Hypothalamic-pituitary-adrenal axis up-regulation in rats submitted to pituitary stalk compression

Abstract

The present study investigated the hypothalamicpituitary-adrenal (HPA) axis activity in response to stress in adult male rats submitted to pituitary stalk compression (PSC) or sham operation. Animals received water or oral salt loading (2% NaCl) for one or eight days before the day of the experiment. On the 14th day post-surgery rats were killed under basal conditions or after 15 min immobilization stress. In the PSC group urine output increased significantly and plasma vasopressin (AVP) levels failed to respond to osmotic stimuli. Short-term salt load induced a significant increase in AVP levels in the sham-operated group. The PSC group presented higher adrenocorticotrophin (ACTH) and corticosterone levels compared with sham-operated rats, both in water intake and salt load conditions. Immobilization stress induced a similar increase in plasma ACTH and corticosterone concentrations in sham-operated and PSC groups under water intake. However, long-term salt load blunted the ACTH and corticosterone responses to immobilization stress in sham-operated rats. PSC rats submitted to short-and long-term salt loading presented no changes in ACTH and corticosterone levels after immobilization. Immobilization stress caused neither AVP responses nor plasma osmolality changes in sham and PSC groups. There was no difference in median eminence AVP content among all groups. In conclusion, the high ACTH and corticosterone levels found in PSC rats under water intake and salt loading conditions suggest an up-regulation of the HPA axis, with a preserved adaptive mechanism to chronic stress.

Endoplasmic reticulum stress induces apoptosis of arginine vasopressin neurons in central diabetes insipidus via PI3K/Akt pathway

“…Injury of the pituitary stalk could lead to imbalance of HNS and even cause severe hypothalamic dysfunction . Among these, central diabetes insipidus (CDI), characterized by polyuria, polydipsia, and low urine specific gravity, is a typical complication after surgery, trauma, or tumor around the hypothalamus …”

“…1,2 Among these, central diabetes insipidus (CDI), characterized by polyuria, polydipsia, and low urine specific gravity, is a typical complication after surgery, trauma, or tumor around the hypothalamus. 3,4 In this work, we used a pituitary stalk electrical lesion (PEL) model to induce CDI condition, by targeting pituitary stalk without interrupting the adenohypophysis and portal circulation based on previous studies. 3,5,6 Several former studies have reported a decreased number of arginine vasopressin (AVP) neurons in the hypothalamic nuclei and a production of apoptotic AVP neurons after hypophysectomy, but the underlying mechanism remains elusive.…”

“…3,4 In this work, we used a pituitary stalk electrical lesion (PEL) model to induce CDI condition, by targeting pituitary stalk without interrupting the adenohypophysis and portal circulation based on previous studies. 3,5,6 Several former studies have reported a decreased number of arginine vasopressin (AVP) neurons in the hypothalamic nuclei and a production of apoptotic AVP neurons after hypophysectomy, but the underlying mechanism remains elusive. 6,7 Meanwhile, numerous studies have verified the effect of endoplasmic reticulum (ER) stress on inducing cell apoptosis in other issues.…”

Prostaglandin mediates endotoxaemia‐induced hypophagia by activation of pro‐opiomelanocortin and corticotrophin‐releasing factor neurons in rats

“…Plasma ACTH and corticosterone levels were determined by specific radioimmunoassays after extraction with silicic acid and ethanol, respectively, as previously described (Elias et al 1997, 2004). The ACTH and corticosterone antisera were kindly provided by Dr Toshihiro Suda (Hirosaki University School of Medicine, Japan) and Dr Jose Gilberto Vieira (Federal University of Sao Paulo, Brazil), respectively.…”

Effects of early protein malnutrition and environmental stimulation on behavioral and biochemical parameters in rats submitted to the elevated plus-maze test

“…Plasma CORT levels were obtained through the radioimmunoassay method as described by Elias et al 36,37 The anti-corticosterone antibody was kindly supplied by Dr José Gilberto Vieira (Federal University of São Paulo, Brazil) and the 1,2,6,7-3H corticosterone was bought from GE Healthcare Life Sciences (USES). The assay sensibility and the intra-and inter-assay coefficient variations were 0.4 μg/dL, 5.1 and 8.4%, respectively.…”