Tags

Type your tag names separated by a space and hit enter

Recovery of the rat hypothalamic-pituitary-adrenal axis after discontinuation of prolonged treatment with the synthetic glucocorticoid agonist dexamethasone.
Endocrinology. 1990 Oct; 127(4):1574-9.E

Abstract

To evaluate the recovery of the hypothalamic-pituitary-adrenal (HPA) axis after discontinuation of prolonged exposure to glucocorticoids, we employed adult male Sprague-Dawley rats which were implanted sc with osmotic minipumps filled with saline (vehicle) or dexamethasone (DEX), 100 micrograms/day, for 7 days. At the end of the glucocorticoid treatment period, the minipumps were removed and both saline- and DEX-treated rats were randomly assigned to five different groups tested at 1, 3, 7, 14, and 21 days after removal of the minipumps. Each group was divided into two subgroups receiving either arecoline (ARE), or ovine CRH (oCRH) stimulation tests. ARE was chosen because it has been shown to selectively stimulate the hypothalamic CRH neuron, whereas oCRH was selected as a probe of the pituitary component of the HPA axis. ARE (0.2 mg/kg) and oCRH (10 micrograms/kg) were injected iv to catheterized, freely moving rats and serial blood samples for plasma ACTH and corticosterone determinations were drawn from the catheter before, and 5, 15, 30, and 60 min after the injection. The day after the tests were performed, the rats were killed by decapitation, and body, adrenal and thymus weights, as well as hypothalamic CRH and pituitary ACTH content were determined. On the day of the stimulation tests, basal plasma levels of ACTH and corticosterone were not different between saline- and DEX-treated rats at any time-point after discontinuation of treatment. The ACTH response to ARE, on the other hand, was suppressed one day after, but became normal 3 days after discontinuation of DEX treatment. ACTH response to oCRH normalized later, after 7 days. Interestingly, corticosterone responses to both ARE and oCRH normalized 7 days after discontinuation of glucocorticoid administration. Body, adrenal and thymus weights were significantly reduced by DEX treatment. They recovered slowly and only after 22 days there was no difference between DEX- and saline-treated rats in body and adrenal weight. In contrast, thymus weight was still low on day 8, began to increase after 15 days, and by day 22 did not reach the values recorded in saline-treated rats. Hypothalamic immunoreactive CRH content was not different between DEX- and saline-treated rats, whereas the content of ACTH in the pituitary gland was lower in the DEX-treated rats the second day after discontinuation of GC treatment, normalized after 4 days and increased significantly after 8 days.(ABSTRACT TRUNCATED AT 400 WORDS)

Authors+Show Affiliations

Developmental Endocrinology Branch, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892.No affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article

Language

eng

PubMed ID

2169393

Citation

Calogero, A E., et al. "Recovery of the Rat Hypothalamic-pituitary-adrenal Axis After Discontinuation of Prolonged Treatment With the Synthetic Glucocorticoid Agonist Dexamethasone." Endocrinology, vol. 127, no. 4, 1990, pp. 1574-9.
Calogero AE, Kamilaris TC, Johnson EO, et al. Recovery of the rat hypothalamic-pituitary-adrenal axis after discontinuation of prolonged treatment with the synthetic glucocorticoid agonist dexamethasone. Endocrinology. 1990;127(4):1574-9.
Calogero, A. E., Kamilaris, T. C., Johnson, E. O., Tartaglia, M. E., & Chrousos, G. (1990). Recovery of the rat hypothalamic-pituitary-adrenal axis after discontinuation of prolonged treatment with the synthetic glucocorticoid agonist dexamethasone. Endocrinology, 127(4), 1574-9.
Calogero AE, et al. Recovery of the Rat Hypothalamic-pituitary-adrenal Axis After Discontinuation of Prolonged Treatment With the Synthetic Glucocorticoid Agonist Dexamethasone. Endocrinology. 1990;127(4):1574-9. PubMed PMID: 2169393.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Recovery of the rat hypothalamic-pituitary-adrenal axis after discontinuation of prolonged treatment with the synthetic glucocorticoid agonist dexamethasone. AU - Calogero,A E, AU - Kamilaris,T C, AU - Johnson,E O, AU - Tartaglia,M E, AU - Chrousos,G, PY - 1990/10/1/pubmed PY - 1990/10/1/medline PY - 1990/10/1/entrez SP - 1574 EP - 9 JF - Endocrinology JO - Endocrinology VL - 127 IS - 4 N2 - To evaluate the recovery of the hypothalamic-pituitary-adrenal (HPA) axis after discontinuation of prolonged exposure to glucocorticoids, we employed adult male Sprague-Dawley rats which were implanted sc with osmotic minipumps filled with saline (vehicle) or dexamethasone (DEX), 100 micrograms/day, for 7 days. At the end of the glucocorticoid treatment period, the minipumps were removed and both saline- and DEX-treated rats were randomly assigned to five different groups tested at 1, 3, 7, 14, and 21 days after removal of the minipumps. Each group was divided into two subgroups receiving either arecoline (ARE), or ovine CRH (oCRH) stimulation tests. ARE was chosen because it has been shown to selectively stimulate the hypothalamic CRH neuron, whereas oCRH was selected as a probe of the pituitary component of the HPA axis. ARE (0.2 mg/kg) and oCRH (10 micrograms/kg) were injected iv to catheterized, freely moving rats and serial blood samples for plasma ACTH and corticosterone determinations were drawn from the catheter before, and 5, 15, 30, and 60 min after the injection. The day after the tests were performed, the rats were killed by decapitation, and body, adrenal and thymus weights, as well as hypothalamic CRH and pituitary ACTH content were determined. On the day of the stimulation tests, basal plasma levels of ACTH and corticosterone were not different between saline- and DEX-treated rats at any time-point after discontinuation of treatment. The ACTH response to ARE, on the other hand, was suppressed one day after, but became normal 3 days after discontinuation of DEX treatment. ACTH response to oCRH normalized later, after 7 days. Interestingly, corticosterone responses to both ARE and oCRH normalized 7 days after discontinuation of glucocorticoid administration. Body, adrenal and thymus weights were significantly reduced by DEX treatment. They recovered slowly and only after 22 days there was no difference between DEX- and saline-treated rats in body and adrenal weight. In contrast, thymus weight was still low on day 8, began to increase after 15 days, and by day 22 did not reach the values recorded in saline-treated rats. Hypothalamic immunoreactive CRH content was not different between DEX- and saline-treated rats, whereas the content of ACTH in the pituitary gland was lower in the DEX-treated rats the second day after discontinuation of GC treatment, normalized after 4 days and increased significantly after 8 days.(ABSTRACT TRUNCATED AT 400 WORDS) SN - 0013-7227 UR - https://www.unboundmedicine.com/medline/citation/2169393/Recovery_of_the_rat_hypothalamic_pituitary_adrenal_axis_after_discontinuation_of_prolonged_treatment_with_the_synthetic_glucocorticoid_agonist_dexamethasone_ L2 - https://academic.oup.com/endo/article-lookup/doi/10.1210/endo-127-4-1574 DB - PRIME DP - Unbound Medicine ER -