l-365260 and Inflammation

Controlling the inflammatory cascade during sepsis remains a major clinical challenge. Recently, it has become evident that the autonomic nervous system reduces inflammation through the vagus nerve. The current study investigates whether nutritional stimulation of the autonomic nervous system effectively attenuates the inflammatory response in murine Gram-negative sepsis.. Controlled in vivo and ex vivo experimental study.. Research laboratory of a university hospital.. Male C57bl6 mice.. Mice were intraperitoneally challenged with lipopolysaccharide derived from Escherichia coli. Before lipopolysaccharide administration, mice were fasted or enterally fed either lipid-rich nutrition or low-lipid nutrition. Antagonists to cholecystokinin receptors or nicotinic receptors were administered before lipopolysaccharide administration. Blood and tissue samples were collected at 90 mins. Mesenteric afferent discharge was determined in ex vivo preparations in response to both nutritional compositions.. Both lipid-rich and low-lipid nutrition dose-dependently reduced lipopolysaccharide-induced tumor necrosis factor-α release (high dose: both 1.4 ± 0.4 ng/mL) compared with fasted mice (3.7 ± 0.8 ng/mL; p < .01). The anti-inflammatory effect of both nutritional compositions was mediated through cholecystokinin receptors (p < .01), activation of mesenteric vagal afferents (p < .05), and peripheral nicotinic receptors (p < .05). Lipid-rich nutrition attenuated the inflammatory response at lower dosages than low-lipid nutrition, indicating that enrichment of enteral nutrition with lipid augments the anti-inflammatory potential. Administration of lipid-rich nutrition prevented endotoxin-induced small intestinal epithelium damage and reduced inflammation in the liver and spleen compared with fasted (all p < .01) and low-lipid nutrition controls (all p < .05).. The current study demonstrates that lipid-rich nutrition attenuates intestinal damage and systemic as well as organ-specific inflammation in murine Gram-negative sepsis through the nutritional vagal anti-inflammatory pathway. These findings implicate enteral administration of lipid-enriched nutrition as a promising intervention to modulate the inflammatory response during septic conditions.

Topics: Animals; Benzodiazepinones; Chlorisondamine; Devazepide; Disease Models, Animal; Endotoxemia; Enteral Nutrition; Inflammation; Lipids; Lipopolysaccharides; Male; Mice; Mice, Inbred C57BL; Phenylurea Compounds; Receptors, Cholecystokinin; Sepsis; Tumor Necrosis Factor-alpha

Previous studies suggest that cholecystokinin (CCK) is implicated in the modulation of pain sensitivity and the development of neuropathic pain. We used CCK(2) receptor deficient (CCK(2) (-/-)) mice and assessed their mechanical sensitivity using Von Frey filaments, as well as the development and time course of mechanical hyperalgesia in a model of neuropathic pain. We found that CCK(2) (-/-) mice displayed mechanical hyposensitivity, which was reversed to the level of wild-type animals after administration of naloxone (0.1-10 mg/kg). On the other hand, injection of L-365260 (0.01-1 mg/kg), an antagonist of CCK(2) receptors, decreased dose-dependently, mechanical sensitivity in wild-type mice. The mechanism of reduced mechanical sensitivity in CCK(2) (-/-) mice may be explained by changes in interactions between CCK and opioid systems. Indeed, CCK(2) (-/-) mice natively expressed higher levels of lumbar CCK(1), opioid delta and kappa receptors. Next, we found that CCK(2) (-/-) mice did not develop mechanical hyperalgesia in the Bennett's neuropathic pain model. Induction of neuropathy resulted in decrease of lumbar pro-opiomelanocortin (POMC) gene expression in wild-type mice, but increase of POMC expression in CCK(2) (-/-) mice. In addition, induction of neuropathy resulted in further increase of opioid delta receptor in CCK(2) (-/-) mice. Gene expression results indicate up-regulation of opioid system in CCK(2) (-/-) mice, which apparently result in decreased neuropathy score. Our study suggests that not only pain sensitivity, but also mechanical sensitivity and the development of neuropathic pain are regulated by antagonistic interactions between CCK and opioid systems.

Topics: Animals; Benzodiazepinones; Disease Models, Animal; Dose-Response Relationship, Drug; Dynorphins; Enkephalins; Gene Expression; Hyperalgesia; Inflammation; Ligation; Male; Mice; Mice, Inbred C57BL; Mice, Knockout; Naloxone; Narcotic Antagonists; Pain Measurement; Pain Threshold; Phenylurea Compounds; Pro-Opiomelanocortin; Protein Precursors; Receptor, Cholecystokinin B; Receptors, Cholecystokinin; Receptors, Opioid; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; Sciatic Neuropathy; Time Factors

1. Cholecystokinin (CCK) has been shown to diminish opioid analgesia. Here we investigate whether changes in the physiological levels of spinal CCK are responsible for the enhanced potency of spinal morphine in animals following carrageenin inflammation, as compared with normal animals. 2. Single dorsal horn nociceptive neurones were recorded in intact halothane-anaesthetized rats in the presence and absence of carrageenin-induced inflammation and comparisons were made between the two groups of animals. Inflammation was induced by the injection of 100 microliters of 2% lambda-carrageenin into the hind paw. 3. The inhibitory effect of intrathecal morphine on the C-fibre-evoked responses of the neurones was enhanced in the carrageenin-treated animals such that the effects of 0.25 microgram and 10 micrograms of morphine in normal animals were comparable to those of 0.01 microgram and 2.5 micrograms in the carrageenin animals. The effect of 0.2 mg kg-1 of the CCKB antagonist, L-365,260, on the antinociceptive potency of intrathecal morphine was examined in both groups of animals. In normal animals, L-365,260 produced a significant enhancement in the effect of morphine indicating a tonic CCK modulation in these animals, but it had no effect on the inhibitions produced by either dose of morphine in the carrageenin animals. 4. The inhibition of the C-fibre-evoked response produced by intrathecal morphine in the presence of 1 microgram of CCK was examined in both groups of animals. CCK attenuated the effects of morphine only in animals with carrageenin inflammation, having no effect on the action of morphine in normal animals. 5. The effects of both CCK and L-365,260 were therefore dependent on the inflammatory state of the animal, with each drug being active in opposite situations.6. We propose that in normal animals, morphine may produce a maximal stimulation of the release of CCK such that exogenous CCK is unable to reduce further the analgesic effects under these conditions.However, the differential effects of the agonist and antagonist in the normal and inflamed rats points to a role of CCK in the enhanced opiate actions. This enhancement of the potency of spinal morphine in inflammation is best explained by a reduction in spinal CCK release by morphine in this state.

Topics: Animals; Benzodiazepinones; Carrageenan; Cholecystokinin; Inflammation; Injections, Spinal; Male; Morphine; Nerve Fibers; Phenylurea Compounds; Rats; Rats, Sprague-Dawley; Sincalide; Spinal Cord