Objective: To observe the changes in ultrastructure and function of hypothalamic-pituitary-adrenal axis (HPAA), and to approach the relationship between them in early stage of sepsis in rats.
Methods: Thirty male Sprague-Dawley (SD) rats were randomly divided into normal control group, sham group, sepsis group. The sepsis model was reproduced by cecal ligation and puncture (CLP). The rats were sacrificed after collection of blood at 6 hours after CLP, and the levels of adrenocorticotropic hormone (ACTH) and corticosterone (CORT) in the plasma, and the corticotropin release hormone (CRH) in the tissue of hypothalamus were detected. The histopathological changes in HPAA were observed with transmission electron microscopy.
Results: The levels of ACTH and CORT in plasma, and the CRH in hypothalamus tissue of sepsis group were increased in the early stage of sepsis compared with the normal control group or sham group [ACTH (pmol/L): 5.78±0.36 vs. 1.94±0.31, 2.51±0.10; CORT (nmol/L): 88.48±4.47 vs. 22.02±1.62, 34.20±2.51; CRH (μg/L): 101.92±6.61 vs. 61.65±6.05, 66.65±4.03, P<0.05 or P<0.01]. The changes in ultrastructure of the hypothalamus, pituitary and adrenal were also found. In sepsis group, the ultrastructure of hypothalamus was as follows. Rough endoplasmic reticulum expansion and degranulation of rough endoplasmic reticulum, and swelling of Golgi complex were found. A large number of endocrine granules could be seen in ATCH cells in the pituitary with depletion of adrenal lipid droplets.
Conclusion: In septic rats, the HPAA was excessively activated, and ACTH and CORT in plasma, and CRH in hypothalamus were significantly increased in early stage of sepsis. The changes in ultrastructure of HPAA were obvious, and the change in function was closely related to the ultrastructural changes.