Oxycodone hcl

The development of the IUO treatment paradigm was adapted from a previously published study [12 (link)]. Nulliparous female (64–70 days of age) Sprague Dawley rats were treated with oxycodone HCl (Sigma Aldrich, St. Louis, MO, USA) dissolved in saline or saline vehicle via oral gavage. An ascending dosing procedure was used wherein doses of 10 mg/kg/day oxy were orally gavaged for 5 days followed by 0.5 mg/kg/day escalation for 10 days to a final dose of 15 mg/kg/day, after which females were mated with proven male breeders, and the treatment regimen continued throughout mating, gestation, and parturition until weaning. Because the half-life of oxy is relatively short and drug distribution can be altered by pregnancy, dams were monitored daily for signs of opiate withdrawal, such as weight loss, diarrhea, and irritability, throughout gestation. For the PNO paradigm, dams were orally gavaged with 15 mg/kg/day of oxy after parturition until weaning. For the current study, brains from saline, IUO, and PNO offspring were harvested at postnatal day 14 (P14) and stored at –80 °C until subsequent use.

The treatment paradigm previously established in our lab was followed [11 (link),17 (link)]. Briefly, female (64–70 days of age) Sprague Dawley rats were treated with oxycodone HCl (Sigma Aldrich, St. Louis, MO, USA) dissolved in a saline vehicle via oral gavage. An ascending dosing procedure was used where doses of 10 mg/kg/day of oxy were orally-gavaged for 5 days followed by a 0.5 mg/kg/day escalation for 10 days until reaching a final dose of 15 mg/kg/day, after which females were mated with proven male breeders. The treatment regimen continued throughout mating, gestation, and parturition until weaning on post-natal day (P) 21. For the PNO paradigm, dams were orally-gavaged with 15 mg/kg/day of oxy only after parturition until weaning. The solo control group received no treatment in order to mimic a real-life scenario, i.e., normal drug-free mothers. For this study, offspring were sacrificed at P14, and brains were removed and stored at −80 °C.

29•oxalate was dissolved daily in sterile water vehicle for all pharmacodynamic studies. 29•oxalate was dissolved in saline (1 mg/mL) for pharmacokinetic studies and in methanol (0.84 mg/mL) for analytical stocks. The MOR agonist oxycodone HCl (Sigma-Aldrich) was dissolved in sterile water vehicle. All injections were carried out IP in a volume of 10 mL/kg body weight. The KOR agonist U50,488 (Sigma-Aldrich) was dissolved in sterile water. All injections for antinociception and locomotor studies were made by the IP route at a volume of 10 mL/kg body weight.

Doxycycline hyclate (Cayman Chemical, Ann Arbor, MI, USA) was made fresh daily to a dose of 30 mg/kg in sterile saline (0.9% w/v) and injected via intraperitoneal (i.p.) route once daily for 5 days. Oxycodone HCl (Sigma-Aldrich, St. Louis, MO, USA) was dissolved to a concentration of 3.0 mg/kg in sterile saline and injected i.p. 15 min prior to behavioral testing (see Figure 1A). The present dose of oxycodone (3.0 mg/kg) was identified as the minimum effective dose to diverge psychomotor responding between Tat(−) and Tat(+) mice [43 (link)]. To pharmacologically block CRF-receptors, mice were administered antalarmin (Cayman Chemical) dissolved in 30% Kolliphor (70% sterile saline) to a dose of 20.0 mg/kg (i.p) administered once daily for 7 days [42 (link),51 (link),52 (link)]. To block glucocorticoid receptors, mice were administered RU-486 (a.k.a. mifepristone; Cayman Chemical) dissolved in 30% Kolliphor, 1% DMSO and Tween 20 (3 drops) to a dose of 20 mg/kg (i.p.) administered once daily for 8 days [42 (link),53 (link),54 (link)].