Anti-nociceptive and anti-allodynic effects of a high affinity NOP hexapeptide [Ac-RY(3-Cl)YRWR-NH2] (Syn 1020) in rodents.

There has been a flurry of activity to develop agonists and antagonists for the member of the opioid receptor family, NOP receptor (also known as ORL1), in part to understand its role in pain. Modifications of a hexapeptide originally identified from a combinatorial library have led to the discovery of a high affinity hexapeptide agonist Ac-RY(3-Cl)YRWR-NH2 (Syn 1020). In the following experiments we characterized the anti-nociceptive effects of Syn 1020 in the tail-flick model of acute pain and the diabetic neuropathy model of chronic pain in mice and rats, respectively. Acute antinociception was assessed using the tail-flick assay in mice in which animals received intracerebroventricular (i.c.v.) or subcutaneous (s.c.) injections of Syn 1020 alone or with morphine and were tested for tail-flick latencies. In the chronic pain model, diabetic neuropathy was induced by injections of streptozotocin in rats. Tactile allodynia was measured, with von Frey hair filaments, following intraperitoneal (i.p.) injections of Syn 1020 or gabapentin (positive control). In mice, i.c.v. injections of Syn 1020 did not have any pro- or anti-nociceptive effects, however, Syn 1020 reversed morphine antinociception with a similar potency as N/OFQ (the natural ligand to NOP). S.c. injections of Syn 1020 in mice also produced analgesic effects. In rats, i.p, injections of Syn 1020 produced anti-allodynic effects. Thus, Syn 1020, a NOP receptor directed peptide, administered systemically has anti-nociceptive activity in both acute and chronic pain models in mice and rats respectively.

Conserved cysteine and histidine residues in the putative zinc finger motif of the influenza A virus M1 protein are not critical for influenza virus replication.

The influenza virus matrix protein (M1) possesses a cysteine and histidine (CCHH) motif in the helix 9 (H9) and adjacent region ((148)CATCEQIADSQHRSH(162)). The CCHH motif has been proposed as a putative zinc finger motif and zinc-binding activity has been implicated in virus uncoating as well as transcription inhibition and mRNA regulation. The function of the CCHH motif in the influenza virus life cycle was investigated by site-directed mutagenesis (alanine replacement) and by rescuing mutant viruses by reverse genetics. Mutant viruses containing an alanine replacement of the cysteine and histidine residues, either individually or in combination, were seen to exhibit wt phenotype in multiple virus growth cycles and plaque morphology. In addition, synthetic peptides containing the putative zinc finger motif did not inhibit virus replication in MDCK cells. However, mutation of Ala(155) in H9 was lethal for rescuing infectious virus. These data show that the CCHH motif does not provide a critical function in the influenza virus life cycle in cell culture and that the zinc-binding function may not be involved in virus biology. However, the lethal phenotype of the Ala(155) mutation shows that the H9 region of M1 provides some other critical function(s) in virus replication.