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Opioid-induced stimulation of fetal respiratory activity by [D-Ala2]deltorphin I

https://doi.org/10.1016/0014-2999(93)90413-CGet rights and content
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Abstract

[D-Ala2]deltorphin I effects on fetal respiratory activity was characterized to determine the role δ-opioid receptors play in modulating fetal respiratory activity. [D-Ala2]deltorphin I, infused at 0.3 or 100 μg/h, intracerebroventricularly (i.c.v.), stimulated fetal respiratory activity without changing blood pH, PCO2 or PO2. Stimulation by 0.3 μg/h, but not 100 μg/h, was blocked by i.c.v. infusion of the δ-opioid receptor antagonist, naltrindole. Stimulation by 100 μg/h was blocked by the μ1-opioid receptor antagonist naloxonazine. These data suggest stimulation of fetal respiratory activity by 0.3 μg/h [D-Ala2]deltorphin I are mediated specifically through δ-opioid receptors; while [D-Ala2]deltorphin I at 100 μg/h is no longer selective for the δ-opioid receptor, and the stimulation may be mediated through the μ1-opioid receptor.

Keywords

Fetal breathing
Opiates
δ-Opioid receptors
[D-Ala2]deltorphin
Naltrindole
Naloxonazine

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