The effect of long-term corticosterone treatment on blood cell differentials and function in laboratory and wild-caught amphibian models

Falso, Paul Gerald; Noble, Christopher A.; Díaz, J. Mataix; Hayes, Tyrone B.

doi:10.1016/j.ygcen.2015.01.003

Cited by 41 publications

(31 citation statements)

References 69 publications

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“…Regarding the whole blood phagocytosis assay by flow cytometry, the corticosterone TA on the last day increased Cell % but not MFI, indicating that the amount of yeast engulfed was not different, but the number of cells with this ability was influenced by changes in CORT. Previous studies also found increased phagocytic activity (oxidative burst activity) after implants with corticosterone capsules in Lithobates catesbeianus (Falso et al., ), immersion in corticosterone‐treated water in Xenopus laevis (Falso et al., ), and restraint challenge (8–12 hr) in R. marina (Graham et al., ). Additionally, exposure to stressors and treatment with glucocorticoids increase the number of circulating neutrophils (Davis et al., ), and promote the clearance of foreign antigens, toxins, microorganisms, and dead cells by facilitating opsonization, activating the scavenger systems and stimulating the phagocytic ability (Barber et al., ; Dhabhar, and McEwen, ; Franchimont, ; Spies, Strehl, van der Goes, Bijlsma, & Buttgereit, ).…”

Section: Discussionmentioning

confidence: 77%

“…Based in our results, the corticosterone TA is an efficient way to simulate hormonal changes associated with the acute stress response in R. icterica . Otherwise, alternative hormone treatments, such as corticosterone capsules (Falso et al., ), might be more efficient in simulating hormonal changes associated with the chronic stress response in toads (e.g., keeping CORT elevated for longer periods).…”

Section: Discussionmentioning

confidence: 99%

“…Administration started at 10:30 am, with 3 min interval between individuals. This administration period was selected because it corresponds to the lowest CORT values in the amphibians’ daily variation, as has been characterized for other species, including toads and salamanders (Falso, Noble, Diaz, & Hayes, ; Pancak, and Taylor, ; Zerani, & Gobetti, ). This allowed a higher amplitude of response to the exogenous corticosterone TA.…”

Section: Methodsmentioning

confidence: 99%

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Corticosterone transdermal application in toads (Rhinella icterica): Effects on cellular and humoral immunity and steroid plasma levels

Assis

Titon

Queiroz‐Hazarbassanov

et al. 2017

J Exp Zool Pt A

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Previous studies in a variety of vertebrates show stressed animals to exhibit acute increases in glucocorticoid levels, with consequences for immune modulation. Chronically elevated glucocorticoid levels are mostly associated with immunosuppression. However, there is still a paucity of knowledge regarding the amphibian physiological reaction to short- and long-term stress conditions, including glucocorticoid effects on the immune response. In order to better clarify the relationship between glucocorticoids and immune response, newly captured Brazilian toads (Rhinella icterica) (1 week in captivity) were subjected to a daily transdermal application (TA), of corticosterone or vehicle, for 30 consecutive days. Measures were made on the first day (acute stressor) and last day (chronic stressor), at timepoints 1, 6, and 12 hr post TA. A number of variables were analyzed: corticosterone plasma levels (CORT); neutrophil/lymphocyte ratio (N:L); testosterone plasma levels (T); innate immune response, as indicated by bacterial killing ability (BKA); and whole blood phagocytosis. The corticosterone TA only simulated hormonal changes associated with the acute stress response, even after 30 consecutive days of the treatment, with the increased CORT in response after corticosterone TA being evident only 1 hr postapplication and not thereafter. The general responses to corticosterone TA included increased CORT and N:L at first day of the treatment, and increased CORT and phagocytosis on the last day of the treatment. A decrease in T and BKA associated with the time in captivity was also evident, suggesting that captivity may be a chronic stressor for these toads.

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Section: Discussionmentioning

confidence: 77%

Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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Corticosterone transdermal application in toads (Rhinella icterica): Effects on cellular and humoral immunity and steroid plasma levels

Assis

Titon

Queiroz‐Hazarbassanov

et al. 2017

J Exp Zool Pt A

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“…Several cellular and humoral immunosuppressive effects in response to stressors have been described in many vertebrate groups (Martin, ; Sapolsky et al., ). Previous studies have shown that the phagocytic activity (chemiluminescence measures) of blood neutrophils and macrophages in anurans respond in contrasting ways to long‐term stress conditions (Albert, Drouillard, Haffner, & Dixon, ; Dohm et al., ; Falso et al., ; Gilbertson, Haffner, Drouillar, Albert, & Dixon, ; Graham et al., ). Although plasma CORT levels increased in response to stressors, and macrophage phagocytosis may be directly modulated by GCs (Belayat et al., ; Barriga, Martín, Ortega, & Rodriguez, ), we found no correlation between PP and PE of peritoneal cells (macrophages and neutrophils) with plasma CORT levels in R. schneideri .…”

Section: Discussionmentioning

confidence: 99%

Captivity effects on immune response and steroid plasma levels of a Brazilian toad (Rhinella schneideri)

et al. 2017

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Stressors can increase plasma glucocorticoid (GC) levels and decrease plasma androgen levels in different species of vertebrates. GCs can have immune-enhancing or immunosuppressive effects, which are dependent upon stress duration and intensity. The worldwide decline in amphibian populations is strongly linked to an array of different stressors. The impacts of stress on GCs, androgens, and the immune response are important to clarify and should lead to the better development of conservation strategies. The present study in adult male toads of Rhinella schneideri investigated the effects of captivity (7, 30, and 60 days) on plasma corticosterone (CORT) and plasma testosterone (T), as well as innate immune responses, specifically humoral and cell mediated responses, as indicated by bacterial killing ability (BKA) and phagocytosis by peritoneal cells, respectively. Captivity increased CORT threefold and decreased T versus controls. CORT maintained a threefold elevation throughout the captivity period, while body mass and T gradually decreased with time in captivity. BKA was lower at day 30, versus days 7 and 60, while peritoneal cell phagocytic efficiency decreased after day 30, remaining low at day 60. Moreover, phagocytosis efficiency was positively associated with T and body condition, suggesting that the effects of chronic stress on reproductive potential and immune response might be associated with the state of energetic reserves.

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“…First, animals were killed via overdose of lidocaine ointment 5% applied on the dorsum and venter of the individuals. Then, blood samples were collected by cardiac puncture (Falso et al, 2015) using 26-gauge insulin needles and heparinized capillary tubes. One drop of the blood was used to make a standard smear on a microscope slide.…”

Section: Methodsmentioning

confidence: 99%

Leukocyte profiles of two neotropical anuran species affected by anthropogenic habitat alteration

Neto

Nowakowski

Silva

et al. 2020

Animal Conservation

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Many amphibian species are vulnerable to environmental changes, especially in the tropics where presumably a large number of species have evolved narrow niches. Rapid environmental changes, such as deforestation, may promote stress responses in anurans that could affect population viability. The stress response in vertebrates is highly conserved, often involving the liberation of glucocorticoids hormones and the recruitment of immune competent cells. The objective of this work was to evaluate leukocyte profiles among individuals of two neotropical anuran species affected by anthropogenic habitat alteration. We took blood samples from adult individuals of Physalaemus cuvieri and Scinax x-signatus in natural and converted habitats in NE Brazil. We analyzed differential leukocyte counts, where increases in neutrophils and decreases in lymphocytes are indicative of a stress response. Specimens of S. x-signatus captured in highly altered habitats presented a higher neutrophil:lymphocyte (N: L) ratios than individuals from natural habitats. In contrast, P. cuvieri individuals exhibited no difference in N:L ratios between habitat types. These results suggest that the immune response depends on the species and the level of habitat alteration. Although S. x-signatus can be considered a generalist species, individuals from this species exhibited increased stress response associated with habitat alteration. The lack of a strong stress response of P. cuvieri, may suggest that this species is more tolerant of habitat alteration or that those individuals have acclimated to anthropogenic stressors more rapidly than S. x-signatus. These variable responses of immune function in highly altered habitats suggest avenues for future experimental work that examines responses to multiple stressors, including disease, which could scale to population trends in altered habitats.

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The effect of long-term corticosterone treatment on blood cell differentials and function in laboratory and wild-caught amphibian models

Cited by 41 publications

References 69 publications

Corticosterone transdermal application in toads (Rhinella icterica): Effects on cellular and humoral immunity and steroid plasma levels

Corticosterone transdermal application in toads (Rhinella icterica): Effects on cellular and humoral immunity and steroid plasma levels

Captivity effects on immune response and steroid plasma levels of a Brazilian toad (Rhinella schneideri)

Leukocyte profiles of two neotropical anuran species affected by anthropogenic habitat alteration

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