study was to standardize husbandry protocols for loggerhead (Caretta caretta) juveniles held under seminatural conditions, based on circulating concentration of plasma corticosterone (Cort) and behavior. Two experiments were performed to analyze physiological and behavioral responses of the animals facing changes in stocking density and different dry-docking times. Cort analyses suggested that the number of animals per tank can be modified occasionally, without affecting their health and welfare. However, dry-docking time should be < 30 min, as indicated by the significant elevation of circulating Cort at ≥ 30 min, rising from 1.51- ng/ml to 5.28-ng/ml. Protocols tested did not affect behavioral responses, except for the breaths per move, which increased while Cort increased, despite differences exhibited by experimental animals in behavioral responses according to daily times (morning vs afternoon) and the sex of the animals.

Maternally derived avian corticosterone affects offspring genome-wide DNA methylation in a passerine species.

Avian embryos develop in an egg composition which reflects both maternal condition and the recent environment of their mother. In birds, yolk corticosterone (CORT) influences development by impacting pre- and postnatal growth, as well as nestling stress responses and development. One possible mechanism through which maternal CORT may affect offspring development is via changes to offspring DNA methylation. We sought to investigate this, for the first time in birds, by quantifying the impact of manipulations to maternal CORT on offspring DNA methylation. We non-invasively manipulated plasma CORT concentrations of egg-laying female zebra finches (Taeniopygia castanotis) with an acute dose of CORT administered around the time of ovulation and collected their eggs. We then assessed DNA methylation in the resulting embryonic tissue and in their associated vitelline membrane blood vessels, during early development (5 days after lay), using two established methods - liquid chromatography-mass spectrometry (LC-MS) and methylation-sensitive amplification fragment length polymorphism (MS-AFLP). LC-MS analysis showed that global DNA methylation was lower in embryos from CORT-treated mothers, compared to control embryos. In contrast, blood vessel DNA from eggs from CORT-treated mothers showed global methylation increases, compared to control samples. There was a higher proportion of global DNA methylation in the embryonic DNA of second clutches, compared to first clutches. Locus-specific analyses using MS-AFLP did not reveal a treatment effect. Our results indicate that an acute elevation of maternal CORT around ovulation impacts DNA methylation patterns in their offspring. This could provide a mechanistic understanding of how a mother's experience can affect her offspring's phenotype.

Adrenalectomy attenuates hyperalgesia but does not regulate muscle wasting in a female rat model of fibromyalgia.

Although it is well established that fibromyalgia (FM) syndrome is characterized by chronic diffuse musculoskeletal hyperalgesia, very little is known about the effect of this pathology on muscle tissue plasticity. Therefore, the present study aimed to characterize the putative alterations in skeletal muscle mass in female rats subjected to a FM model by inducing chronic diffuse hyperalgesia (CDH) through double injections of acidic saline (pH 4.0) into the left gastrocnemius muscle at 5-day intervals. To determine protein turnover, the total proteolysis, proteolytic system activities and protein synthesis were evaluated in oxidative soleus muscles of pH 7.2 (control) and pH 4.0 groups at 7 days after CDH induction. All animals underwent behavioural analyses of mechanical hyperalgesia, strength and motor performance. Our results demonstrated that, in addition to hyperalgesia, rats injected with acidic saline exhibited skeletal muscle loss, as evidenced by a decrease in the soleus fibre cross-sectional area. This muscle loss was associated with increased proteasomal proteolysis and expression of the atrophy-related gene (muscle RING-finger protein-1), as well as reduced protein synthesis and decreased protein kinase B/S6 pathway activity. Although the plasma corticosterone concentration did not differ between the control and pH 4.0 groups, the removal of the adrenal glands attenuated hyperalgesia, but it did not prevent the increase in muscle protein loss in acidic saline-injected animals. The data suggests that the stress-related hypothalamic-pituitary-adrenal axis is involved in the development of hyperalgesia, but is not responsible for muscle atrophy observed in the FM model induced by intramuscular administration of acidic saline. Although the mechanisms involved in the attenuation of hyperalgesia in rats injected with acidic saline and subjected to adrenalectomy still need to be elucidated, the results found in this study suggest that glucocorticoids may not represent an effective therapeutic approach to alleviate FM symptoms.

Plasma and Shed-Skin Corticosterone Levels in a Population of Louisiana Pine Snakes (Pituophis ruthveni)

Abstract Measurement of corticosterone in various tissues has been used to investigate the stress response in reptile and amphibian species for decades. The tissue source from which corticosterone is measured reflects different periods of time and chronicity of stress levels in the subject, and different tissue collection methods differ in degree of invasiveness. Studies of corticosterone in keratinized tissues of reptiles, such as shed skin, are limited in number compared to hair and feather glucocorticoid studies in avian and mammalian species, but warrant continued research as they may reflect more different periods of time and chronicity of corticosterone levels than plasma or other tissues, and can be obtained in a minimally invasive manner. In this study, we measured corticosterone concentrations in both plasma and shed skin of Louisiana pine snakes (Pituophis ruthveni) that were all previously diagnosed with subclinical Cryptosporidium serpentis infection. We also tracked stressors experienced by different individuals to identify potential relationships between periods of increased stress and corticosterone levels in plasma and shed skin. There were no significant correlations between individual plasma and shed skin corticosterone levels, or between corticosterone levels in either tissue type and stressors experienced. This is the first study where corticosterone levels were measured in plasma and shed skin of P. ruthveni, and is the first known evaluation of plasma and shed skin corticosterone levels in a snake population previously testing positive for Cryptosporidium serpentis.

Metodologias para indicar estresse causado por jejum em poedeiras comerciais

ABSTRACT: Plasma corticosterone concentration (CORT), heterophil:lymphocyte ratio (H:L), catalase activity (CAT), total glutathione concentration (GSH), and thiobarbituric acid reactive substance levels (TBARS) were evaluated in 48 Hy-Line Brown laying hens, at 79 weeks of age, after being fasted for 10 consecutive days. Blood was collected on days zero, two, four, six, eight, and 10 of fasting, and a completely randomized design was adopted, with eight replicates on each day of collection, with each bird being an experimental unit. The time of maximum stress was determined for each method, using the polynomial regression analysis. The Pearson correlation analysis was also performed to determine whether the methods were interchangeable. CORT and GSH concentrations indicated that the time of maximum stress occurred at 4.3 days of fasting, whereas, the H:L and CAT activity indicated that the time of maximum stress occurred at 10 days of fasting. The malondialdehyde concentration detected by the TBARS method was highest at day zero and lowest at day 5.5 of fasting, but this method was not a reliable measure of stress. The low Pearson correlation coefficients observed among the methods made it impossible to designate only one of the tested methods as a replacement for the others, to measure the stress in laying hens during fasting.