The effect of early environmental manipulation on locomotor sensitivity and methamphetamine conditioned place preference reward

Abstract

Early life stress leads to several effects on neurological development, affecting health and well-being later in life. Instances of child abuse and neglect are associated with higher rates of depression, risk taking behavior, and an increased risk of drug abuse later in life. This study used repeated neonatal separation of rat pups as a model of early life stress. Rat pups were either handled and weighed as controls or separated for 180 minutes per day during postnatal days 2-8. In adulthood, male and female rats were tested for methamphetamine conditioned place preference reward and methamphetamine induced locomotor activity. Tissue samples were collected and mRNA was quantified for the norepinephrine transporter in the prefrontal cortex and the dopamine transporter in the nucleus accumbens. Results indicated rats given methamphetamine formed a conditioned place preference, but there was no effect of early separation or sex. Separated males showed heightened methamphetamine-induced locomotor activity, but there was no effect of early separation for females. Overall females were more active than males in response to both saline and methamphetamine. No differences in mRNA levels were observed across any conditions. These results suggest early neonatal separation affects methamphetamine-induced locomotor activity in a sex-dependent manner but has no effects on methamphetamine conditioned place preference.

Chronic variable stress and intravenous methamphetamine self-administration – Role of individual differences in behavioral and physiological reactivity to novelty

“…Our current findings show no effect of CVS on methamphetamine CPP in adults and are consistent with studies indicating that early life stress does not influence (Faure et al, 2009, Hensleigh and Pritchard, 2014) or even attenuate (Dimatelis et al, 2012) methamphetamine CPP. Our findings also confirm those of others in adult male Sprague Dawley rats, such that 0.06 mg/kg methamphetamine is a subthreshold dose for the development of methamphetamine CPP (Zakharova et al, 2009).…”

Maternal separation increases methamphetamine-induced damage in the striatum in male, but not female rats

“…Maternally separated males also show enhanced rewarding effects of opiates, cocaine, and amphetamine [18], [19], [20], and [21]. Further, maternal separation may [22] or may not [23] and [24] enhance methamphetamine reward sensitivity, depending on the behavioral measure used. However, separated animals acquire cocaine and methamphetamine administration more quickly relative to controls [21] and [22].…”

Effects of early life stress on biochemical indicators of the dopaminergic system: a 3 level meta-analysis of rodent studies

“…W. Fan et al 2011; L.-W. Fan et al 2011; Gerardin et al 2005; Gondré-Lewis et al 2015; Gracia-Rubio et al 2016; Granholm et al 2011; Hall et al 1999; Emily Hensleigh and Pritchard 2015; E. Hensleigh and Pritchard 2014; Hermel et al 2001; Hill et al 2014; J.…”