DPDPE dependence

Those related to the respiratory apparatus are of special interest DPDPE causes a dose dependent increase in foetal respiratory activity which was blocked by administration of naloxone (Cheng et al., 1992). These stimulatory effects of selective 5 agonists may be of clinical value in treating respiratory disorders such as apnoea. 

The role of Gpy, released from pertussis toxin-sensitive G proteins, in coupling activated receptor to effectors further complicates specificity. Delta opioids activate G protein-coupled inwardly rectifying K+ channels [50] activation of such channels occurs by direct binding of Gp-y to various regions of the channel [51]. Delta agonist-mediated increase in the release of Ca2+ from intracellular stores in NG108-15 cells is mediated by Gp-y subunits [52], and Gp antibodies inhibited DPDPE stimulated PLC-p activation and, therefore, Ins(l,4,5)P3-dependent Ca2+ release and smooth muscle contraction in intestinal smooth muscle cells of the guinea pig [46]. However, the Ga... 

There is considerable evidence that 5r and 2-opioid receptors act at supraspinal sites to modulate nociceptive responses. Direct ICV injection of the putative 5-opioid agonists DPDPE or DPLPE in the mouse produced dose-dependent antinociception that was blocked by ICI 174,864 but not by (5-FNA [87,88]. Furthermore, 5-opioid selective doses of DPDPE given ICV blocked nociception, but not gastrointestinal transit, in mice [99].The ICV administration of DPDPE has been shown to produce dose-dependent antinociception against mechanical nociception (Randall-Selitto paw with-... 

In mucosal sheets from porcine ileum, the delta opioid agonist DPDPE inhibits saxitoxin-sensitive elevations in neurogenic ion transport evoked by histamine [142], tryptase-like enzymes [143], serotonin [144], kallidin [145], and type I hypersensitivity [142]. These effects of DPDPE are inhibited by naltrindole. In contrast, elevations in neurogenic ion transport occurring secondary to an immediate hypersensivity reaction in the guinea pig ileal mucosa are augmented by DPDPE, indicating that the neuromodulatory actions of opioids on active mucosal transport evoked by inflammation or anaphylaxis may depend on the species examined [146],... 

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