The acute effects of multiple doses of methamphetamine on locomotor activity and anxiety-like behavior in adolescent and adult mice.

Methamphetamine (MA) is a highly addictive psychomotor stimulant drug. Research has shown that the acute effects of MA can be modulated by age, although previous findings from our lab do not find age differences in the effects of MA. Relatively little research has examined the effects of adolescent MA exposure; thus, it is important to understand how MA affects adolescent behavior and brain function compared to adults. In order to better understand the age differences in the effects of acute MA exposure, this research examined the effects of MA exposure on locomotor and anxiety-like behavior and plasma corticosterone levels in adolescent and adult C57BL/6 J mice. Mice were exposed to saline, 2 mg/kg MA, or 4 mg/kg MA and behavior was measured in the open field test. Immediately following behavioral testing, serum was collected, and plasma corticosterone levels were measured. MA-exposed mice showed increased locomotor activity and anxiety-like behavior compared to saline controls, regardless of age and dose of MA. However, adolescent mice showed the greatest locomotor response to the high dose of MA (4 mg/kg), whereas the adult mice showed the greatest locomotor response to the low dose of MA (2 mg/kg). There were no differences in stereotyped behavior between the adolescent and adult mice exposed to the low dose of MA (2 mg/kg) and the high dose of MA (4 mg/kg). There was no effect of MA exposure on plasma corticosterone levels. These data suggest age modulates the locomotor response to MA and further research is warranted to determine the developmental neurobiological mechanism underlying the dose-response age differences in the response to acute MA exposure.

The effect of methadone on the hypothalamic pituitary gonadal axis and sexual function: A systematic review.

BACKGROUND: Opioid abuse is a public health crisis. As opioid misuse worsens, efforts are being made to increase access to medication-assisted treatments. Methadone is a medication-assisted treatment used to treat opioid dependence and chronic pain. While methadone is beneficial in the treatment of opiate abuse and chronic pain, side effects of the medication include hormonal and sexual function changes. The purpose of this report is to review the effects of methadone on the hypothalamic pituitary gonadal axis hormones and sexual functioning in males and females. METHODS: A search of PubMed was conducted using pre-defined criteria, resulting in the evaluation of 295 articles. A total of 72 articles, including 52 human studies and 20 animal studies, met the selection criteria and were reviewed. The included studies examined the effects of methadone on the hypothalamic pituitary gonadal axis and/or sexual function. RESULTS: There was evidence of methadone-induced hormonal changes, disruptions in the hypothalamic pituitary gonadal axis, and sexual dysfunction, although there was some variability in the results of the reviewed studies. Differences in methadone dose and length of exposure to treatment appears to influence the variability in the results. Much of the literature examines the effects of methadone in males, with very limited research examining the effects in females. CONCLUSIONS: Despite its effectiveness for opiate abuse and chronic pain treatment, methadone has disruptive effects on the hypothalamic pituitary gonadal axis and sexual function. Further research is warranted to better define potential methadone-induced endocrine consequences and to further examine the effects of methadone in females.