[Dexamethasone regulate the neuropeptide expression in rabbit's brain injury induced by endotoxin]

To investigate whether dexamethasone (DXM) regulate the expression of Calcitonin gene-related peptide (CGRP), Endothelin (ET), Atrial natriuretic peptide (ANP), Angiotensin II (AII) in brain injury induced by endotoxin in rabbit.

Sixty-five New Zealand white rabbits were randomly divided into 3 subgroups: endotoxin group (A group), endotoxin + DXM group (B group) and normal saline group (C group). 100 microg/kg endotoxin was intracerebroventricularly injected in A group, endotoxin 100 microg/kg + DXM 1 mg/kg in B group and same volume of normal saline in C group as control. Neuropeptide level were detected by radioimmunoassay in variable periods (3 h, 6 h, 12 h, 24 h, 48 h, 72 h after injection) in the plasma, cerebrospinal fluid (CSF) and brain tissue (hippocampus area), and brain water content was measured by dry method.

CGRP, ET, ANP, AII concentrations in plasma, CSF and brain tissue changed in variable periods after injection. The higher or the lower neuropeptide levels were emerged on 12 - 24 hours after injection (P < 0.05 or P < 0.01), and changed remarkably in A group (P < 0.05 or P < 0.01). Brain water content were significantly higher and reached to peak level on 24 hours after injection. But there was a significantly increasing in A group compared to that of B group (P < 0.05 or P < 0.01).

The timely changes of CGRP, ET, ANP, AII were related to brain injury and brain edema induced by endotoxin, and DXM regulated the expression of neuropeptides and lighten brain edema.