p.), ghrelin alone (0.1 mg/kg, 1 ml/kg, i.p.) or ghrelin combined with LPS. Control rats were treated with pyrogen-free saline (1 ml/kg, i.p.). The doses of LPS [22] and ghrelin [34] were chosen on the basis of previous studies and pilot experiments. Experiment 2: The second set of experiments was aimed at evaluating whether ghrelin

affects the febrigenic signaling in the brain EPZ5676 molecular weight as well as the modulation of febrile response by the endogenous glucocorticoids. The levels of PGE2 (the terminal mediator of fever) in its presumed site of action – the preoptic/anteroventral third ventricular region [4], [17] and [23] – was used as an index of febrigenic signaling, and plasma corticosterone to assess the hypothalamic-pituitary-adrenal

axis activation. Animals were bolus-injected with LPS (50 μg/kg, 1 ml/kg; or saline, 1 ml/kg, i.p.), combined or not with ghrelin (0.1 mg/kg, 1 ml/kg, i.p.), and decapitated 2 h post-injection. Trichostatin A purchase The brains were then immediately excised from the skull and promptly frozen by immersion into isopentane cooled with dry ice, and blood was collected for corticosterone measurements. This experiment was aimed at evaluating PGE2 production (cyclooxygenase, COX, activity) in the preoptic/AV3V region, as previously described [1] and [26]. Briefly, 2 h after injections rats were decapitated, their brains immediately excised, and the AV3V, which includes the preoptic region, was dissected. The AV3V region was cut at its borders with the vertical limb of the diagonal band of Broca (anterior), the posterior end of the optic chiasm (posterior), the ventral thalamus (dorsal), and the lateral

hypothalamus (lateral); the ventral limit of the AV3V region was the optic chiasm. The samples were frozen by immersion in liquid nitrogen and stored at −70 °C until assayed. They were homogenized on ice in methanol (150 μl) containing indomethacin (1 M). The homogenates were centrifuged at 10,000 × g for 10 min at 2 °C. The resulting supernatants and pellets were used for PGE2 and protein determination, respectively. The samples were reconstituted in the assay Ribonucleotide reductase buffer provided in the kit (Cayman, 500141 Prostaglandin E2 EIA Kit), and PGE2 levels were measured using enzyme immunoassay according to the manufacturer’s instructions. To assess hypothalamic-pituitary-adrenal axis activation trunk blood was collected (∼2 ml). Animals were sampled without anesthesia. Control and experimental animals were removed from their cages and decapitated within 10 s [31]. Blood was allowed to coagulate at 4 °C overnight. Samples were centrifuged at 1500 × g for 10 min; plasma was sampled and stored at −70 °C until assay. Total plasma corticosterone (free and bound) was determined by a commercially available ELISA kit, according to the manufacturer’s instructions (Cayman Chemical, Ann Arbor, MI, USA). Results are expressed as mean ± standard error of the mean (SEM).