Effects of perinatal stress and drug abuse on maternal behavior and sensorimotor development of affected progeny

Sleep and circadian rhythm activity alterations during adolescence in a mouse model of neonatal fentanyl withdrawal syndrome

Fentanyl, a highly potent synthetic opioid, is a major contributor to the ongoing opioid epidemic. During adulthood, fentanyl is known to induce pronounced sleep and circadian disturbances during use and withdrawal. Children exposed to opioids in utero are likely to develop neonatal opioid withdrawal syndrome, and display sleep disturbances after birth. However, it is currently unknown how neonatal opioid withdrawal from fentanyl impacts sleep and circadian rhythms in mice later in life. To model neonatal opioid withdrawal syndrome, mice were treated with fentanyl from postnatal days 1 through 14, analogous to the third trimester of human gestation. After weaning, fentanyl and saline treated mice underwent non-invasive sleep and circadian rhythm monitoring during adolescence postnatal days 23 through 30. Neonatal fentanyl exposure led to an increase in the percent time spent in rapid eye movement sleep across days. Thus, neonatal fentanyl exposure leads to altered sleep-wake states during adolescence in mice.

Perinatal Stress and Methamphetamine Exposure Decreases Anxiety-Like Behavior in Adult Male Rats

Methamphetamine (MA) is an illicit synthetic psychostimulant drug, and its abuse is growing worldwide. MA has been reported as the primary drug of choice, by drug-abusing women, during pregnancy. Since MA easily crosses the placental barrier, the fetus is exposed to MA in a similar fashion to the mother. This study aimed to evaluate the effect of long-term perinatal stressors and drug exposure on anxiety-like behavior in adult male rats using the open field test (OF) and elevated plus maze (EPM). Dams were divided into three groups according to drug treatment during pregnancy: controls (C), saline-SA [subcutaneous (s.c.), 1 ml/kg], and MA (s.c., 5 mg/kg). Litters were divided into four groups according to postnatal stressors: non-stressed controls (N), maternal separation (S), maternal cold water stress (W), and maternal separation plus maternal cold water stress (SW). Forty-five minutes before testing (in both OF and EPM), one-half of adult male rats received an (s.c.) injection of MA and the other half received an SA injection. Prenatal MA/stress exposure did not affect anxiety-like behavior in adult male rats in both tests. In the OF, an acute MA dose in adulthood increased the time spent in the central disk area, decreased time spent in the corners, and decreased time spent immobile and grooming. Also, postnatal stress increased time spent in the central disk area, decreased time spent in corners, and increased mobility compared to controls. All groups of rats exposed to postnatal stressors spent significantly less time in the closed arms of the EPM compared to controls. Overall, our results indicate that early postnatal stress and a single acute MA administration in adulthood decreases the parameters of anxiety-like behavior in adult male rats regardless of prenatal MA exposure. Moreover, postnatal stress via maternal separation impacts the effect of acute MA administration in adulthood. Long-term postnatal stress may thus result in improved adaptation to subsequent stressful experiences later in life.

Short term methylphenidate treatment does not increase myocardial injury in the ischemic rat heart

Methylphenidate is commonly used for the treatment of attention deficit hyperactivity disorder. The cardiovascular safety of methylphenidate has been a subject of debate with some studies indicating that methylphenidate increases the likelihood of experiencing a myocardial infarction. However, it is unknown whether methylphenidate worsens the extent of injury during an ischemic insult. The purpose of this study was to determine whether short term exposure to methylphenidate increases the extent of myocardial injury during an ischemic insult. Male and female rats received methylphenidate (5 mg/kg/day) or saline for 10 days by oral gavage. Hearts were subjected to 20 min of ischemia and 2 h of reperfusion on a Langendorff isolated heart apparatus on day 11. Cardiac contractile function was monitored via an intraventricular balloon and myocardial injury was assessed by triphenyltetrazolium chloride staining. Methylphenidate significantly increased locomotor activity in male and female rats, confirming absorption of this psychostimulant into the central nervous system. Male hearts had significantly larger infarcts than female hearts, but methylphenidate had no impact on infarct size or postischemic recovery of contractile function in hearts of either sex. These data indicate that methylphenidate does not increase the extent of injury induced by an ischemic insult.

Influence of Prenatal Methamphetamine Abuse on the Brain

Methamphetamine (MA), a psychostimulant, has become a serious problem in recent years. It is one of the most widely abused psychostimulants in the world. In the Czech Republic, ecstasy is the most commonly used non-cannabis drug, followed by hallucinogenic fungi, LSD, MA, cocaine, and finally heroin. The prevalence of the usage of all addictive substances is highest in the age category of 15-34. Approximately 17.2% of registered drug addicts, both male and female, in the Czech Republic use MA as their first-choice drug. This group consists mostly of women who are unemployed and addicted to MA (85%). Almost half of the addicted women switched to MA from other drugs in the course of pregnancy. Psychostimulants such as amphetamine and its synthetic derivate MA induce feelings of calm and happiness by suppressing anxiety and depression. When MA is abused for longer periods, it mimics symptoms of mania and can lead to the development of psychosis. MA is often abused for its anorectic effect, its simple preparation, and compared to heroin and cocaine, its low price. There are significant differences in the susceptibility of users to the stimulant, with reactions to MA fluctuating from person to person. Molecular mechanisms related to the variable response among users might represent an explanation for increased addiction-associated bipolar disorder and psychosis. Currently, there is limited information regarding genetic mechanisms linked to these disorders and the transmission of drug addiction. As such, animal models of drug addiction represent significant sources of information and assets in the research of these issues. The aim of this review is to summarize the mechanism of action of methamphetamine and its effect on pregnant addicted women and their children, including a detailed description of the anatomical structures involved.

Methamphetamine exposure during the first, but not the second half of prenatal development, affects social play behavior

Methamphetamine (MA), as a psychostimulant drug that crosses the placental barrier, may disrupt the development of social play. The present study aims to examine the effect of prenatal MA (5 mg/kg) exposure during the first (gestational day (GD) 1-11) or second (GD 12-22) halves of prenatal development of rats on social play behavior. To investigate an acute effect of MA on social play in adulthood, juvenile rats were exposed to a dose of 1 mg/kg MA or saline on the test day and tested for social play for 15 min. Prenatal exposure to MA during GD 1-11 increased social play behavior during 5-10 min interval of the test in males but not females. Prenatal MA during GD 12-22 did not influence social play in males nor females. However, social play occurred to a greater extent in GD 12-22 groups compared with GD 1-11. Acute exposure to MA eliminated playful behavior in all groups and decreased social exploration in GD 1-11. Our results suggest that manipulation of prenatal development during the first half of the gestational period has a greater impact on social play behavior than during the second half.

Response of the maternal hypothalamus to cold stress during late pregnancy in rats

Maternal stress is a key risk factor in the development of offspring. We previously identified prenatal cold stress-induced anxiety-like behavior reduced in the offspring of rats along with negative feedback regulation from the maternal hippocampus on the hypothalamic-pituitary-adrenal (HPA) axis during prenatal cold stress. However, the precise function of the maternal hypothalamus response to cold stress during late pregnancy in rats has not yet been determined. Therefore, we examined proteins in the hypothalamus that respond to aldosterone, neurodevelopment, inflammation and apoptosis. Our results show that prenatal cold stress induced the expression of mineralocorticoid receptors (MR) and 11β-hydroxysteroid dehydrogenase type 2 (11β-HSD2), suggesting prenatal cold stress may promote the elevation of aldosterone levels in the hypothalamus. Remarkably, increased expression of brain derived neurotrophic factor (BDNF) helped to replenish intracellular peptidergic stores and ensure homeostatic balance during prenatal cold stress. Furthermore, prenatal cold stress reduced the expression of c-Fos via STAT3 and ERK1/2 pathways in the hypothalamus. Moreover, prenatal cold stress induced NF-κB phosphorylation at Ser536, then promoted the expression of inducible nitric oxide synthase (iNOS) and induced an apoptosis-related protein response. Together, this study confirms that changes in the maternal hypothalamus during cold stress in late pregnancy are directly reflective of the response of the HPA to cold stress and demonstrates how the hypothalamus coordinates cold stress. We suggest mechanisms which might explain how these states might be linked with an abnormal stress response.

What is the role of subcutaneous single injections on the behavior of adult male rats exposed to drugs?

Psychostimulants, as well as cannabinoids, have been shown to significantly affect a great variety of behaviors in both humans and laboratory animals. Our previous studies have repeatedly demonstrated that the application of the vehicle for psychostimulants, i.e. saline, to control groups, generated different behavioral test results compared to absolute naive controls (i.e. without any injection). Therefore, our present study has set three goals: (1) to evaluate the effect of three different psychostimulant drugs, (2) to evaluate the effect of three doses of delta 9-tetrahydrocannabinol (THC), and (3) to evaluate the effect of saline and ethanol injections vs sham injections and no injection on spontaneous behavior of adult male rats. The LABORAS test (Metris B.V., Netherlands) was used to examine spontaneous locomotor activity and exploratory behavior in an unknown environment over 1 h. In Experiment 1, psychostimulant drugs were tested: single subcutaneous (s.c.) injections of amphetamine (5 mg/kg), cocaine (5 mg/kg), and 3,4-methylenedioxymethamphetamine (MDMA) (5 mg/kg) were applied prior to testing. Control animals received the same volume (1 ml/kg) of s.c. saline. In Experiment 2, the effect of three doses of THC (1, 2, and 5 mg/kg, s.c.) were examined. An s.c. injection of vehicle (ethanol) was used as a control. In Experiment 3, injections of saline and ethanol were compared to the group receiving a sham s.c. injection and to a group of absolute "naive" controls. Our results demonstrated that (1) all psychostimulants increased locomotion time, distance traveled, and speed while decreasing immobility time of adult male rats relative to saline controls. The most prominent effect was associated with MDMA; (2) The effect of THC was dose-dependent and was most apparent within the first 10 min of the LABORAS test. (3) With regard to the effect of injection: absolute controls (without injection) compared to animals injected with ethanol, saline, or sham-injected displayed reduced immobility time, traveled longer distances, and had increased speed. In conclusion, our data showed drug dependent behavioral changes in adult male rats after application of psychostimulants and cannabinoids. Our findings also suggest that not only drugs but the actual single injection per se also affects the behavior of laboratory animals in an unknown environment. This effect seems to be associated with the acute stress associated with the injection.

Early Postnatal Stress Impairs Cognitive Functions of Male Rats Persisting Until Adulthood

Methamphetamine (MA) is the most abused “hard” illicit drug in the Czech Republic. Drugs abused during pregnancy are not hazardous merely to the mother, but also to developing fetuses. The offspring of drug-addicted mothers are also often exposed to perinatal stressors that may impair brain development of affected progeny. The present study examines the effect of perinatal stressors and drug exposure on cognitive function in male progeny. In the present study, rat mothers were divided into three groups according to drug treatment during pregnancy: controls (C); saline (SA, s.c., 1 ml/kg); MA (s.c., 5 mg/ml/kg). Litters were divided into two groups according to postnatal stressors: non-stressed controls (N); Maternal separation (MS). For evaluation of learning and memory, adult male progeny were tested in the Morris Water Maze (MWM). Our results revealed no significant effects caused by prenatal drug or prenatal stress exposure. On the other hand, chronic postnatal stress, mediated by MS, significantly impaired learning on the Place Navigation test. In addition, MS was associated with changes in search strategies on the Place Navigation, Probe, and Memory Recall tests. Specifically, postnatal stress increased thigmotaxis, indicating less awareness of the hidden platform. In conclusion, the present study provides evidence that exposure to early postnatal stress significantly impairs cognitive functions of male rats, which persists into adulthood.

Does effect from developmental methamphetamine exposure on spatial learning and memory depend on stage of neuroontogeny?

Psychostimulants, including methamphetamine (MA), have neurotoxic effect, especially, if they are targeting CNS during its critical periods of development. The present study was aimed to examine cognitive changes after prenatal and neonatal MA treatment in combination with chronic MA exposure in adulthood of male rats. Eight groups of male rats were tested in adulthood: males whose mothers were exposed to MA (5 mg/kg) or saline (SA, 1 ml/kg) during the first half of gestation period (GD 1-11), the second half of gestation period (GD 12-22) and neonatal period (PD 1-11). In addition, we compared indirect neonatal application via the breast milk with the group of rat pups that received MA or SA directly by injection (PD 1-11). Males were tested in adulthood for cognitive changes in the Morris Water Maze (MWM). MWM experiment lasted for 12 days: Learning (Day 1-6), Probe test (Day 8) and Retrieval Memory test (Day 12). Each day of the MWM animals were injected with MA (1 mg/kg) or SA (1 ml/kg). Prenatal MA exposure did not induce changes in learning abilities of male rats, but neonatal exposure to MA leads to an increase search errors and latencies to find the hidden platform. Prenatal and also neonatal MA exposure impaired cognitive ability to remember the position of the platform in Retrieval Memory test in adulthood. Animals exposed to the prenatal treatment within the second half of gestation (ED 12-22) swam longer, slower and spent more time to find the hidden platform in Retrieval Memory test than animals exposed throughout other periods. The present study demonstrated that stage of development is crucial for determination the cognitive deficits induced by prenatal or neonatal MA exposure.