Expression of mRNAs for vasopressin, oxytocin and corticotrophin releasing hormone in the hypothalamus, and of cyclooxygenases-1 and -2 in the cerebral vasculature, of endotoxin-challenged pigs.

Neuropeptide and cyclooxygenase (Cox) gene expression was examined in the brains of catheterized pigs killed 30 or 120 min after intravenous injection of a low (20 microg) dose of lipopolysaccharide endotoxin (LPS), previously demonstrated to induce fever in this species. In the paraventricular hypothalamic nucleus (PVN), corticotrophin releasing hormone (CRH) mRNA was shown to be present in the pars parvocellularis but was not upregulated 30 or 120 min after 20 microg LPS, or 90 min after 60 microg LPS; there was also no change in proopiomelanocortin (POMC) message in the anterior pituitary (AP). Similarly, expression of mRNAs for lysine vasopressin (LVP) or oxytocin (OT) did not change in the PVN after LPS (20 microg), although LVP message was increased (p<0.05) at 30 min in the hypothalamic supraoptic nucleus (SON). Expression of Cox-1 and Cox-2 genes was quantified in the organum vasculosum lamina terminalis (OVLT) and choroid plexus (CP) in an attempt to determine whether altered expression of prostaglandin (PG) synthetic enzymes in brain vasculature is involved in LPS fever. Although vascular endothelial cells in both structures expressed Cox-1 and Cox-2 mRNAs, neither increased in the OVLT following LPS. However, in the CP, Cox-1 mRNA was enhanced (p<0.05) at 30 and 120 min after LPS injection and Cox-2 showed a similar (NS) change. These results provide the first description of CRH and Cox gene expression in the porcine brain. They also suggest that LPS may influence the activity of genes controlling LVP synthesis in the hypothalamus and PG production by the brain vasculature.