Pituitary-Adrenal Response in Neonatal Rats*

Guillet, Ronnie; Saffran, Murray; Michaelson, Sol M.

doi:10.1210/endo-106-3-991

Cited by 87 publications

(36 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…The vulnerability may be related to the neonate's immature metabolic and hormonal response to sepsis. 93,94 The HPA response is normally hyporesponsive between postnatal days 4-14 (stress-hyporesponsive period). During this period, LPS significantly decreased CRH gene expression in the PVN, contrasting the increases in Fos expression as well as in ACTH and cortisol.…”

Section: Modifying Factors: Nutritional Status Sex and Agementioning

confidence: 99%

Review: Endotoxin and the hypothalamo-pituitary-adrenal (HPA) axis

Beishuizen

Thijs

2003

Journal of Endotoxin Research

View full text Add to dashboard Cite

Endotoxin is considered to be a systemic (immunological) stressor eliciting a prolonged activation of the hypothalamo-pituitary-adrenal (HPA) axis. The HPA-axis response after an endotoxin challenge is mainly due to released cytokines (IL-1, IL-6 and TNF-a) from stimulated peripheral immune cells, which in turn stimulate different levels of the HPA axis. Controversy exists regarding the main locus of action of endotoxin on glucocorticoid secretion, since the effect of endotoxin on this neuro-endocrine axis has been observed in intact animals and after ablation of the hypothalamus; however, a lack of LPS effect has been described at both pituitary and adrenocortical levels. The resulting increase in adrenal glucocorticoids has well-documented inhibitory effects on the inflammatory process and on inflammatory cytokine release. Therefore, immune activation of the adrenal gland by endotoxin is thought to occur by cytokine stimulation of corticosteroidreleasing hormone (CRH) production in the median eminence of the hypothalamus, which, in turn stimulates the secretion of ACTH from the pituitary. Acute administration of endotoxin stimulates ACTH and cortisol secretion and the release of CRH and vasopressin (AVP) in the hypophysial portal blood. During repeated endotoxemia, tolerance of both immune and HPA function develops, with a crucial role for glucocorticoids in the modulation of the HPA axis. A single exposure to a high dose of LPS can induce a long-lasting state of tolerance to a second exposure of LPS, affecting the response of plasma TNF-a and HPA hormones. Although there are gender differences in the HPA response to endotoxin and IL-1, these responses are enhanced by castration and attenuated by androgen and estrogen replacement. Estrogens attenuate the endotoxin-induced stimulation of IL-6, TNF-a and IL-1ra release and subsequent activation in postmenopausal women. There appears to be a temporal and functional relation between the HPA-axis response to endotoxin and nitric oxide formation in the neuro-endocrine hypothalamus, suggesting a stimulatory role for nitric oxide in modulating the HPA response to immune challenges. demonstrate higher plasma levels of IL-1 and TNF-a. Elevation of plasma glucocorticoids results in suppression of cytokines such as IL-1, IL-6, and TNF-a and in up-regulation of other cytokines, such as IL-4 and IL-10, and cytokine receptors. Thus, by regulation of cytokine production and action, the HPA axis contributes to modulation of the response to inflammation/infection. In addition, the role of HPA activation has been suggested to be a negative feedback system provided by the immunosuppressive activity of glucocorticoids, limiting inflammatory responses and preventing the immune system from over-reacting and causing tissue damage or autoimmunity.As early as 1957, Wexler et al. suggested that LPS could induce ACTH release since they found a depletion of ascorbic acid and cholesterol in the adrenal glands. 10 Moreover, LPS was not able to cause these changes in hypophysectomized rats. ...

show abstract

Section: Modifying Factors: Nutritional Status Sex and Agementioning

confidence: 99%

Review: Endotoxin and the hypothalamo-pituitary-adrenal (HPA) axis

Beishuizen

Thijs

2003

Journal of Endotoxin Research

View full text Add to dashboard Cite

show abstract

“…In adult rats, it is well established that in phase daily variation of the adrenal responsiveness to ACTH amplifies the CB rhythm [6]. In neonatal animals, numerous studies have pointed to a limited adrenal response to ACTH [7, 8, 9, 10, 11]. However, the diurnal variation of adrenal responsiveness to ACTH has not been addressed.…”

Section: Introductionmentioning

confidence: 99%

Ontogenetic Diurnal Variation of Adrenal Responsiveness to ACTH and Stress in Rats

Leal¹,

Carvalho²,

Moreira³

1999

Horm Res Paediatr

View full text Add to dashboard Cite

We performed studies in 8-, 16-, 24-, 30 and 35-day-old Wistar rats at 8.00 h (AM) and 20.00 h (PM) to investigate the relationship between the diurnal variations of basal plasma corticosterone (compound B, CB) and its responses to ACTH and ether stress during the postnatal period. Basal plasma CB levels increased at PM from 8 to 35 days of age and an AM-PM difference was observed at 16 days. Although an AM-PM difference in CB responsiveness to ACTH was detected only at 24 and 35 days, ACTH induced an increasingly higher CB response at PM than at AM from 8 to 35 days. A stress-induced CB response was observed starting at 8 days of age and presented an age-dependent increase; however, no AM-PM difference was observed at any age. The stress-induced CB levels were higher than ACTH-induced CB values at all ages tested except at PM in 8-day old rats. These data demonstrate that the basal CB levels and adrenal sensitivity to ACTH rise during the evening as a function of neonatal development.

show abstract

“…Any residual manifestation of a stress-hyporesponsive period (Guillet, Saffran, & Michaelson, 1980;Witek-Janusek, 1988) could, for instance, intensify sickness behavior caused by a reduction in the glucocorticoid negative feedback effect on cytokine production (Chrousos, 1995). Low ability of juveniles' lymphocytes to secrete the Mn<l> costimulant interferon-gamma (Adkins et aI., 1993) could attenuate sickness behavior.…”

mentioning

confidence: 99%

Lipopolysaccharide-Induced Immunostimulation Produces A Dose- and Time-Dependent Decrease in General Activity and Weight Gain in Preweanling Rats

et al. 2003

View full text Add to dashboard Cite

The immunostimulant lipopolysaccharide (LPS) produces numerous physiological and behavioral effects in adult rodents. The present study examined the effects of this endotoxin on activity levels and weight gain in 20-day-old preweanling rats. Experiment 1 demonstrated that 400 ~g/kg of LPS produced a significant decline in locomotor activity 1 hr postinjection, and both 200 ~g/kg and 400 ~g/kg significantly suppressed weight gain over the first 24 hr posttreatment. The effect on weight gain dissipated by 48 hr following LPS administration. Experiment 2 replicated the effects of 400 ~g/kg LPS on activity at 1 hr and on weight gain, and also assessed its effects upon activity level 24 hr following administration. Despite the significant decline in weight gain over the initial postinjection day, LPS animals' activity level was normal 24 hr after injection. These results indicate that the endotoxin LPS produces significant but transient decreases in both locomotor activity and weight gain in preweanling rats. The relationship of these findings to other issues involving physiology and sickness behavior is discussed.

show abstract

Pituitary-Adrenal Response in Neonatal Rats*

Cited by 87 publications

References 0 publications

Review: Endotoxin and the hypothalamo-pituitary-adrenal (HPA) axis

Review: Endotoxin and the hypothalamo-pituitary-adrenal (HPA) axis

Ontogenetic Diurnal Variation of Adrenal Responsiveness to ACTH and Stress in Rats

Lipopolysaccharide-Induced Immunostimulation Produces A Dose- and Time-Dependent Decrease in General Activity and Weight Gain in Preweanling Rats

Contact Info

Product

Resources

About