The ORL1 receptor, an orphan receptor whose human and murine complementary DNAs have recently been characterized, structurally resembles opioid receptors and is negatively coupled with adenylate cyclase. ORL1 transcripts are particularly abundant in the central nervous system. Here we report the isolation, on the basis of its ability to inhibit the cyclase in a stable recombinant CHO(ORL1+) cell line, of a neuropeptide that resembles dynorphin A9 and whose amino acid sequence is Phe-Gly-Gly-Phe-Thr-Gly-Ala-Arg-Lys-Ser-Ala-Arg-Lys-Leu-Ala-Asn-Gln. The rat-brain cDNA encodes the peptide flanked by Lys-Arg proteolytic cleavage motifs. The synthetic heptadecapeptide potently inhibits adenylate cyclase in CHO(ORL1+) cells in culture and induces hyperalgesia when administered intracerebroventricularly to mice. Taken together, these data indicate that the newly discovered heptadecapeptide is an endogenous agonist of the ORL1 receptor and that it may be endowed with pro-nociceptive properties.

Selective PCR amplification of human and mouse genomic DNAs with oligonucleotides encoding highly conserved regions of the S-opioid and somatostatin receptors generated a human DNA probe (hOPO1, 761 bp) and its murine counterpart (mOP86, 447 bp). hOPO1 was used to screen a cDNA library from human brainstem. A clone (named hORL1) was isolated, sequenced and found to encode a protein of 370 amino acids whose primary structure displays the seven putative membrane-spanning domains of a G protein-coupled membrane receptor. The hORL1 receptor is most closely related to opioid receptors not only on structural (sequence) but also on functional grounds: hORL1 is 49-50% identical to the murine ,u-, 6-and rc-opioid receptors and, in CHO-Kl cells stably transfected with a pRc/CMV:hORLl construct, ORLl mediates inhibition of adenylyl cyclase by etorphine, a 'universal' (nonselective) opiate agonist. Yet, hORL1 appears not to be a typical opioid receptor. Neither is it a somatostatin or o (N-allylnormetazocine) receptor. mRNAs hybridizing with synthetic oligonucleotides complementary to mOP86 are present in many regions of the mouse brain and spinal cord, particularly in limbic (amygdala, hippocampus, septum, habenula, . . .) and hypothalamic structures. We conclude that the hORL1 receptor is a new member of the opioid receptor family with a potential role in modulating a number of brain functions, including instinctive behaviours and emotions.

Cisplatin (cis-diamminedichloroplatinum(II») is widely used in the treatment of testicular and ovarian cancers. A number of biological and biochemical results indicate that the reaction of cisplatin with DNA is responsible for the cytotoxic action of this drug. The effect of platinum compounds on the conformation and stability of DNA has been investigated and several platinum-DNA adducts have been identified in vitro and in vivo. Preliminary experiments have quantified the effect of these different lesions on DNA replication, their capacity to induce mutations and their susceptibility to DNA repair processes. Additional DNA damage may be created by platinum(IV) compounds, perhaps during their reduction to platinum(II) compounds by the cell.