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Effects of acute restraint stress, prolonged captivity stress and transdermal corticosterone application on immunocompetence and plasma levels of corticosterone on the cururu Toad (Rhinella icterica).

de Assis VR, Titon SC, Barsotti AM, Titon B, Gomes FR - PLoS ONE (2015)

Bottom Line: Such bimodal effects have been associated with variation in duration and intensity of the stress response.Interestingly, long-term captivity did not mitigate the stress response, since the toads maintained 3-fold increased CORT even after 3 months under these conditions.Moreover, long-term captivity in the same condition increased total leukocyte count (TLC) and generated an even greater decrease in BKA, suggesting that consequences of the stress response can be aggravated by time in captivity.

View Article: PubMed Central - PubMed

Affiliation: Departamento de Fisiologia, Instituto de Biociências, Universidade de São Paulo, Rua do Matão, trav. 14, 101, 05508-900, São Paulo, SP, Brazil.

ABSTRACT
Glucocorticoid steroids modulate immunocompetence in complex ways with both immunoenhancing and immunosuppressive effects in vertebrates exposed to different stressors. Such bimodal effects have been associated with variation in duration and intensity of the stress response. Given that natural populations have been exposed to a multitude of stressors, a better understanding of the functional association between duration and intensity of the stress response, the resulting changes in glucocorticoid plasma levels and their impact on different aspects of immunocompetence emerges as a cornerstone for vertebrate conservation strategies. We investigated the effects of a restraint challenge (with and without movement restriction), long-term captivity, and transdermal corticosterone application on plasma levels of corticosterone (hereinafter referred to as CORT) and different parameters of innate immunocompetence in the male cururu toads (Rhinella icterica). We show that for R. icterica restraint for 24h proved to be a stressful condition, increasing CORT by 3-fold without consistent immunological changes. However, the application of a more intense stressor (restraint with movement restriction), for the same period, potentiated this response resulting in a 9-fold increase in CORT, associated with increase Neutrophil/Lymphocyte ratio (N:L) and a lower bacterial killing ability (BKA). Transdermal application of corticosterone efficiently mimics repeated acute stress response events, without changing the immune parameters even after 13 days of treatment. Interestingly, long-term captivity did not mitigate the stress response, since the toads maintained 3-fold increased CORT even after 3 months under these conditions. Moreover, long-term captivity in the same condition increased total leukocyte count (TLC) and generated an even greater decrease in BKA, suggesting that consequences of the stress response can be aggravated by time in captivity.

No MeSH data available.


Related in: MedlinePlus

Baseline and after restraint corticosterone plasma levels.Corticosterone plasma levels of toads (Rhinella icterica) under field conditions and after 24h of restraint challenge with and without movement restriction. Bars represent mean ± standard error with N in parentheses. *P ≤ 0.012; **P ≤ 0.001.
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pone.0121005.g005: Baseline and after restraint corticosterone plasma levels.Corticosterone plasma levels of toads (Rhinella icterica) under field conditions and after 24h of restraint challenge with and without movement restriction. Bars represent mean ± standard error with N in parentheses. *P ≤ 0.012; **P ≤ 0.001.

Mentions: Individuals kept in captivity within plastic containers for 24h (restraint without movement restriction) showed a mean decrease of 38% in TLC and 3-fold increase in CORT (Fig. 5), without changes in other measured parameters (Table 4). Otherwise, individuals maintained within moistened cloth bags for 24h (restraint with movement restriction), showed a mean decrease of 12% in BKA, a 4-fold increase in N:L ratio, and a 9-fold increase in CORT (Fig. 5), without changes in other measured parameters (Table 4).


Effects of acute restraint stress, prolonged captivity stress and transdermal corticosterone application on immunocompetence and plasma levels of corticosterone on the cururu Toad (Rhinella icterica).

de Assis VR, Titon SC, Barsotti AM, Titon B, Gomes FR - PLoS ONE (2015)

Baseline and after restraint corticosterone plasma levels.Corticosterone plasma levels of toads (Rhinella icterica) under field conditions and after 24h of restraint challenge with and without movement restriction. Bars represent mean ± standard error with N in parentheses. *P ≤ 0.012; **P ≤ 0.001.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4382218&req=5

pone.0121005.g005: Baseline and after restraint corticosterone plasma levels.Corticosterone plasma levels of toads (Rhinella icterica) under field conditions and after 24h of restraint challenge with and without movement restriction. Bars represent mean ± standard error with N in parentheses. *P ≤ 0.012; **P ≤ 0.001.
Mentions: Individuals kept in captivity within plastic containers for 24h (restraint without movement restriction) showed a mean decrease of 38% in TLC and 3-fold increase in CORT (Fig. 5), without changes in other measured parameters (Table 4). Otherwise, individuals maintained within moistened cloth bags for 24h (restraint with movement restriction), showed a mean decrease of 12% in BKA, a 4-fold increase in N:L ratio, and a 9-fold increase in CORT (Fig. 5), without changes in other measured parameters (Table 4).

Bottom Line: Such bimodal effects have been associated with variation in duration and intensity of the stress response.Interestingly, long-term captivity did not mitigate the stress response, since the toads maintained 3-fold increased CORT even after 3 months under these conditions.Moreover, long-term captivity in the same condition increased total leukocyte count (TLC) and generated an even greater decrease in BKA, suggesting that consequences of the stress response can be aggravated by time in captivity.

View Article: PubMed Central - PubMed

Affiliation: Departamento de Fisiologia, Instituto de Biociências, Universidade de São Paulo, Rua do Matão, trav. 14, 101, 05508-900, São Paulo, SP, Brazil.

ABSTRACT
Glucocorticoid steroids modulate immunocompetence in complex ways with both immunoenhancing and immunosuppressive effects in vertebrates exposed to different stressors. Such bimodal effects have been associated with variation in duration and intensity of the stress response. Given that natural populations have been exposed to a multitude of stressors, a better understanding of the functional association between duration and intensity of the stress response, the resulting changes in glucocorticoid plasma levels and their impact on different aspects of immunocompetence emerges as a cornerstone for vertebrate conservation strategies. We investigated the effects of a restraint challenge (with and without movement restriction), long-term captivity, and transdermal corticosterone application on plasma levels of corticosterone (hereinafter referred to as CORT) and different parameters of innate immunocompetence in the male cururu toads (Rhinella icterica). We show that for R. icterica restraint for 24h proved to be a stressful condition, increasing CORT by 3-fold without consistent immunological changes. However, the application of a more intense stressor (restraint with movement restriction), for the same period, potentiated this response resulting in a 9-fold increase in CORT, associated with increase Neutrophil/Lymphocyte ratio (N:L) and a lower bacterial killing ability (BKA). Transdermal application of corticosterone efficiently mimics repeated acute stress response events, without changing the immune parameters even after 13 days of treatment. Interestingly, long-term captivity did not mitigate the stress response, since the toads maintained 3-fold increased CORT even after 3 months under these conditions. Moreover, long-term captivity in the same condition increased total leukocyte count (TLC) and generated an even greater decrease in BKA, suggesting that consequences of the stress response can be aggravated by time in captivity.

No MeSH data available.


Related in: MedlinePlus