Influence of Stressor Duration on Leukocyte and Hormonal Responses in Male Southeastern Five‐Lined Skinks (<i>Plestiodon inexpectatus</i>)

Seddon, Ryan J.

doi:10.1002/jez.1742

Cited by 29 publications

(31 citation statements)

References 78 publications

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“…The typical response to acute stress in this and a large variety of other species is a reduction in total leukocytes (Davis 2005;Noda et aJ. 2006;Buehler et aL 2008;Seddon and Klukowski 2012), and this is what we observed in uninfected house finches when stressed (a 30% decline in WBC abundance; fig. 3A).…”

Section: Discussionsupporting

confidence: 64%

Infection withMycoplasma gallisepticumBuffers the Effects of Acute Stress on Innate Immunity in House Finches

Fratto¹,

Ezenwa²,

Davis³

2014

Physiological and Biochemical Zoology

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When wild animals become infected, they still must cope with the rigors of daily life, and, thus, they still can be exposed to acute stressors. The suite of physiological responses to acute stress includes modifying the innate immune system, but infections can also cause similar changes. We examined the effects of an acute stressor (capture stress) on leukocyte abundance and bacteria-killing ability (BKA) in wild birds (house finches Haemorhous mexicanus) with and without a naturally occurring infection (Mycoplasma gallisepticum) to determine whether infection alters the typical immune response to stress. Birds were captured and bled within 3 min (baseline sample) and then held in paper bags for 2 h and bled again (stress sample). From blood smears made at both time points, we obtained estimates of total white blood cell (WBC) counts and relative numbers of each cell. We also measured BKA of plasma at both time points. In uninfected birds (n = 26), total WBC count decreased by 30% over time, while in infected birds (n = 9), it decreased by 6%. Relative numbers of heterophils did not change over time in uninfected birds but increased in infected birds. Combined with a reduction in lymphocyte numbers, this led to a threefold increase in heterophil-lymphocyte values in infected birds after the stressor, compared to a twofold increase in uninfected birds. There was a nonsignificant tendency for BKA to decline with stress in uninfected birds but not in diseased birds. Collectively, these results suggest that infections can buffer the negative effects of acute stress on innate immunity.

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Section: Discussionsupporting

confidence: 64%

Infection withMycoplasma gallisepticumBuffers the Effects of Acute Stress on Innate Immunity in House Finches

Fratto¹,

Ezenwa²,

Davis³

2014

Physiological and Biochemical Zoology

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“…These studies suggest that, although chronically elevated plasma CORT and/ or T appear to be immunosuppressive, this is not necessarily the case of acute CORT elevation (Martin 2009) and, furthermore, that T may interact with the effects of CORT. However, few studies of wild animals have investigated interactions between plasma CORT and innate immune performance during acute stress (Berger et al 2005;de Assis et al 2015;Graham et al 2012;Merrill et al 2012;Seddon and Klukowski 2012), and, to our knowledge, none has investigated the simultaneous responses of CORT, T, and innate immune performance in a wild vertebrate. Considering that plasma CORT and T change rapidly during the stress response, it is unclear which, if any, of these hormones is correlated with the changes in immune function during acute stress in wild animals.…”

Section: Introductionmentioning

confidence: 93%

Innate immunity and testosterone rapidly respond to acute stress, but is corticosterone at the helm?

et al. 2016

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When faced with a stressor, vertebrates can rapidly increase the secretion of glucocorticoids, which is thought to improve the chances of survival. Concurrent changes in other physiological systems, such as the reproductive endocrine or innate immune systems, have received less attention, particularly in wild vertebrates. It is often thought that glucocorticoids directly modulate immune performance during a stress response, but, in many species, androgens also rapidly respond to stress. However, to our knowledge, no study has simultaneously examined the interactions between the glucocorticoid, androgen, and innate immune responses to stress in a wild vertebrate. To address this issue, we tested the hypothesis that the change in plasma corticosterone (CORT) in response to the acute stress of capture and restraint is correlated with the concurrent changes in plasma testosterone (T) and innate immune performance (estimated by the capacity of plasma to agglutinate and lyse foreign cells) in the Abert's Towhee (Melozone aberti). Furthermore, to broaden the generality of the findings, we compared male and female towhees, as well as males from urban and non-urban populations. Acute stress increased plasma CORT, decreased plasma T in males, and decreased innate immune performance, but the increase in CORT during stress was not correlated with the corresponding decreases in either plasma T or innate immunity. By contrast, the plasma T stress response was positively correlated with the innate immune stress response. Collectively, our results challenge the proposition that the glucocorticoid stress response is correlated with the concurrent changes in plasma T, a key reproductive hormone, and innate immunity, as estimated by agglutination and lysis.

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“…The skinks that were used in this study were part of a larger study that investigated the effects of confinement stress on leukocyte counts and hormone concentrations (Seddon and Klukowski, 2012). This report focuses on the relationships among head coloration, plasma testosterone concentrations, and total leukocyte counts.…”

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confidence: 99%

Secondary sexual coloration is related to white blood cell counts and testosterone in male southeastern five-lined skinks (Plestiodon inexpectatus)

Seddon

2013

Amphib Reptilia

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The immunocompetence handicap hypothesis posits that secondary sexual colorafion can honestly signal male quality because elevated testosterone, which is necessary for the expression of the coloration, also handicaps males through immunosuppression. Thus only high quality males can express the showiest coloration in spite of immunosuppression. Here we report a test of the immunocompetence handicap hypothesis in southeastern five-lined skinks, Plestiodon inexpectatus, which exhibit a reddish-orange head coloration during the breeding season. We tested whether head coloration is related to circulating testosterone concentrations and reflects the status of a male's immune system, as measured by total leukocyte counts. As predicted, hue, saturation, and extent of head coloration were correlated with plasma testosterone, and the brightness of the head was negatively correlated with total circulating leukocytes. While results are consistent with the immunocompetence handicap hypothesis, additional studies that include experimental manipulations of testosterone levels and measure other aspects of immunity are warranted.

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Influence of Stressor Duration on Leukocyte and Hormonal Responses in Male Southeastern Five‐Lined Skinks (Plestiodon inexpectatus)

Cited by 29 publications

References 78 publications

Infection withMycoplasma gallisepticumBuffers the Effects of Acute Stress on Innate Immunity in House Finches

Infection withMycoplasma gallisepticumBuffers the Effects of Acute Stress on Innate Immunity in House Finches

Innate immunity and testosterone rapidly respond to acute stress, but is corticosterone at the helm?

Secondary sexual coloration is related to white blood cell counts and testosterone in male southeastern five-lined skinks (Plestiodon inexpectatus)

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