the effect of nmda (n-methyl-d-aspartate) receptor antagonists on tolerance to morphine antinociception was investigated in mice. daily subcutaneous administration of 50 mg/kg of morphine hydrochloride for three days induced tolerance to different (3,6 and 9 mg/kg) test doses of morphine. the tolerance obtained was decreased by pretreatment of animals with single or repeated doses of competitiv...

lthough Zn 2 is contained in large amounts in the synaptic terminals of hippocampal mossy fibers (MFs), its physiological role in synaptic transmission is poorly understood. By using the newly developed high-sensitivity Zn 2 indicator ZnAF-2, the spatiotemporal dynamics of Zn 2 was monitored in rat hippocampal slices. When high-frequency stimulation was delivered to the MFs, the concentration o...

BACKGROUND The aspartate receptor is a transmembrane protein that mediates bacterial chemotaxis. The structures of the periplasmic ligand-binding domain reveal a dimer, each subunit with four alpha-helix bundles, with aspartate binding to one of two sites at the subunit interface. The transmembrane regions of the receptor were not included in these structures. RESULTS To investigate the struc...

The human bacterial pathogen Campylobacter jejuni is able to respond to environmental stimuli utilising chemotactic motility. The bacterial senses external molecules via transmembrane sensory proteins called Transducer Like Proteins, TLPs. The specificity of the Tlp1 chemoreceptor (Cj1506c) of C. jejuni as the aspartate receptor, CcaA, and its role in chemotaxis signalling pathway were characte...

We mutated a conserved aspartate in the second transmembrane domain of the cannabinoid CB(1) receptor to asparagine (D164N), stably transfected it into AtT20 cells, and examined the coupling of this mutant receptor to several intracellular effectors that are targets of wild-type CB(1) receptor activation. We found that the D164N receptor binds the CB(1) agonist WIN 55,212-2 with an affinity mat...