Age-dependent effects of acute stress on the behavior, blood parameters, immunity, and enteric nerves of mice

The impact of stress on mental and digestive health has been extensively studied, with chronic stress being associated with various disorders. However, age-related differences in the response to acute stress, both behaviorally and physiologically, remain poorly understood. Therefore, this study aimed to develop a model to detect transient stress in mice of different ages. The stressor employed in our experiments was a restraint stress procedure, where mice were subjected to brief periods of immobilization to induce an acute stress response. Male C3H/HeN mice aged 3, 6, 12, and 30 weeks were subjected to acute restrain stress (ARS) by being placed in a 50 ml conical centrifuge tube for 15 min. Subsequently, their behavior, organ tissues, hematological parameters, cortisol concentration, and immune responses were assessed. Following ARS, the increased in time and entries into the center by the 12-week-old mice following stress. In comparison to mice of other ages, those aged 6 weeks demonstrated notable elevations in erythrocytes, platelets, hemoglobin, and hematocrit, all of which were influenced by the time-dependent changes and the recovery process of ARS. Blood corticosterone levels were substantially elevated in all age groups after ARS. Furthermore, ARS induced a notable increase in leukocytes, basophils, residential macrophages, and CD4+ T cells in all age groups except for 3-week-old mice. However, the number of monocyte-derived macrophages and CD8+ T cells did not change significantly. Additionally, mice aged 3 and 6 weeks demonstrated an increase in GFAP+ cells following ARS, whereas NeuN+ cells decreased across all ages. These results suggest that ARS has varying effects on the behavior, cortisol concentration, and quantity of blood cells as well as hepatic immune cells in mice of different ages. These age-dependent responses shed light on the complex interplay between stress and physiological systems and contribute to the broader understanding of stress-related diseases.

Global dynamics of a tuberculosis model with age-dependent latency and time delays in treatment

Since there exists heterogeneity in incubation periods of tuberculosis and a time lag between treatment and recovery. In this study, we develop a tuberculosis model that takes into account age-dependent latency and time delays in treatment to describe the transmission of tuberculosis. We first show that the solution semi-flow of the model is well-posed and has a global attractor [Formula: see text] within an infinite dimensional space [Formula: see text]. Then we define the basic reproduction number [Formula: see text] and prove that it determines the global dynamics of the model. If [Formula: see text], the global attractor [Formula: see text] reduces to the disease-free equilibrium state, indicating that the disease-free equilibrium state is globally asymptotically stable. When [Formula: see text], the semi-flow generated by the model is uniformly persistent, and there exists an interior global attractor [Formula: see text] for this uniformly persistent model. By constructing a suitable Lyapunov function and applying LaSalle's Invariance Principle, we show that the global attractor [Formula: see text] is reduced to the endemic equilibrium state, which means that the endemic equilibrium state is globally asymptotically stable. Based on the tuberculosis data in China from 2007 to 2020, we simulate the parameters and initial values of the proposed model. Furthermore, we calculate the sensitivity of [Formula: see text] to the parameters and find the most sensitive parameters to [Formula: see text]. Finally, we present an improved strategy to achieve the WHO's goal of reducing the incidence of tuberculosis by 90% by 2035 compared to 2015.

Effects of age on the neural correlates of encoding source and item information: An fMRI study

The effects of age on encoding-related neural activity predictive of accurate item and source memory judgments were examined with fMRI, with an a priori focus of the inferior frontal gyrus (IFG) and hippocampus. During a scanned study phase, young and older adults viewed a series of pictures of objects and made one of two judgments on each object. At test, which occurred outside of the scanner, an 'old/new' judgment on each test item was followed, for those items endorsed old, by a source judgment querying the study task. Neural activity predictive of accurate subsequent item and source memory judgments was identified in bilateral IFG, several other cortical regions and bilateral hippocampus. Cortical effects were graded in the young group (source > item > miss) but predicted item memory only in the older group. Hippocampal effects exclusively predicted source memory, and the magnitude of these effects did not reliably differ between the age groups. In the older group only, IFG and hippocampal encoding effects were positively correlated across participants with memory performance. Similar findings were evident in the extra-IFG regions demonstrating encoding effects. With the exception of the age-dependent relationship identified for hippocampal encoding effects, the present findings are broadly consistent with those from prior aging studies that employed verbal memoranda and tests of associative recognition. Thus, they extend these prior findings to include non-verbal materials and a different operationalization of episodic recollection. Additionally, the present findings suggest that the sensitivity in older adults of IFG encoding effects to subsequent memory performance reflects a more general tendency for cortical encoding effects to predict memory performance in this age group.

Age-dependent immune response in pigs against foot-and-mouth disease virus in vitro

Foot-and-mouth disease, one of the most contagious diseases in cloven-hoofed animals, causes significant economic losses. The pathogenesis of foot-and-mouth disease virus (FMDV) infection is known to differ with age of the animals. In this study, we aimed to reveal the difference in immunological response in the initial stage of FMDV infection between piglets and adult pigs. Peripheral blood mononuclear cells (PBMCs) were isolated from 3 piglets (8 weeks old) and 3 pigs (35 weeks old) that were not vaccinated against FMDV. O-type FMDV (2 × 10² median tissue culture infectious dose) was inoculated into porcine PBMCs and the cells were incubated at 37.0°C under 5% CO₂ for various time periods (0, 1, 3, 6, 12, 24, and 48 h). The total RNA was obtained from the FMDV-inoculated PBMCs after each time point, and the virus titer was investigated in these RNA samples. Furthermore, dynamics of mRNA expression of the six tested cytokines (interferon [IFN]-α, IFN-γ, ‎interleukin [IL]-6, IL-8, IL-10, and tumor necrosis factor [TNF]-α) in FMDV-inoculated porcine PBMCs were evaluated by time-series analysis to determine the differences, if any, based on the age of the pigs. The PBMCs of piglets contained the highest quantity of FMDV mRNA at 6 hours post-inoculation (hpi), and the PBMCs of pigs had the highest quantity of FMDV mRNA at 3 hpi. The mean cycle threshold-value in the PBMCs steadily decreased after the peak time point in the piglets and pigs (6 and 3 hpi, respectively). The dynamics of mRNA expression of all cytokines except TNF-α showed age-dependent differences in FMDV-inoculated PBMCs. The mRNA expression of most cytokines was more pronounced in the piglets than in the pigs, implying that the immune response against FMDV showed an age-dependent difference in pigs. In conclusion, within 48 hpi, the 8-week-old piglets responded more rapidly and were more sensitive to FMDV infection than the 35-week-old pigs, which could be associated with the difference in the pathogenesis of FMDV infection among the pigs. These results provide valuable insights into the mechanisms underlying the age-dependent differences in immune response in pigs against FMDV infection.

Superficial temperature distribution patterns before and after physical activity in school children are indicative for personalized exercise coaching and disease prevention

Background

Thermoregulation is highly individual and predictive for potentially cascading pathologies. Altered and deficient thermoregulation is considered an important diagnostic indicator which can be of great clinical utility for specialized screening programs and individualized prediction and prevention of severe pathologies triggered early in life.

Working hypothesis

Individual thermoregulation can be objectively assessed by thermovision camera before and after exercises in school children stratified by age and gender that may be of great clinical utility for personalized training early in life in the framework of 3P medicine.

Study design

In this study, 60 female and male primary school children were exposed to physical exercises in the form of 45-min general fitness training. The subjects under examination were stratified by age: group 1 (7-year-olds), group 2 (9-year-olds), and group 3 (12-year-olds). Superficial body temperature patterns were measured by means of thermovision camera before and immediately after exercises, as well as after the 15-min recovery time. Temperature patterns were analyzed in 12 areas of the body front and back, covering trunk and upper and lower limbs.

Results

The obtained results revealed an individual and age-depended difference in response of the body to exercises. The first measurement prior to exercise (measurement 1) revealed no statistically significant differences in the mean surface temperature of all analyzed areas between 7- and 9-year-old children. Further, 7- and 9-year-old children did not differ significantly in the mean temperature recorded in the trunk compared to the 12-year-old children. However, in 12-year-old children, statistically significant higher values of the mean temperature of the upper and lower limbs, were observed compared to the group of 7-year-olds and significantly higher values of the mean temperature of the lower limbs compared to the group of 9-year-olds. Immediately after exercises (measurement 2), a statistically significant decrease in the temperature was noted in all groups and in all areas of the body. The greatest temperature change was observed in 12-year-olds, while the least one was measured in the youngest subjects. The statistically significant relation between the average trunk temperature of 7-year-old and 12-year-old children was observed: lower values of the mean temperature of the front and back of the trunk were noted in the group of 12-year-old children compared to the group of 7-year-olds. A significantly lower average temperature of the back of the trunk compared to the youngest group was also recorded in 9-year-old children. The study performed after the 15-min recovery time (measurement 3) showed an increase in the average temperature of all analyzed areas. In all subjects, the mean temperature recorded in measurement 3 did not differ significantly from the initial ones (measurement 1, prior to exercises). Only the mean temperature of the trunk back of 12-year-old children was significantly lower after the rest period compared to the initial examination. In all groups, the temperatures after exercises followed by a 15-min recovery returned to the initial ones, except of the trunk backs of 12-year-old children, where the temperature was lower than before exercises.

Conclusions and expert recommendations in the framework of 3PM

Thermovision analysis is an effective tool to assess individual thermoregulation and to stratify school children for personalized exercise coaching. Body exercise-based disease prevention early in life is effective when tailored to the person: multi-parametric guidance for prescribing exercises individually is needed. Contextually, proposed individualized training approach should be adapted to the age-dependent particularities and individual thermoregulation.

Risk Assessment of Perfluorooctane Sulfonate (PFOS) using Dynamic Age Dependent Physiologically based Pharmacokinetic Model (PBPK) across Human Lifetime

The widespread use of Perfluorooctane sulfonate (PFOS) in everyday life, its long half-life, and the lipophilicity that makes it easily accumulate in the body, raises the question of its safe exposure among different population groups. There are currently enough epidemiological studies showing evidence of PFOS exposure and its associated adverse effects on humans. Moreover, it is already known that physiological changes along with age e.g. organ volume, renal blood flow, cardiac output and albumin concentrations affect chemicals body burden. Human biomonitoring cohort studies have reported PFOS concentrations in blood and autopsy tissue data with PFOS present in sensitive organs across all human lifespan. However, to interpret such biomonitoring data in the context of chemical risk assessment, it is necessary to have a mechanistic framework that explains show the physiological changes across age affects the concentration of chemical inside different tissues of the human body. PBPK model is widely and successfully used in the field of risk assessment. The objective of this manuscript is to develop a dynamic age-dependent PBPK model as an extension of the previously published adult PFOS model and utilize this model to predict and compare the PFOS tissue distribution and plasma concentration across different age groups. Different cohort study data were used for exposure dose reconstruction and evaluation of time-dependent concentration in sensitive organs. Predicted plasma concentration followed trends observed in biomonitoring data and model predictions showed the increased disposition of PFOS in the geriatric population. PFOS model is sensitive to parameters governing renal resorption and elimination across all ages, which is related to PFOS half-life in humans. This model provides an effective framework for improving the quantitative risk assessment of PFOS throughout the human lifetime, particularly in susceptible age groups. The dynamic age-dependent PBPK model provides a step forward for developing such kind of dynamic model for other perfluoroalkyl substances.

Age-dependent variations in haematological and serum biochemical parameters of domestic pigeons (Columba livia domestica)

In this study, the age-dependent variations in haematological and serum biochemical parameters of domestic pigeons were evaluated. Sixty apparently healthy domestic pigeons comprising 30 young (2–7 weeks of age) and 30 adult (>7 weeks of age) were sampled from local breeders. Blood was collected from each bird via brachial venipuncture and divided into 2 parts; one part dispensed into labeled tubes containing ethylenediaminetetraacetic acid as anticoagulant was processed for haematological analyses. The other part was dispensed into labeled plain tubes, serum harvested and processed for serum biochemical analyses. Results revealed overall packed cells volume (PCV), haemoglobin concentration (HGB) and red blood cells (RBC) of 42.97 ± 4.53%, 13.15 ± 1.82 g/dL and 3.63 ± 0.50 × 10¹²/L respectively. All haematological parameters except mean corpuscular haemoglobin (MCH), mean corpuscular haemoglobin concentration (MCHC) and lymphocyte count showed statistical (p < 0.05) differences between young and adult pigeons. Values recorded for serum total protein, albumin, globulin, serum/albumin ratio, urea, creatinine and urea/creatinine ratio were 4.32 ± 0.74 g/dL, 2.07 ± 0.30 g/dL, 2.25 ± 0.74 g/dL, 1.04 ± 0.43, 0.48 ± 0.33 mg/dL, 0.75 ± 0.52 mg/dL and 0.73 ± 0.51 respectively. Serum urea and creatinine concentrations were significantly (p < 0.05) higher in adult (0.62 ± 0.40; 1.04 ± 0.60 mg/dL) compared to young (0.34 ± 0.13; 0.47 ± 0.15 mg/dL) pigeons. This study therefore demonstrated age-dependent variations in haematological and serum biochemical parameters of domestic pigeons.

Age, Wound Size, and Position of Injury - Dependent Vascular Regeneration Assay in Growing Leaves

Recurring damage to the aerial organs of plants necessitates their prompt repair, particularly their vasculature. While vascular regeneration assays for aerial plant parts such as the stem and inflorescence stalk are well established, those for leaf vasculature remain unexplored. Recently, we established a new vascular regeneration assay in growing leaves and discovered the underlying molecular mechanism. Here, we describe the detailed stepwise method for the incision and regeneration assay used to study leaf vascular regeneration. By using a combination of micro-surgical perturbations, brightfield microscopy, and other experimental approaches, we further show that the age of the leaf as well as the position and size of the injury determine the overall success rate of regeneration. This easy-to-master vascular regeneration assay is an efficient and rapid method to study the mechanism of vascular regeneration in growing leaves. The assay can be readily combined with cellular and molecular biology techniques.

An improved sex-specific and age-dependent classification model for Parkinson's diagnosis using handwriting measurement

BACKGROUND AND OBJECTIVES

Diagnosis of Parkinson's with higher accuracy is always desirable to slow down the progression of the disease and improved quality of life. There are evidences of inherent neurological differences between male and females as well as between elderly and adults. However, the potential of such gender and age infomration have not been exploited yet for Parkinson's identification.

METHODS

In this paper, we develop a sex-specific and age-dependent classification method to diagnose the Parkinson's disease using the online handwriting recorded from individuals with Parkinson's (n = 37; m/f-19/18;age-69.3 ± 10.9yrs) and healthy controls (n = 38; m/f-20/18;age-62.4 ± 11.3yrs). A support vector machine ranking method is used to present the features specific to their dominance in sex and age group for Parkinson's diagnosis.

RESULTS

The sex-specific and age-dependent classifier was observed significantly outperforming the generalized classifier. An improved accuracy of 83.75% (SD = 1.63) with the female-specific classifier, and 79.55% (SD = 1.58) with the old-age dependent classifier was observed in comparison to 75.76% (SD = 1.17) accuracy with the generalized classifier.

CONCLUSIONS

Combining the age and sex information proved to be encouraging in classification. A distinct set of features were observed to be dominating for higher classification accuracy in a different category of classification.

Age-dependent hepatic alterations induced by a high-fat high-fructose diet

OBJECTIVE

The present study aimed to evaluate and clarify how the age at which the intake of a high-fat and high-fructose diet begins can affect animals' livers.

METHODS

Thirty-eight male wistar rats aged 6 and 12 weeks were fed a high-fat and high-fructose diet for 13 weeks. Inflammatory cytokines, hepatic glycogen, serum and hepatic triacylglycerol and pAkt protein content in the liver were assessed. Percentage of weight gained, and visceral adiposity were also evaluated.

RESULTS

Young animal presented increased hepatic triacylglycerol and decreased glycogen, while adult animals had no significant alterations regarding its contents. IL6 and IL10 to IL6 ratio were also altered in young animals exposed to HFHF, while adult animals fed with HFHF had only increases in TNF-α. Both groups which received HFHF had increased serum triacylglycerol and visceral adiposity. However, only young animals gained more relative weight and had greater final body weight, gains which were related to alterations found in hepatic triacylglycerol and glycogen.

CONCLUSION

Age of which consumption begins interferes in how the liver deals with an excess of nutrient and subsequent proinflammatory stimulation, leading to different phenotypes.

Pediatric physiology in relation to the pharmacokinetics of monoclonal antibodies

INTRODUCTION

Dose design for pediatric trials with monoclonal antibodies (mAbs) is often extrapolated from the adult dose according to weight, age, or body surface area. While these methods account for the size differences between adults and children, they do not account for the maturation of processes that may play a key role in the pharmacokinetics and/or pharmacodynamics of mAbs. With the same weight-based dose, infants and young children typically receive lower plasma exposures when compared to adults. Areas covered: The mechanistic features of mAb distribution, elimination, and absorption are explored in detail and literature-based hypotheses are generated to describe their age-dependence. This knowledge can be incorporated into a physiologically based pharmacokinetic (PBPK) modeling approach to pediatric dose determination. Expert opinion: As data from pediatric clinical trials become increasingly available, we have the opportunity to reflect on the physiologic drivers of pharmacokinetics, safety, and efficacy in children with mathematical models. A modeling approach that accounts for the age-related features of mAb disposition can be used to derive first-in-pediatric doses, design optimal sampling schemes for children in clinical trials and even explore new pharmacokinetic end-points as predictors of safety and efficacy in children.

A mouse model with age-dependent immune response and immune-tolerance for HBV infection

BACKGROUND

Viral clearance of human HBV infection largely depends on the age of exposure. Thus, a mouse model with age-dependent immune response and immune-tolerance for HBV infection was established.

METHODS

HBVRag1 mice were generated by crossing Rag1^-/- mice with HBV-Tg mice. Following adoptive transfer of splenocytes adult (8-9 weeks old) and young (3 weeks old) HBVRag1 mice were named as HBVRag-ReA and HBVRag-ReY mice respectively. The biochemical parameters that were associated with viral load and immune function, as well as the histological evaluation of the liver tissues between the two mouse models were detected. The immune tolerance of HBVRag-ReY mice that were reconstituted at the early stages of life was evaluated by quantitative hepatitis B core antibody assay, adoptive transfer, and modulation of gut microbiota with the addition of antibiotics.

RESULTS

HBVRag-ReA mice indicated apparent hepatocytes damage, clearance of HBsAg and production of HBsAb and HBcAb. HBVRag-ReY mice did not develop ALT elevation, and produced HBcAb and HBsAg. A higher number of hepatic CD8⁺ T and B cells promoted clearance of HBsAg in HBVRag-ReA mice following 30 days of lymphocyte transfer. In contrast to HBVRag-ReA mice, HBVRag-ReY mice exhibited higher levels of Th1/Th2 cytokines. HBVRag-ReY mice exhibited significantly higher (P < .01, approximately 10-fold) serum quantitative anti-HBc levels than HBV-Tg mice, which might be similar to the phase of immune clearance and immune tolerance in human HBV infection. Furthermore, the age-related tolerance in HBVRag-ReY mice that were sensitive to antibiotic treatment was different from that noted in HBV-Tg mice. GS-9620 could inhibit the production of HBsAg, whereas HBV vaccination could induce sustained seroconversion in HBVRag-ReY mice with low levels of HBsAg.

CONCLUSIONS

The present study described a mouse model with age-dependent immunity and immune-tolerance for HBV infection in vivo, which may mimic chronic HBV infection in humans.

Age predicts cytokine kinetics and innate immune cell activation following intranasal delivery of IFNγ and GM-CSF in a mouse model of RSV infection

Respiratory syncytial virus (RSV) is the leading cause of lower respiratory tract infections in young children and is further associated with increased healthcare utilization and cost of care in the first years of life. Severe RSV disease during infancy has also been linked to the later development of allergic asthma, yet there remains no licensed RSV vaccine or effective treatment. Pre-clinical and clinical studies have shown that disease severity and development of allergic asthma are associated with differences in cytokine production. As a result, stimulation of the innate host immune response with immune potentiators is gaining attention for their prospective application in populations with limited immune responses to antigenic stimuli or against pathogens for which vaccines do not exist. Specifically, macrophage-activating cytokines such as interferon gamma (IFNγ) and granulocyte colony-stimulating factor (GM-CSF) are commercially available immune potentiators used to prevent infections in patients with chronic granulomatous disease and febrile neutropenia, respectively. Moreover, an increasing number of reports describe the protective function of IFNγ and GM-CSF as vaccine adjuvants. Although a positive correlation between cytokine production and age has previously been reported, little is known about age-dependent cytokine metabolism or immune activating responses in infant compared to adult lungs. Here we use a non-compartmental pharmacokinetic model in naïve and RSV-infected infant and adult BALB/c mice to determine the effect of age on IFNγ and GM-CSF elimination and innate cell activation following intranasal delivery.

Study on age-dependent pre-existing 2009 pandemic influenza virus T and B cell responses from Chinese population

BACKGROUND

The outbreak of the 2009 H1N1 influenza pandemic (H1N1pdm) affected thousands of people in Mexico and the United States, and spread rapidly throughout the world from April 2009 to July 2010. To explore the age-specific prevalence of seroprotection against H1N1pdm infection, we estimated pre-existing humoral and cellular immunities of residents in Northern China against H1N1pdm and seasonal H1N1 virus in an age-dependent manner.

METHODS

Anonymous serum samples were collected from 1425 to 1434 adult healthy individuals before and after the pandemic outbreak, and then grouped by birth year 1913-1990. The antibody titers of H1N1pdm and seasonal H1N1 were determined using microneutralization (MN) assays, and the proportion of seropositive was estimated based on the year of birth. Separately, another 63 blood samples were collected in 2006 and prepared for analysis of virus specific memory B and IFN-γ⁺ T cells using the ELISpot assays.

RESULTS

The prevalence of pre-existing H1N1pdm-specific sero-antibodies in the elderly population (>60 years old) was 7.8%. The younger group, aged 19 to 60 years, exhibited a significant increase in seropositivity for H1N1pdm after the pandemic (4.9% before pandemic and 18.9% after pandemic, p < 0.05). The prevalence of H1N1pdm specific MBCs before the pandemic in the elderly (>60 years) and younger populations (<60 years) was 38% (8/21) and 48% (20/42), respectively (p = 0.6). The IFN-γ⁺ T cell responses to the pandemic and seasonal viruses were significantly lower in the elder group than those in the younger group (<60 years) (p < 0.05).

CONCLUSIONS

Pre-existing serum antibodies and memory B cells against H1N1pdm were low in all age group, whereas diminished memory T cell responses to this virus were observed in the elderly population both before and after the pandemic.

Nitric oxide has contrasting age-dependent effects on the functionality of murine hematopoietic stem cells

Background

The success of hematopoietic stem cell (HSC) transplantation is dependent on the quality of the donor HSCs. Some sources of HSCs display reduced engraftment efficiency either because of inadequate number (e.g., fetal liver and cord blood), or age-related dysfunction (e.g. in older individuals). Therefore, use of pharmacological compounds to improve functionality of HSCs is a forefront research area in hematology.

Methods

Lineage negative (Lin⁻) cells isolated from murine bone marrow or sort-purified Lin⁻Sca-1⁺c-Kit⁺CD34⁻ (LSK-CD34⁻) were treated with a nitric oxide donor, sodium nitroprusside (SNP). The cells were subjected to various phenotypic and functional assays.

Results

We found that SNP treatment of Lin⁻ cells leads to an increase in the numbers of LSK-CD34⁺ cells in them. Using sort-purified LSK CD34⁻ HSCs, we show that this is related to acquisition of CD34 expression by LSK-CD34⁻ cells, rather than proliferation of LSK-CD34⁺ cells. Most importantly, this upregulated expression of CD34 had age-dependent contrasting effects on HSC functionality. Increased CD34 expression significantly improved the engraftment of juvenile HSCs (6–8 weeks); in sharp contrast, it reduced the engraftment of adult HSCs (10–12 weeks). The molecular mechanism behind this phenomenon involved nitric oxide (NO)-mediated differential induction of various transcription factors involved in commitment with regard to self-renewal in adult and juvenile HSCs, respectively. Preliminary experiments performed on cord blood-derived and mobilized peripheral blood-derived cells revealed that NO exerts age-dependent contrasting effects on human HSCs as well.

Conclusions

This study demonstrates novel age-dependent contrasting effects of NO on HSC functionality and suggests that HSC age may be an important parameter in screening of various compounds for their use in manipulation of HSCs.

Electronic supplementary material

The online version of this article (doi:10.1186/s13287-016-0433-x) contains supplementary material, which is available to authorized users.

TRPV1 deletion exacerbates hyperthermic seizures in an age-dependent manner in mice

Febrile seizures (FS) are the most common seizure disorder to affect children. Although there is mounting evidence to support that FS occur when children have fever-induced hyperventilation leading to respiratory alkalosis, the underlying mechanisms of hyperthermia-induced hyperventilation and links to FS remain poorly understood. As transient receptor potential vanilloid-1 (TRPV1) receptors are heat-sensitive, play an important role in adult thermoregulation and modulate respiratory chemoreceptors, we hypothesize that TRPV1 activation is important for hyperthermia-induced hyperventilation leading to respiratory alkalosis and decreased FS thresholds, and consequently, TRPV1 KO mice will be relatively protected from hyperthermic seizures. To test our hypothesis we subjected postnatal (P) day 8-20 TRPV1 KO and C57BL/6 control mice to heated dry air. Seizure threshold temperature, latency and the rate of rise of body temperature during hyperthermia were assessed. At ages where differences in seizure thresholds were identified, head-out plethysmography was used to assess breathing and the rate of expired CO₂ in response to hyperthermia, to determine if the changes in seizure thresholds were related to respiratory alkalosis. Paradoxically, we observed a pro-convulsant effect of TRPV1 deletion (∼4min decrease in seizure latency), and increased ventilation in response to hyperthermia in TRPV1 KO compared to control mice at P20. This pro-convulsant effect of TRPV1 absence was not associated with an increased rate of expired CO₂, however, these mice had a more rapid rise in body temperature following exposure to hyperthermia than controls, and the expected linear relationship between body weight and seizure latency was absent. Based on these findings, we conclude that deletion of the TRPV1 receptor prevents reduction in hyperthermic seizure susceptibility in older mouse pups, via a mechanism that is independent of hyperthermia-induced respiratory alkalosis, but possibly involves impaired development of thermoregulatory mechanisms, although at present the mechanism remain unknown.

Ornamentation, age, and survival of female striped plateau lizards, Sceloporus virgatus

Individuals with greater expression of secondary sexual traits are often older and have higher survivorship than individuals with lower expression; if so, assessment of such indicator traits may provide genetic and/or direct benefits to potential mates. I examined the relationship between ornament expression, age, and survival in the striped plateau lizard, Sceloporus virgatus, a species with female-specific ornamentation that honestly signals reproductive quality. I followed a group of females from 2008 to 2013, examined ornament color and size as females aged, and compared ornamentation of survivors versus non-survivors. In addition, I explored whether other (non-ornamental) phenotypic characters predicted survival. I found that peak ornament expression (both color and size) of individual females changed year to year but appeared to be a weak signal of age due to high among-female variation in ornament expression that occurred independent of age and a non-linear pattern of change for ornament color. However, both absolute and relative ornament size did increase significantly as an individual aged and therefore may provide some age-related information such as reproductive investment, which is expected to increase as residual reproductive value declines with age. Individual survival was unrelated to peak ornament expression and to other phenotypic variables measured, providing no support for the ornament as a viability indicator and suggesting that individual survival prospects are affected by stochastic and environmental factors.

Effect of the common functional FKBP5 variant (rs1360780) on the hypothalamic-pituitary-adrenal axis and peripheral blood gene expression

Regulation of hypothalamic-pituitary-adrenal (HPA) axis reactivity plays an important role in the development of stress-related psychiatric disorders. FK506 binding protein 5 (FKBP5) modulates HPA axis reactivity via glucocorticoid receptor (GR; NR3C1) sensitivity and signaling. The T allele of the single nucleotide polymorphism, FKBP5 rs1360780 (C/T), is associated with higher FKBP5 induction by glucocorticoids. In the present study, we performed the dexamethasone/corticotropin releasing hormone (DEX/CRH) test and quantitative real-time PCR analysis of peripheral blood mononuclear cell (PBMC) cDNA samples in 174 and 278 non-clinical individuals, respectively. We found increased suppression of the stress hormone (cortisol) response to the DEX/CRH test (P=0.0016) in aged (>50 years) individuals carrying the T allele compared with aged non-T allele carriers. T carriers showed significant age-related changes in GR and FKBP5 mRNA expression levels in PBMCs (P=0.0013 and P=0.00048, respectively). Our results indicate that FKBP5 rs1360780 regulates HPA axis reactivity and expression levels of GR and FKBP5 in PBMCs in an age-dependent manner. Because these phenotypes of aged T carriers are similar to endophenotypes of people with post-traumatic stress disorder, our findings may be useful for determining the molecular mechanisms, treatment, and preventive strategies for this disease.