No abstract

Different forms of anxiety-related behavior have been reported after a single drug use of many abused substances, however, less is known about how males and females are affected differently from exposure to various drugs. Furthermore, chronic prenatal methamphetamine (MA) exposure was shown to predispose the animal to an increased sensitivity to drugs administrated in adulthood. Using the Elevated plus-maze test (EPM), the first aim of the present study was to examine how male and female rats are affected by acute drug treatment with subcutaneously (s.c.) administrated (a) MA (1mg/kg); (b) drugs with a similar mechanism of action to MA: amphetamine (AMP, 1mg/kg), cocaine (COC, 5mg/kg), 3,4-methylenedioxymethamphetamine (MDMA, 5mg/kg); and (c) drugs with different mechanisms of action: morphine (MOR, 5mg/kg), and Δ 9-tetrahydrocannabinol (THC, 2mg/kg). The second aim was to determine if prenatally MA-exposed (5mg/kg) animals show an increased sensitivity to adult drug treatment. The parameters analyzed were divided into two categories: anxiety-related behavior and anxiety-unrelated/exploratory behavior. Our results showed in female rats a decreased percentage of the time spent in the closed arms (CA) after MA, and an increased percentage of the time spent in the open arms (OA) after MA, AMP, and COC treatment, indicating an anxiolytic-like effect. In females, MDMA and THC treatment increased the percentage of the time spent in the CA. An increased percentage of the time spent in the CA was also seen after MOR treatment in females as well as in males, indicating an anxiogenic-like effect. As far as the interaction between prenatal MA exposure and adult drug treatment is concerned, there was no effect found. In conclusion, it seems that: (a) in some cases female rats are more vulnerable to acute drug treatment, in terms of either anxiogenic- or anxiolytic-like effects; (b) prenatal MA exposure does not sensitize animals to the anxiety-related effects of any of the drugs.

Methamphetamine (METH) is a widespread illicit drug. If it is taken by pregnant women, it passes through the placenta and just as it affects the mother, it can impair the development of the offspring. The aim of our study was to identify candidates to investigate for changes in the gene expression in the specific regions of the brain associated with addiction to METH in rats. We examined the various areas of the central nervous system (striatum, hippocampus, prefrontal cortex) for signs of impairment in postnatal day 80 in experimental rats, whose mothers had been administered METH (5 mg/kg/day) during the entire gestation period. Changes in the gene expression at the mRNA level were determined by two techniques, microarray and real-time PCR. Results of two microarray trials were evaluated by LIMMA analysis. The first microarray trial detected either up-regulated or down-regulated expression of 2189 genes in the striatum; the second microarray trial detected either up-regulated or down-regulated expression of 1344 genes in the hippocampus of prenatally METH-exposed rats. We examined the expression of 10 genes using the real-time PCR technique. Differences in the gene expression were counted by the Mann–Whitney U -test. Significant changes were observed in the cocaine- and amphetamine-regulated transcript prepropeptide, tachykinin receptor 3, dopamine receptor D3 gene expression in the striatum regions, in the glucocorticoid nuclear receptor Nr3c1 gene expression in the prefrontal cortex and in the carboxylesterase 2 gene expression in the hippocampus of prenatally METH-exposed rats. The microarray technique also detected up-regulated expression of trace amine-associated receptor 7 h gene in the hippocampus of prenatally METH-exposed rats. We have identified susceptible genes; candidates for the study of an impairment related to methamphetamine addiction in the specific regions of the brain.

Since close relationship was shown between drug addiction and memory formation, the aim of the present study was to investigate the effects of interaction between prenatal methamphetamine (MA) exposure and MA treatment in adulthood on spatial and non-spatial memory and on the structure of the N-methyl-D-aspartate (NMDA) receptors in the hippocampus. Adult male rats prenatally exposed to MA (5 mg/kg) or saline were tested in adulthood. Non-spatial memory was examined in the Object Recognition Test (ORT) and spatial memory in the Object Location Test (OLT) and in the Memory Retention Test (MRT) conducted in the Morris Water Maze (MWM), respectively. Based on the type of the memory test animals were injected either acutely (ORT, OLT) or long-term (MWM) with MA (1 mg/kg). After each testing, animals were sacrificed and brains were removed. The hippocampus was then examined in Western Blot analysis for occurrence of different NMDA receptors’ subtypes. Our results demonstrated that prenatal MA exposure affects the development of the NMDA receptors in the hippocampus that might correspond with improvement of spatial memory tested in adulthood in the MWM. On the other hand, the effect of prenatal MA exposure on non-spatial memory examined in the ORT was the opposite. In addition, we showed that the effect of MA administration in adulthood on NMDA receptors is influenced by prenatal MA exposure, which seems to correlate with the spatial memory examined in the OLT.

No abstract