D methamphetamine hydrochloride

Physiological saline (0.9% NaCl) and d-Methamphetamine hydrochloride were purchased from Sigma-Aldrich (Czech Republic). MA was injected subcutaneously at a 5 mg/ml/kg dose to rat pups (direct) or rat lactating mothers (indirect) during PND 1–12, and control SA rats were given the same volume of SA. Administration of substances was held during morning hours. This dose is dose commonly used in our laboratory since 2005, because it induces the concentration in the blood comparable to human studies [30 (link)].

Litters were divided into groups as shown in Table 1. One half of the offspring were treated indirectly via the breast milk of injected mothers, and the other half were treated directly by MA injection subcutaneously (s.c.). In the group with indirect exposure, mothers received MA (5 mg/ml/kg) or S (1 ml/kg) between PD 1–11. In the group with direct exposure none of the mothers were treated (i.e., no MA and no S). Instead, progeny were either: (1) treated with injected MA (5 mg/ml/kg); or (2) served as controls and received sham injections (no saline, just a needle stick) on PD 1–11. We used sham controls because our previous unpublished data showed that newborns injected with saline died at higher rates than MA injected pups.
The direct dose of MA for injection was chosen based on findings of MA levels seen in fetuses of drug-abusing women (Acuff-Smith et al., 1996 (link); Šlamberová et al., 2005 (link); Rambousek et al., 2014 (link)); additionally, MA exposure through maternal breast milk is similar in both rats and humans (Behnke and Smith, 2013 (link); Rambousek et al., 2014 (link)). Physiological saline solution (0.9% NaCl) and d-Methamphetamine hydrochloride were purchased from Sigma–Aldrich (Czech Republic).

Separate groups of PKO and WT rats were intraperitoneally (i.p.) injected with 2 mg/kg (free-base) of d-methamphetamine hydrochloride (Sigma-Aldrich, St. Louis, MO, USA) dissolved in sterile saline (0.9% NaCl). The gross motor activity of all the animals was assessed using the Opto-Varimex 4 AutoTrack open-field Plexiglass chamber (Columbus Instruments, Columbus, OH). At the beginning of each session, the animals were placed in the middle of the Plexiglass chamber, and their subsequent movement and position were recorded continuously. For each drug-naïve animal, motor activity was assessed during 30-min session. Activity of methamphetamine-treated rats was recorded for 100 min. Horizontal locomotor activity (distance travelled), and stereotypic movements (time spent) were calculated automatically from the raw beam-break data by the Opto-Varimex software.