In recent years methamphetamine (MA) use has become more prevalent, and of particular concern is its growing popularity of MA among women of childbearing age. However, to date, studies examining MA effects on the developing offspring in laboratory animals are limited. Thus, the aim of this study was to determine if in utero MA exposure in rats at pharmacological doses can have a negative impact on neonatal neurodevelopment and behaviour. Pregnant Sprague-Dawley dams (n=10 dams/group) received MA (0, 0.625, 1.25, 2.5mg/kg) once daily via oral gavage from gestational day 7 to 21. Maternal body weight, food and water consumption were recorded daily. A range of standard neurodevelopment parameters was examined in the offspring during the neonatal period. There were no neurodevelopmental deficits observed with offspring exposed to 0.625mg/kg MA, in fact, there were enhancements of neurodevelopment in some parameters at this low dose. However, exposure to the 1.25mg/kg MA dose resulted in significant impairments in surface righting reflex and forelimb grip in both sexes. Exposure to the 2.5mg/kg MA dose resulted in a significant reduction in ano-genital distance in males, and in both sexes resulted in delayed fur appearance and eye opening, impairments in surface righting reflex and negative geotaxis, and a reduction in body length. In conclusion, this study demonstrates that pharmacologically relevant doses of MA can have profound dose-related effects on neonatal outcome. If extrapolated to the clinical scenario this will give cause for concern regarding the risks associated with this drug of abuse at relatively low doses.
BackgroundThe prevalence of methamphetamine (MA) use has increased in recent years. In order to assess how this drug produces its effects, both clinical and preclinical studies have recently begun to focus on oxidative stress as an important biochemical mechanism in mediating these effects.ObjectiveThe purpose of this review is to illustrate the variation in the design of preclinical studies investigating MA exposure on oxidative stress parameters in animal models.MethodThe experimental variables investigated and summarised include MA drug treatment, measurements of oxidative stress and antioxidant treatments that ameliorate the harmful effects of MA.ResultsThese preclinical studies differ greatly in their experimental design with respect to the dose of MA (ranging between 0.25 and 20 mg/kg), the dosing regime (acute, binge or chronic), the time of measurement of oxidative stress (0.5 h to 2 wks after last MA administration), the antioxidant system targeted and finally the use of antioxidants including the route of administration (i.p. or p.o.), the frequency of exposure and the time of exposure (preventative or therapeutic).ConclusionThe findings in this paper suggest that there is a large diversity among these studies and so the interpretation of these results is challenging. For this reason, the development of guidelines and how best to assess oxidative stress in animal models may be beneficial. The use of these simple recommendations mean that results will be more comparable between laboratories and that future results generated will give us a greater understanding of the contribution of this important biochemical mechanism and its implications for the clinical scenario.
Methamphetamine (MA) has become a popular drug of abuse in recent years not only in the general population but also amongst pregnant women. Although there is a growing body of preclinical investigations of MA exposure during pregnancy, there has been little investigation of the consequences of such exposure via the breast milk during the neonatal period. Therefore, the aim of this study was to determine the consequences of MA exposure during pregnancy and lactation on neurodevelopment and behaviour in the rat offspring. Pregnant Sprague-Dawley dams received MA (3.75 mg/kg) or control (distilled water) once daily via oral gavage from gestation day 7-21, postnatal day 1-21 or gestation day 7- postnatal day 21. A range of well-recognised neurodevelopmental parameters were examined in the offspring. Prenatal MA significantly reduced maternal weight gain, with a concomitant reduction in food intake. A significant increase in neonatal pup mortality was observed, being most marked in the prenatal/postnatal MA group. Significant impairments in neurodevelopmental parameters were also evident in all MA treatment groups including somatic development (e.g. pinna unfolding, fur appearance, eye opening) and behavioural development (e.g. surface righting, inclined plane test, forelimb grip). In conclusion, this study demonstrates that exposure to MA during any of these exposure periods (prenatal and/or postnatal) can have a profound effect on neonatal outcome, suggesting that regardless of the exposure period MA is associated with detrimental consequences in the offspring. These results indicate that in the clinical scenario, exposure during lactation needs to be considered when assessing the potential harmful effects of MA on offspring development.
Many preclinical studies have aimed to elucidate the effects of methamphetamine (MA) exposure during pregnancy on the offspring in recent years. However, the severity of effects on the neonate may be related to the subcutaneous (sc) route of administration of the drug that is often employed (88% of preclinical studies) and consequently the delivered dose that the foetus is exposed to. To date there is a paucity of comparative studies investigating different routes of administration for MA during pregnancy and it is not known how these different routes compare when it comes to neonatal outcome. Thus, the aim of this study was to determine if the route of administration of MA (oral gavage or sc injection) during pregnancy at a pharmacological dose affects the magnitude of neurodevelopmental and behavioural effects in the resultant rat offspring. Pregnant Sprague-Dawley dams (n=10 dams/group) received MA (3.75 mg/kg) or control (distilled water) via oral gavage or sc injection from gestation day 7-21. A range of well-recognised neurodevelopmental parameters were examined in the offspring. When administered sc, MA significantly reduced maternal weight gain and altered maternal behaviour; mothers spent less time in the nest with pups and spent less time nursing compared to controls. Significant impairments in neurodevelopmental parameters were evident in both MA treatment groups. Somatic development such as pinna unfolding, fur appearance and eye opening were all delayed after MA exposure but these impairments were more pronounced in the MA sc group. Other somatic parameters such as ano-genital distance and body length were only impeded by sc MA. Behavioural development in the surface righting, inclined plane and forelimb grip tests were also altered for both MA treatment groups. This study demonstrates that prenatal MA can have a profound effect on neonatal outcome, but this can be exacerbated if given via the subcutaneous route, as well as producing additional effects not seen with the oral gavage route. Consequently, the route of administration should be considered when interpreting preclinical studies investigating prenatal MA exposure.
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