Interleukin-1 is not essential for expression of inducible NOS in hepatocytes induced by lipopolysaccharide in vivo.

Interleukin (IL)-1 and tumor necrotic factor alpha (TNFalpha) are pivotal in the pathogenesis of endotoxemia. In spite of the in vitro finding that IL-1beta, but not TNFalpha, can induce iNOS mRNA and NO production as a single stimulus in hepatocytes in primary culture, the involvement of IL-1 in iNOS induction in the liver has been less clear in vivo. To address this, we challenged IL-1alpha/beta double-knockout (IL-1alpha/beta(-/-)) and TNFalpha(-/-) mice with lipopolysaccharide (LPS).

Fyn kinase-mediated phosphorylation of NMDA receptor NR2B subunit at Tyr1472 is essential for maintenance of neuropathic pain.

Despite abundant evidence implicating the importance of N-methyl-D-aspartate (NMDA) receptors in the spinal cord for pain transmission, the signal transduction coupled to NMDA receptor activation is largely unknown for the neuropathic pain state that lasts over periods of weeks. To address this, we prepared mice with neuropathic pain by transection of spinal nerve L5. Wild-type, NR2A-deficient, and NR2D-deficient mice developed neuropathic pain; in addition, phosphorylation of NR2B subunits of NMDA receptors at Tyr1472 was observed in the superficial dorsal horn of the spinal cord 1 week after nerve injury.

Rho-kinase mediates spinal nitric oxide formation by prostaglandin E2 via EP3 subtype.

Prostaglandin E2 (PGE2), the principal pro-inflammatory prostanoid, is known to play versatile roles in pain transmission via four PGE receptor subtypes, EP1-EP4. We recently demonstrated that continuous production of nitric oxide (NO) by neuronal NO synthase (nNOS) following phosphorylation of myristoylated alanine-rich C-kinase substrate (MARCKS) and NMDA receptor NR2B subunits is essential for neuropathic pain. These phosphorylation and nNOS activity visualized by NADPH-diaphorase histochemistry were blocked by indomethacin, a PG synthesis inhibitor.

In situ measurement of neuronal nitric oxide synthase activity in the spinal cord by NADPH-diaphorase histochemistry.

NADPH-diaphorase (NADPH-d) histochemistry has provided a simple method to stain neuronal nitric oxide synthase (nNOS)-containing neurons in the central nervous system. In the spinal cord, NO formation following activation of N-methyl-D-asparate (NMDA) receptors plays a crucial role in nociceptive processing. To investigate the molecular mechanisms, we attempted to evaluate nNOS activity in situ using isolated intact spinal cord preparation and NADPH-d histochemistry.

Membrane-associated prostaglandin E synthase-1 is required for neuropathic pain.

It is widely accepted that prostaglandin (PG) E2 is the principal pro-inflammatory prostanoid and plays an important role in inflammatory pain. However whether PGE2 is involved in neuropathic pain remains unknown. PGE2 is produced from arachidonic acid via PGH2 by at least three PGE synthases (PGES), cytosolic PGES (cPGES), and membrane-associated PGES (mPGES)-1 and -2.