[Structure of Neuroglobin from Cold-Water Sponge Halisarca dujardinii].

The iron-containing protein neuroglobin (Ngb) involved in the transport of oxygen is generally considered the precursor of all animal globins. In this report, we studied the structure of Ngb of the cold-water sponge Halisarca dujardinii. In sponges, the oldest multicellular organisms, the Ngb gene contains three introns. In contrast to human Ngb, its promoter contains a TATA-box, rather than CG-rich motifs. In sponges, Ngb consists of 169 amino acids showing rather low similarity with its mammalian orthologues. It lacks Glu and Arg residues in positions required for prevention of hypoxia-related apoptosis. Nevertheless, Ngb contains both proximal and distal conserved heme-biding histidines. The primary structure of H. dujardinii neuroglobin predicted by sequencing was confirmed by mass-spectrometry analysis of recombinant Ngb expressed in E. coli. The high level of Ngb expression in sponge tissues suggests its possible involvement in the gas metabolism and presumably in other key metabolic processes in H. dujardinii.

Inhibitors of Ca(2+)-dependent endopeptidases modulate morphine-induced effects in rats.

The effects of inhibitors of Ca(2+)-dependent endopeptidases (antipain and leupeptin) on morphine analgesia, reinforcing properties of morphine and on the development of opiate physical dependence were studied. Male Wistar rats were used. The analgesic action of morphine in the tail-immersion test was increased significantly by combined injection of morphine with antipain or leupeptin. Antipain or leupeptin alone had no analgesic action. The combination of morphine with antipain or leupeptin led to the reduction of morphine-induced place preference and the development of physical dependence. A single injection of antipain diminished the opiate-withdrawal signs in morphine-dependent rats. These results suggest a possible inhibitory effect of antipain or leupeptin on the Ca(2+)-dependent endopeptidases of neurons that mediate analgesia, reinforcing properties of morphine, development of opiate dependence and withdrawal.

Influence of inheritance and fostering on sensitivity to effects of morphine on nociception and locomotor activity in two inbred rat strains.

There are differences between individuals in their pain threshold, locomotor activity, and sensitivity to drugs of abuse which affect these processes. We have investigated the role of genetic differences and fostering in determining sensitivity to the action of morphine on nociception and locomotor activity in two strains of rats [Fischer-344 (F) and WAG/G (W)], using methods of reciprocal cross and cross-fostering. Nine-week old rats were used in the experiments. It was found that FF rats were more sensitive to the action of morphine on locomotor activity in open field apparatus than WW rats. Both types of F1 hybrids inherited a low sensitivity to the depressive action of morphine, their activity significantly differed from FF activity and had no distinction from that of WW rats. However, there was a strong maternal effect: if WW rats were fostered by a FF mother, the depression of their locomotor activity was similar to that of FF inbred rats, and vice versa. There were significant differences between normal and cross-fostered rats in all groups. WW rats had a higher sensitivity to thermal stimuli than FF rats. Both types of hybrids had intermediate nociceptive latencies. The strain difference between WW and FF rats in the baseline latencies of tail withdrawal disappeared after crossfostering-the latencies in FF rats were significantly decreased. Administration of morphine produced greater antinociception in FF rats than in WW. Cross-fostering of FF rats by WW mothers dramatically decreased their sensitivity to the analgesic action of morphine, while WW rats fostered by FF mothers did not change their resistance to morphine induced antinociception. Thus, the sensitivity of young rats to morphine-induced analgesia or depression of locomotor activity is mostly determined by fostering during the first 21 days.