scholarly journals Control of the Hypothalamo-Pituitary-Adrenal Axis in the Neonatal Period: Adrenocorticotropin and Corticosterone Stress Responses Dissociate in Vasopressin-Deficient Brattleboro Rats

Endocrinology ◽  
2008 ◽  
Vol 149 (5) ◽  
pp. 2576-2583 ◽  
Author(s):  
Dóra Zelena ◽  
Ágnes Domokos ◽  
István Barna ◽  
Zsuzsa Mergl ◽  
József Haller ◽  
...  

In adulthood the hypothalamo-pituitary-adrenal axis is controlled by both CRH and arginine vasopressin (AVP). However, in neonates CRH secretion is very low, whereas AVP secretion is fully functional. This suggests that the role of AVP is more pronounced in young than in adult rats. We investigated the role of AVP by studying stress responses in 5, 10, and 20-d-old AVP-deficient Brattleboro rats. Two different stressors were applied: 24-h maternal separation and Hypnorm Grove Oxford UK injections. In heterozygous controls (that do express AVP), both stressors increased plasma ACTH and corticosterone. The ACTH stress response disappeared in AVP-deficient rats, demonstrating that during the perinatal period, the secretion of this hormone is controlled by AVP. Surprisingly, corticosterone responses remained intact in AVP-deficient rats. Similar findings were obtained after 1-, 4-, 12-, and 24-h long maternal separations. Thus, preserved corticosterone stress responses were not explained by changes in the timing of ACTH secretion. In vitro experiments suggested that the dissociation of ACTH and corticosterone stress responses can only be partly explained by higher ACTH responsiveness of the adrenal cortex in AVP-deficient rats. Together, our results show that in neonatal periods, AVP is crucial for the expression of ACTH stress responses, but neither AVP nor ACTH is necessary for the induction of corticosterone stress responses. Discrepant ACTH and corticosterone stress responses may reflect compensatory mechanisms activated by AVP deficiency, but disparate findings suggest that they rather depict a neonate-specific mechanism of hypothalamo-pituitary-adrenal-axis control.

2003 ◽  
Vol 76 (3) ◽  
pp. 413-420 ◽  
Author(s):  
L. V. Osadchuk ◽  
B. O. Braastad ◽  
A. L. Hovland ◽  
M. Bakken

AbstractMan-animal relationships are involved in the process of fox domestication. Handling being an important part of man-animal contacts, causes stress responses in farm-bred blue foxes. The purpose of this study was to determine how prenatal stress induced by handling pregnant vixens influences certain morphometric and hormonal parameters of adrenocortical and gonadal function in the prepubertal offspring. Blue fox females were subjected to daily handling sessions, each of 1 min, in the last trimester of pregnancy (term = 52 days). Plasma concentrations of ACTH, cortisol, progesterone, oestradiol and testosterone, as well as the in vitro adrenal and gonadal production of steroids were measured by radio-immunoassay in control (C, no. = 56) and prenatally stressed (PS, no. = 56) blue fox cubs of both sexes at the age of 6 to 7 months. Prenatal stress decreased plasma concentration of cortisol (C: 31·0 (s.e. 4·3) v. PS: 22·7(s.e. 1·6) ng/ml, P < 0·05) as well as progesterone (C: 1·00(s.e. 0·10) v. PS: 0·65(s.e. 0·05) ng/ml, P < 0·05) in female cubs. Prenatal stress did not cause any changes in adrenal or gonadal weights, plasma concentrations of testosterone or oestradiol, or in vitro adrenal or gonadal steroid production, in either sex. It is concluded that persistent handling of pregnant blue foxes did not affect the prepubertal development of the reproductive system but resulted in disregulation in the hypothalamic-pituitary-adrenal axis in the female offspring.


Peptides ◽  
1998 ◽  
Vol 19 (5) ◽  
pp. 949-968 ◽  
Author(s):  
Gastone G. Nussdorfer ◽  
Ludwik K. Malendowicz

2003 ◽  
Vol 285 (5) ◽  
pp. E1110-E1117 ◽  
Author(s):  
D. Zelena ◽  
Z. Mergl ◽  
A. Földes ◽  
K. J. Kovács ◽  
Z. Tóth ◽  
...  

The role of hypothalamic structures in the regulation of chronic stress responses was studied by lesioning the mediobasal hypothalamus or the paraventricular nucleus of hypothalamus (PVH). Rats were acutely (60 min) and/or repeatedly (for 7 days) restrained. In controls, a single restraint elevated the plasma adrenocorticotropin (ACTH), corticosterone, and prolactin levels. Repeated restraint produced all signs of chronic stress, including decreased body and thymus weights, increased adrenal weight, basal corticosterone levels, and proopiomelanocortin (POMC) mRNA expression in the anterior pituitary. Some adaptation to repeated restraint of the ACTH response, but not of other hormonal responses, was seen. Lesioning of the mediobasal hypothalamus abolished the hormonal response and POMC mRNA activation to acute and/or repeated restraint, suggesting that the hypothalamo-pituitary-adrenal axis activation during repeated restraint is centrally driven. PVH lesion inhibited the ACTH and corticosterone rise to the first restraint by ∼50%. In repeatedly restrained rats with PVH lesion, the ACTH response to the last restraint was reduced almost to basal control levels, and the elevation of POMC mRNA level was prevented. PVH seems to be important for the repeated restraint-induced ACTH and POMC mRNA stimulation, but it appears to partially mediate other restraint-induced hormonal changes.


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