Corticosteroid-binding globulin levels in North American sciurids: implications for the flying squirrel stress axis

2018 ◽  
Vol 96 (10) ◽  
pp. 1090-1096 ◽  
Author(s):  
Lanna M. Desantis ◽  
Jeff Bowman ◽  
Erin Faught ◽  
Rudy Boonstra ◽  
Mathilakath M. Vijayan ◽  
...  
Keyword(s):  
New World ◽  
Stress Axis ◽  
Glaucomys Sabrinus ◽  
Evolutionary Time ◽  
Glaucomys Volans ◽  
Flying Squirrels ◽  
Total Cortisol ◽  
Corticosteroid Binding Globulin ◽  
Tree Squirrels ◽  
Cortisol Levels

Corticosteroid-binding globulin (CBG) helps to regulate tissue bioavailability of circulating glucocorticoids (GCs), and in most vertebrates, ≥80%–90% of GCs bind to this protein. New World flying squirrels have higher plasma total cortisol levels (the primary corticosteroid in sciurids) than most vertebrates. Recent research suggests that flying squirrels have either low amounts of CBG or CBG molecules that have a low binding affinity for cortisol, as this taxon appears to exhibit very low proportions of cortisol bound to CBG. To test whether CBG levels have been adjusted over evolutionary time, we assessed the levels of this protein in the plasma of northern (Glaucomys sabrinus (Shaw, 1801)) and southern (Glaucomys volans (Linnaeus, 1758)) flying squirrels using immunoblotting, and compared the relative levels among three phylogenetically related species of sciurids. We also compared the pattern of CBG levels with cortisol levels for the same individuals. Flying squirrels had higher cortisol levels than the other species, but similar levels of CBG to their closest relatives (tree squirrels). We conclude that CBG levels in flying squirrels have not been adjusted over evolutionary time, and thus, the uncoupling of CBG levels from cortisol concentrations may represent an evolutionary modification in the lineage leading to New World flying squirrels.

scholarly journals Responses of New World flying squirrels to the acute stress of capture and handling

2015 ◽  
Vol 97 (1) ◽  
pp. 80-88 ◽  
Author(s):  
Lanna M. Desantis ◽  
Jeff Bowman ◽  
Candace V. Lahoda ◽  
Rudy Boonstra ◽  
Gary Burness
Keyword(s):  
Stress Response ◽  
New World ◽  
Binding Capacity ◽  
Biologically Active ◽  
Stress Axis ◽  
Neutrophil Lymphocyte Ratio ◽  
Flying Squirrels ◽  
Physiological Variables ◽  
Total Cortisol ◽  
Cortisol Levels

Abstract Northern ( Glaucomys sabrinus ) and southern ( G. volans ) flying squirrels have glucocorticoid (GC; stress hormone) levels higher than most vertebrates but virtually no binding capacity for these GCs via the carrier protein, corticosteroid-binding globulin. Thus, their total GCs are essentially all free and biologically active. However, the GC estimates come from blood samples taken after squirrels had been in live traps, and thus in a stress-induced state. Obtaining baseline values for physiological variables is valuable for assessing the response of vertebrates to stressors in their environment. We compared baseline plasma total cortisol levels (within 3min of capture) to stress-induced levels (after 30min of trap restraint) in both flying squirrel species. We recorded baseline cortisol levels that were some of the highest ever reported for mammals, indicating their stress axes operate at a higher set point than most other species. As part of the stress response, we also measured 4 indices in addition to cortisol. Total cortisol and free fatty acids increased in both species, as predicted. In contrast with our predictions, blood glucose and neutrophil/lymphocyte ratio showed no overall change, and hematocrit decreased significantly. New World flying squirrels therefore appear to have a stress response that differs from many other mammals. The selective forces driving the physiology of these animals remain elusive, but this lineage may provide an interesting comparative system for the study of stress axis function and its evolution among vertebrates.

scholarly journals The effect of social stress on adrenal axis activity in horses: the importance of monitoring corticosteroid-binding globulin capacity

1998 ◽  
Vol 157 (3) ◽  
pp. 425-432 ◽  
Author(s):  
SL Alexander ◽  
CH Irvine
Keyword(s):  
Social Stress ◽  
Plasma Cortisol ◽  
Binding Capacity ◽  
Plasma Concentrations ◽  
Social Instability ◽  
Total Cortisol ◽  
Adrenal Axis ◽  
Free Cortisol ◽  
Corticosteroid Binding Globulin ◽  
Cortisol Levels

Plasma cortisol is largely bound to corticosteroid-binding globulin (CBG), which regulates its bioavailability by restricting exit from capillaries. Levels of CBG may be altered by several factors including stress and this can influence the amount of cortisol reaching cells. This study investigated the effect of social instability on plasma concentrations of CBG, total and free (not protein bound) cortisol in horses. Horses new to our research herd ('newcomers') were confined in a small yard with four dominant resident horses for 3-4 h daily for 3-4 (n = 5) or 9-14 (n = 3) days. Jugular blood was collected in the mornings from newcomers before the period of stress began ('pre-stress'), and then before each day's stress. Residents were bled before stress on the first and thirteenth day. Residents always behaved aggressively towards newcomers. By the end of the stress period, all newcomers were subordinate to residents. In newcomers (n = 8) after 3-4 days of social stress, CBG binding capacity had fallen (P = 0.0025), while free cortisol concentrations had risen (P = 0.0016) from pre-stress values. In contrast, total cortisol did not change. In residents, CBG had decreased slightly but significantly (P = 0.0162) after 12 days of stress. Residents and newcomers did not differ in pre-stress CBG binding capacity, total or free cortisol concentrations. However, by the second week of stress, CBG binding capacity was lower (P = 0.015) and free cortisol higher (P = 0.030) in newcomers (n = 3) than in residents. Total cortisol did not differ between the groups. In conclusion social stress clearly affected the adrenal axis of subordinate newcomer horses, lowering the binding capacity of CBG and raising free cortisol concentrations. However, no effect of stress could be detected when only total cortisol was measured. Therefore, to assess adrenal axis status accurately in horses, it is essential to monitor the binding capacity of CBG and free cortisol concentrations in addition to total cortisol levels.

Northern range boundary dynamics of southern flying squirrels: evidence of an energetic bottleneck

2005 ◽  
Vol 83 (11) ◽  
pp. 1486-1494 ◽  
Author(s):  
Jeff Bowman ◽  
Gillian L Holloway ◽  
Jay R Malcolm ◽  
Kevin R Middel ◽  
Paul J Wilson
Keyword(s):  
Large Scale ◽  
Glaucomys Sabrinus ◽  
Glaucomys Volans ◽  
Cold Temperatures ◽  
Flying Squirrels ◽  
Rate Of Spread ◽  
Population Crash ◽  
Recent Climate ◽  
Large Scale Survey ◽  
Boundary Dynamics

We undertook a large-scale survey of the distribution of northern, Glaucomys sabrinus (Shaw, 1801), and southern, Glaucomys volans (L., 1758), flying squirrels in Ontario, Canada. Livetrapping was conducted along a north–south transect spanning about 500 km, from 42.5°N to 47.2°N. During 2002–2004, we conducted 42 971 trap-nights at 26 sites and captured 232 northern and 538 southern flying squirrels. During 2002 and 2003, southern flying squirrels occurred >200 km farther north than we expected. However, the range of this species appeared to contract to the south by about 240 km after the winter of 2004. Weather and food data suggested that cold temperatures during January and February 2004 combined with a failed mast crop in the autumn of 2003 resulted in an energetic bottleneck and subsequent population crash. We speculate that prior to 2004 southern flying squirrels had expanded their geographic range in response to recent climate warming. In particular, the nine winters between 1994 and 2004 were relatively warm. By measuring the range expansion over this warm interval, we were able to estimate a rate of spread of 22 km per year, and a diffusion coefficient of 6.9 × 107 m2 per generation.

Modeling impacts of landscape connectivity on dispersal movements of northern flying squirrels (Glaucomys sabrinus griseifrons)

2019 ◽  
Vol 394 ◽  
pp. 44-52 ◽  
Author(s):  
Stephanie E. Trapp ◽  
Casey C. Day ◽  
Elizabeth A. Flaherty ◽  
Patrick A. Zollner ◽  
Winston P. Smith
Keyword(s):  
Landscape Connectivity ◽  
Glaucomys Sabrinus ◽  
Flying Squirrels ◽  
Northern Flying Squirrels

scholarly journals Comparison of the hypothalamic–pituitary–adrenal axis susceptibility upon single-dose i.m. depot versus long-acting i.v. triamcinolone acetonide therapy: a direct pharmacokinetic correlation

2006 ◽  
Vol 191 (2) ◽  
pp. 491-496 ◽  
Author(s):  
Getu Abraham ◽  
Fioralba Demiraj ◽  
Fritz Rupert Ungemach
Keyword(s):  
Triamcinolone Acetonide ◽  
Plasma Concentrations ◽  
Stress Axis ◽  
Dihydrogen Phosphate ◽  
Maximum Plasma ◽  
Acth Challenge ◽  
Cortisol Responses ◽  
Baseline Values ◽  
Cortisol Levels ◽  
Long Acting

The effects of single injections of glucocorticoid (GC) depot suspension and of long-acting GC were studied in conscious dogs. Both the depot suspension GC triamcinolone-16,17-α-acetonide (TAA) and the long-acting triamcinolone acetonide-21-dihydrogen phosphate (TAA-DHP) decreased basal and ACTH-stimulated cortisol levels and in a specific time-dependent way. Before treatment, all dogs had normal basal and peak cortisol responses to ACTH challenge (13–15 and > 120 nmol/l at 1 h respectively). Intravenous TAA-DHP reduced cortisol levels for 12 h, i.m. TAA reduced cortisol levels as of 1.5 h and the effect lasted for at least 4 weeks. Both treatments blunted the peak response to ACTH. ACTH elevated cortisol levels to or above baseline values within 10 days following TAA-DHP treatment, but the TAA treatment suppressed an ACTH response for at least 4 weeks. Kinetic analysis of both the preparations demonstrated rapid absorption (tmax, 0.6–1.5 h) and low maximum plasma concentrations (peak Cmax, 2.99–5.51 nmol/l) of the steroids; indeed, the terminal half-life of TAA-DHP (13.9 ± 1.3 h) was very much shorter than that of TAA (125.9 ± 15.8 h). In addition, the mean residence time differed very much (11 vs 160 h for TAA-DHP and TAA respectively), in line with a delayed elimination of the depot compared with the long-acting formulation. Application of these TAA formulations needs careful evaluation for their surprisingly different effects on endocrine stress axis activity.

Photoperiod synchronizes reproduction and growth in the southern flying squirrel,Glaucomys volans

1990 ◽  
Vol 68 (1) ◽  
pp. 134-139 ◽  
Author(s):  
Theresa M. Lee ◽  
Irving Zucker
Keyword(s):  
Body Weight ◽  
Reproductive Condition ◽  
Glaucomys Volans ◽  
Flying Squirrel ◽  
Seasonal Rhythms ◽  
Flying Squirrels ◽  
Body Weights ◽  
Natural Photoperiod ◽  
Ad Libitum ◽  
Southern Flying Squirrel

Southern flying squirrels were housed in a simulated natural photoperiod for 40°N latitude and held at a constant temperature of 23 °C with food and water provided ad libitum. Body weight and reproductive condition were monitored weekly for 2 years. Males were in reproductive condition between January and mid-August and females were in estrus from late February to mid-April and again from mid-June until early August. Young were conceived during both estrous periods and several squirrels produced two litters in the same year. Minimum body weights were recorded in adults in mid-October each year. Pups born in the spring grew more rapidly than those from summer litters, and reached puberty at 2.5 months as compared with 6–8 months of age for the summer litters. Several seasonal rhythms appear to be controlled by photoperiod in this species.

Differences in trapping mortality rates of northern flying squirrels

1993 ◽  
Vol 71 (3) ◽  
pp. 660-663 ◽  
Author(s):  
Daniel K. Rosenberg ◽  
Robert G. Anthony
Keyword(s):  
Mortality Rates ◽  
Differential Mortality ◽  
Glaucomys Sabrinus ◽  
Adult Males ◽  
Extrinsic Factors ◽  
Age Cohorts ◽  
Flying Squirrels ◽  
Northern Flying Squirrel ◽  
Northern Flying Squirrels ◽  
Juvenile Males

We described trapping mortality rates of northern flying squirrel (Glaucomys sabrinus) populations in western Oregon, U.S.A., and evaluated the effects of sex, age, body mass, and number of times an individual was recaptured on these rates. Although the overall trapping mortality rates were relatively low (7%) during 16–21 day trapping sessions, we observed differential mortality rates among the sex and age cohorts. The order of mortality rates was: juvenile females (32.3%) > juvenile males (11.1%) > adult females (5.1%) = adult males (4.1%). Overall trapping mortality rates were not affected by the number of times an individual was captured. We hypothesize that the differences we found were due to extrinsic factors (weather-related) acting on differential behavioral responses to trapping and thresholds of stress an animal can tolerate.

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