Opiate receptor blockade on human granulosa cells inhibits VEGF release.

The objectives of this study were to determine whether the main opioid receptor (OPRM1) is present on human granulosa cells and if exogenous opiates and their antagonists can influence granulosa cell vascular endothelial growth factor (VEGF) production via OPRM1. Granulosa cells were isolated from women undergoing oocyte retrieval for IVF. Complementary to the primary cells, experiments were conducted using COV434, a well-characterized human granulosa cell line. Identification and localization of opiate receptor subtypes was carried out using Western blot and flow cytometry. The effect of opiate antagonist on granulosa cell VEGF secretion was assessed by enzyme-linked immunosorbent assay. For the first time, the presence of OPRM1 on human granulosa cells is reported. Blocking of opiate signalling using naloxone, a specific OPRM1 antagonist, significantly reduced granulosa cell-derived VEGF levels in both COV434 and granulosa-luteal cells (P < 0.01). The presence of opiate receptors and opiate signalling in granulosa cells suggest a possible role in VEGF production. Targeting this signalling pathway could prove promising as a new clinical option in the prevention and treatment of ovarian hyperstimulation syndrome.

Enhanced Intranasal Absorption of Naltrexone by Dodecyl Maltopyranoside: Implications for the Treatment of Opioid Overdose.

Based on its high affinity for µ opiate receptors and reported half-life after oral administration, the pharmacokinetic properties of intranasal naltrexone were examined to evaluate its potential to treat opioid overdose. This study was prompted by the marked rise in overdose deaths linked to synthetic opioids like fentanyl, which may require more potent, longer-lived opiate antagonists than naloxone. Both the maximum plasma concentration (Cmax ) and the time (Tmax ) to reach Cmax for intranasal naltrexone (4 mg) were comparable to values reported for a Food and Drug Administration-approved 4-mg dose of intranasal naloxone. The addition of the absorption enhancer dodecyl maltoside (Intravail) increased Cmax by ∼3-fold and reduced the Tmax from 0.5 to 0.17 hours. Despite these very rapid increases in plasma concentrations of naltrexone, its short half-life following intranasal administration (∼2.2 hours) could limit its usefulness as a rescue medication, particularly against longer-lived synthetic opioids. Nonetheless, the ability to rapidly attain high plasma concentrations of naltrexone may be useful in other indications, including an as-needed dosing strategy to treat alcohol use disorder.