Age and Gender Influence Basal and Stress-Modulated Hypothalamic-Pituitary-Thyroidal Function in Fischer 344/N Rats

Cizza, Giovanni; Brady, Linda S.; Esclapes, Maribel; Blackman, Marc R.; Gold, Philip W.; Chrousos, George P.

doi:10.1159/000127150

Cited by 40 publications

(36 citation statements)

References 21 publications

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“…In line with these results, there are other studies that show this plant has decreasing effect on the levels of T3 and T4 (9,23). Further investigation indicated that basil leaf extract reduces serum concentrations of T4 (33). Another study found that Betel leaf extract in the lowest dose increases concentrations of T3 but increases concentration of T4 and decreases T3 concentration at higher doses (34).…”

Section: Discussionsupporting

confidence: 67%

“…However, there are other studies that show thyroid hormone levels decrease during chronic immobilization stress (7,30). Other studies also argue that chronic immobilization stress decreases plasma levels of TSH and hypothalamic TRH mRNA levels in young rats (32,33). In justifying the lack of effect of chronic immobilization stress on levels of hormones T3, T4 and TSH, adaptation of rats with this stress (13) may fail in changing the activity of thyroid gland during the implementation of this type of stress.…”

Section: Discussionmentioning

confidence: 99%

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The Effects of Acute and Chronic Immobilization Stress and Aloe vera Extract on Serum Levels of TSH, T3 and T4 in Male Rats

2015

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Background: Stress has different effects on the body and endocrine system. Objectives: The main aim of this study is to determine the effects of immobilization stress and Aloe vera extract on levels of TSH, T3 or T4 in male rats. Materials and Methods: In this experimental study, 90 male Wistar rats were randomly divided into 9 groups of control, receiving normal saline, receiving Aloe vera extract, acutely immobilized (8 h/day immobilization for 8 days), chronically immobilized (2 h/day immobilization for 21 days) acutely immobilized receiving Aloe vera extract, chronically immobilized receiving Aloe vera extract, acutely immobilized receiving normal saline and chronically immobilized receiving normal saline (n = 10). Blood samples were collected using cardiac puncture method and hormone levels were measured by electrochemiluminescence (ECL) method. Data were statistically analyzed and compared among groups using ANOVA. Results: Results showed that levels of T3 and T4 were significantly increased in rats enduring acute immobilization stress compared with animals in control group (P = 0.001). Serum T3 and T4 were significantly decreased in Aloe vera receiving rats compared with control group (P < 0.05 or P < 0.01, respectively). Level of T3 was significantly decreased in acutely immobilized rats receiving Aloe vera compared with control group (P = 0.001). Level of T3 and T4 levels were significantly decreased in chronically immobilized rats receiving Aloe vera compared with control group (P < 0.05). Conclusions:The findings show that acute immobilization enhances levels of T3, T4 and TSH and the use of Aloe vera extract can prevent this kind of increase.

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Section: Discussionsupporting

confidence: 67%

Section: Discussionmentioning

confidence: 99%

The Effects of Acute and Chronic Immobilization Stress and Aloe vera Extract on Serum Levels of TSH, T3 and T4 in Male Rats

2015

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“…Within s-variant females, dominant females had higher levels than subordinate animals. Thyroid hormones are reduced by hypercortisolism associated with chronic disease [75] as well as restraint stress [76] and food restriction [77,78], effects that may be mediated through a reduction in hypothalamic TRH expression. However, other data indicate this decrease induced by food restriction [47] and stress [48] may occur independent of changes in TRH expression.…”

Section: Discussionmentioning

confidence: 99%

Polymorphisms in the serotonin reuptake transporter gene modify the consequences of social status on metabolic health in female rhesus monkeys

Jarrell¹,

Hoffman²,

Kaplan³

et al. 2008

Physiology & Behavior

109

163

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Individuals vary substantially in their vulnerability to physical and psychosocial stressors. The causes of such variation in susceptibility to stress are poorly understood, but are thought to relate in part to genetic factors. The present study evaluated the extent to which polymorphisms in the gene encoding the serotonin reuptake transporter (5HTTLPR or SERT) modulated physiologic responses to the imposition of psychosocial stress (social reorganization and subordinate social status) in female rhesus monkeys. Forty females, drawn from the middle ranking genealogies of several large social groups, were reorganized into eight groups containing 5 monkeys each; four groups were comprised entirely of animals homogeneous for the long promoter variant in the SERT gene (l/l), while the other four groups had monkeys with at least one allele of the short promoter variant (l/s or s/s). Females were sequentially introduced into these new groups in random order and dominance ranks were established within several days. During the ensuing 6 weeks, dominant monkeys exhibited elevated rates of aggression while subordinates displayed high rates of submission. Notably, females with the s-variant SERT genotype, collapsed across social status positions, exhibited the highest overall rates of both aggression and submission. Although neither social status nor SERT genotype influenced morning cortisol concentrations, glucocorticoid negative feedback was reduced significantly in subordinate compared to dominant females irrespective of genotype. All animals lost weight and abdominal fat across the experiment. However, decreases were greatest in subordinates, regardless of genotype, and least in dominant females with the l/l genotype. Serum concentrations of insulin, glucose, and ghrelin decreased significantly during the group formation process, effects that were independent of genotype or social status. In contrast, social status and genotype interacted to influence changes in serum concentrations of leptin and triiodothyronine (T3), as dominant, l/l females had the highest levels while subordinate s-variant females had the lowest levels. The order in which a female was introduced to her group generally predicted her eventual social rank. However, rank was additionally predicted by pre-experimental T3 and abdominal fat values, but only in the l/l animals. While these findings must be replicated with a larger sample size, the data suggest that the s-variant SERT genotype confers increased vulnerability to the adverse effects of psychosocial stress associated with subordinate status while the l/l genotype benefits the most from the absence of stress conferred by dominant social status. These findings suggest that genetic factors modify the responses of monkeys to social subordination and perhaps other psychosocial stressors.

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“…For these reasons, differentiation between primary (or direct) immunotoxic effects and secondary indirect (or stress-related) effects in routine toxicity studies can be challenging Cizza et al 1996;Dominguez-Gerpe and Rey-Mendez 1998). Nevertheless, the morphology of thymus and spleen are an important part of the data set used for the weight-of-evidence approach for evaluating potential stress-related changes.…”

Section: Physiological Organization Of the Immune Systemmentioning

confidence: 99%

Interpreting Stress Responses during Routine Toxicity Studies

et al. 2013

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Stress often occurs during toxicity studies. The perception of sensory stimuli as stressful primarily results in catecholamine release and activation of the hypothalamic-pituitary-adrenal (HPA) axis to increase serum glucocorticoid concentrations. Downstream effects of these neuroendocrine signals may include decreased total body weights or body weight gain; food consumption and activity; altered organ weights (e.g., thymus, spleen, adrenal); lymphocyte depletion in thymus and spleen; altered circulating leukocyte counts (e.g., increased neutrophils with decreased lymphocytes and eosinophils); and altered reproductive functions. Typically, only some of these findings occur in a given study. Stress responses should be interpreted as secondary (indirect) rather than primary (direct) test article-related findings. Determining whether effects are the result of stress requires a weight-of-evidence approach. The evaluation and interpretation of routinely collected data (standard in-life, clinical pathology, and anatomic pathology endpoints) are appropriate and generally sufficient to assess whether or not changes are secondary to stress. The impact of possible stress-induced effects on data interpretation can partially be mitigated by toxicity study designs that use appropriate control groups (e.g., cohorts treated with vehicle and subjected to the same procedures as those dosed with test article), housing that minimizes isolation and offers environmental enrichment, and experimental procedures that minimize stress and sampling and analytical bias.This article is a comprehensive overview of the biological aspects of the stress response, beginning with a Summary (Section 1) and an Introduction (Section 2) that describes the historical and conventional methods used to characterize acute and chronic stress responses. These sections are followed by reviews of the primary systems and parameters that regulate and/or are influenced by stress, with an emphasis on parameters evaluated in toxicity studies:

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Age and Gender Influence Basal and Stress-Modulated Hypothalamic-Pituitary-Thyroidal Function in Fischer 344/N Rats

Cited by 40 publications

References 21 publications

The Effects of Acute and Chronic Immobilization Stress and Aloe vera Extract on Serum Levels of TSH, T3 and T4 in Male Rats

The Effects of Acute and Chronic Immobilization Stress and Aloe vera Extract on Serum Levels of TSH, T3 and T4 in Male Rats

Polymorphisms in the serotonin reuptake transporter gene modify the consequences of social status on metabolic health in female rhesus monkeys

Interpreting Stress Responses during Routine Toxicity Studies

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