Antineoplastics for treating Alzheimer's disease and dementia: Evidence from preclinical and observational studies

As the world population ages, there will be an increasing need for effective therapies for aging-associated neurodegenerative disorders, which remain untreatable. Dementia due to Alzheimer's disease (AD) is one of the leading neurological diseases in the aging population. Current therapeutic approaches to treat this disorder are solely symptomatic, making the need for new molecular entities acting on the causes of the disease extremely urgent. One of the potential solutions is to use compounds that are already in the market. The structures have known pharmacokinetics, pharmacodynamics, toxicity profiles, and patient data available in several countries. Several drugs have been used successfully to treat diseases different from their original purposes, such as autoimmunity and peripheral inflammation. Herein, we divulge the repurposing of drugs in the area of neurodegenerative diseases, focusing on the therapeutic potential of antineoplastics to treat dementia due to AD and dementia. We briefly touch upon the shared pathological mechanism between AD and cancer and drug repurposing strategies, with a focus on artificial intelligence. Next, we bring out the current status of research on the development of drugs, provide supporting evidence from retrospective, clinical, and preclinical studies on antineoplastic use, and bring in new areas, such as repurposing drugs for the prion-like spreading of pathologies in treating AD.

Triazole-based estradiol dimers prepared via CuAAC from 17α-ethinyl estradiol with five-atom linkers causing G2/M arrest and tubulin inhibition

Microtubule dynamic is exceptionally sensitive to modulation by small-molecule ligands. Our previous work presented the preparation of microtubule-targeting estradiol dimer (ED) with anticancer activity. In the present study, we explore the effect of selected linkers on the biological activity of the dimer. The linkers were designed as five-atom chains with carbon, nitrogen or oxygen in their centre. In addition, the central nitrogen was modified by a benzyl group with hydroxy or methoxy substituents and one derivative possessed an extended linker length. Thirteen new dimers were subjected to cytotoxicity assay and cell cycle profiling. Dimers containing linker with benzyl moiety substituted with one or more methoxy groups and longer branched ones were found inactive, whereas other structures had comparable efficacy as the original ED (e.g. D1 with IC₅₀ = 1.53 µM). Cell cycle analysis and immunofluorescence proved the interference of dimers with microtubule assembly and mitosis. The proposed in silico model and calculated binding free energy by the MM-PBSA method were closely correlated with in vitro tubulin assembly assay.

Potential neuroprotective and anti-apoptotic properties of a long-lasting stable analog of ghrelin: an in vitro study using SH-SY5Y cells

Neurodegenerative disorders, such as Alzheimer's disease (AD) and Parkinson's disease (PD), are increasing in prevalence. Currently, there are no effective and specific treatments for these disorders. Recently, positive effects of the orexigenic hormone ghrelin on memory and learning were demonstrated in mouse models of AD and PD. In this study, we tested the potential neuroprotective properties of a stable and long-lasting ghrelin analog, Dpr(3)ghrelin (Dpr(3)ghr), in SH-SY5Y neuroblastoma cells stressed with 1.2 mM methylglyoxal (MG), a toxic endogenous by-product of glycolysis, and we examined the impact of Dpr(3)ghr on apoptosis. Pre-treatment with both 10(-5) and 10(-7) M Dpr(3)ghr resulted in increased viability in SH-SY5Y cells (determined by MTT staining), as well as reduced cytotoxicity of MG in these cells (determined by LDH assay). Dpr(3)ghr increased viability by altering pro-apoptotic and viability markers: Bax was decreased, Bcl-2 was increased, and the Bax/Bcl-2 ratio was attenuated. The ghrelin receptor GHS-R1 and Dpr(3)ghr-induced activation of PBK/Akt were immuno-detected in SH-SY5Y cells to demonstrate the presence of GHS-R1 and GHS-R1 activation, respectively. We demonstrated that Dpr(3)ghr protected SH-SY5Y cells against MG-induced neurotoxicity and apoptosis. Our data suggest that stable ghrelin analogs may be candidates for the effective treatment of neurodegenerative disorders.

Prenatal methamphetamine exposure induces long-lasting alterations in memory and development of NMDA receptors in the hippocampus

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.

Does Prenatal Methamphetamine Exposure Induce Cross-sensitization to Cocaine and Morphine in Adult Male Rats?

The aim of the present study was to examine the cross-sensitization induced by prenatal methamphetamine (MA) exposure to challenge dose of cocaine or morphine. Rat mothers received a daily injection of MA (5 mg/kg) or saline throughout the gestation period. Adult male offspring (prenatally MA- or saline-exposed) were divided to groups with challenge doses of saline (1 ml/kg), cocaine (5 mg/kg) or morphine (5 mg/kg). Behavior in unknown environment was examined in Laboras, nociception in Plantar test, and active drug-seeking behavior in conditioned place preference (CPP). Our data demonstrate that cocaine increased the exploratory activity in Laboras test in prenatally saline-exposed, but decreased it in prenatally MA-exposed rats. An analgesic effect of cocaine was demonstrated only by the tail withdrawal and it was independent of the prenatal drug exposure. CPP test showed that prenatal MA exposure induced rather tolerance than sensitization to cocaine. In contrast to cocaine effects, morphine decreased rearing activity in both, prenatally MA-exposed and saline-exposed rats, and locomotion only in prenatally MA-exposed rats in the Laboras. In the Plantar test, the results demonstrated that morphine had an analgesic effect in prenatally saline-exposed rats but this effect was suppressed in prenatally MA-exposed rats. In the CPP test morphine induced drug-seeking behavior, which however was not affected by prenatal drug exposure. Thus, our data demonstrate that there is a cross-effect between prenatal MA exposure and the challenge dose of other drug in adulthood, however drug-seeking behavior is not increased by prenatal MA exposure as we expected.

Gender differences in the effect of prenatal methamphetamine exposure and challenge dose of other drugs on behavior of adult rats

The aim of the present study was to compare the response to acute application of several drugs in adult male and female rats prenatally exposed to methamphetamine (MA). Spontaneous locomotor activity and exploratory behavior of adult male and female rats prenatally exposed to MA (5 mg/kg) or saline were tested in a Laboras apparatus (Metris B.V., Netherlands) for 1 h. Challenge dose of the examined drug [amphetamine - 5 mg/kg; cocaine - 5 mg/kg; MDMA (3,4-methylenedioxymethamphetamine) - 5 mg/kg; morphine - 5 mg/kg; THC (delta9-tetrahydrocannabinol) - 2 mg/kg] or saline was injected prior to testing. Our data demonstrate that prenatal MA exposure did not affect behavior in male rats with cocaine or morphine treatment, but increased locomotion and exploration in females. Application of amphetamine and MDMA in adulthood increased activity in both sexes, while cocaine and THC only in female rats. Morphine, on the other hand, decreased the activity in the Laboras test in both sexes. As far as sex and estrous cycle is concerned, the present study shows that males were generally less active than females and also females in proestrus-estrus phase of the estrous cycle were more active than females in diestrus. In conclusion, the present study shows that the prenatal MA exposure does not induce general sensitization but affects the sensitivity to drugs dependently to mechanism of drug action and with respect to gonadal hormones.

Do prenatally methamphetamine-exposed adult male rats display general predisposition to drug abuse in the conditioned place preference test?

Drug abuse of pregnant women is a growing problem. The effect of prenatal drug exposure may have devastating effect on development of the offsprings that may be long-term or even permanent. One of the most common drug abused by pregnant women is methamphetamine (MA), which is also the most frequently abused illicit drug in the Czech Republic. Our previous studies demonstrated that prenatal MA exposure alters behavior, cognition, pain and seizures in adult rats in sex-specific manner. Our most recent studies demonstrate that prenatal MA exposure makes adult rats more sensitive to acute injection of the same or related drugs than their controls. The aim of the present study was to examine the effect of prenatal MA exposure on drug-seeking behavior of adult male rats tested in the Conditioned place preference (CPP). Adult male rats were divided to: prenatally MA-exposed (5 mg/kg daily for the entire prenatal period), prenatally saline-exposed (1 ml/kg of physiological saline) and controls (without maternal injections). The following drugs were used in the CPP test in adulthood: MA (5 mg/kg), amphetamine (5 mg/kg), cocaine (5 and 10 mg/kg), morphine (5 mg/kg), MDMA (5 mg/kg) and THC (2 mg/kg). Our data demonstrated that prenatally MA-exposed rats displayed higher amphetamine-seeking behavior than both controls. MA as well as morphine induced drug-seeking behavior of adult male rats, however this effect did not differ based on the prenatal MA exposure. In contrast, prenatal MA exposure induced rather tolerance to cocaine than sensitization after the conditioning in the CPP. MDMA and THC did not induce significant effects. Even though the present data did not fully confirmed our hypotheses, future studies are planned to test the drug-seeking behavior also in self-administration test.

Gender differences in behavioral changes elicited by prenatal methamphetamine exposure and application of the same drug in adulthood

The aim of the present study was to compare the response to sub-chronic application of methamphetamine (MA) in adulthood in male and female rats prenatally exposed to the same drug. The spontaneous locomotor activity and exploratory behavior of adult male and female rats prenatally exposed to 5 mg/kg MA or saline (SAL) were tested in a Laboras apparatus (Metris B.V., Netherlands) for five consecutive days, 1 hr daily. MA 1 mg/kg or SAL were used as a challenge prior to testing. Our results showed that rats prenatally exposed to MA were more sensitive to sub-chronic administration of MA in adulthood than prenatally SAL-exposed rats. However, this sensitizing effect of prenatal MA exposure was manifested differently in males and females. In contrast, prenatal MA exposure decreased baseline locomotion in females. This study indicates that gender plays an important role in the sensitivity to MA during prenatal development and in adulthood.

Sex differences in anxiety-like behavior and locomotor activity following prenatal and postnatal methamphetamine exposure in adult rats

The aim of the present study was to investigate the impact of prenatal and postnatal methamphetamine (MA) exposure on behavior and anxiety in adult male and female rats. Mothers were daily exposed to injection of MA (5 mg/kg) or saline (S): prior to impregnation and throughout gestation and lactation periods. On postnatal day 1, pups were cross-fostered so that each mother raised 6 saline-exposed pups and 6 MA-exposed pups. Based on the prenatal and postnatal exposure 4 experimental groups (S/S, S/MA, MA/S, MA/MA) were tested in the Open field (OF) and in the Elevated plus maze (EPM) in adulthood. Locomotion, exploration, immobility and comforting behavior were evaluated in the OF, while anxiety was assessed in the EPM. While prenatal MA exposure did not affect behavior and anxiety in adulthood, postnatal MA exposure (i.e. MA administration to lactating mothers) induced long-term changes. Specifically, adult female rats in diestrus and adult males postnatally exposed to MA via breast milk (S/MA and MA/MA) had decreased locomotion and exploratory behavior in the OF and showed increased anxiety-like behavior in the EPM when compared to female rats in diestrus or males postnatally exposed to saline (S/S and MA/S). In adult females in proestrus, postnatal exposure to MA affected only exploratory behavior in the OF when compared to rats in proestrus postnatally exposed to saline. Thus, the present study shows that postnatal exposure to MA via breast milk impairs behavior in unfamiliar environment and anxiety-like behavior of adult male and female rats more than prenatal MA exposure.

Impact of prenatal methamphetamine exposure on the sensitivity to the same drug in adult male rats

There are only few studies that examine the effect of prenatal methamphetamine (MA) exposure on the sensitivity to the same drug and the drug-seeking behavior in adulthood. The aim of the present study was to examine the effect of prenatal MA exposure on exploratory behavior and nociception with respect to challenge dose of the same drug. Mothers of the tested offspring received a daily injection of MA (5 mg/kg) or saline throughout the gestation period. Adult male offspring (prenatally MA- or saline-exposed) were divided to groups with challenge dose of MA (1 mg/kg) or saline. A modified Open field test (Laboras) was used to examine behavior in unknown environment. Plantar test was used to measure nociception on forelimbs, hind limbs, and the tail. Conditioned place preference (CPP) test was used to examine drug-seeking behavior. Our results in Laboras demonstrated that prenatal MA exposure sensitized the animals to the challenge dose of MA. Specifically prenatally MA-exposed animals that received the challenge MA in adulthood displayed higher locomotion and rearing activity relative to all the other groups. The Plantar test data suggest analgesic effect of MA (1 mg/kg), which however, did not differ based on the prenatal drug exposure. The results of CPP test showed that MA (5 mg/kg) conditioning resulted in increased drug-seeking behavior, but this effect was not affected by prenatal drug exposure. Thus, our data demonstrate that the effects of prenatal MA exposure and the challenge dose of the same drug in adulthood depend on behavioral model used.

Increased seizure susceptibility induced by prenatal methamphetamine exposure in adult female rats is not affected by early postnatal cross-fostering

Our previous studies repeatedly demonstrated that prenatal methamphetamine (MA) exposure alters seizure susceptibility in adult rats. Both the inhibitory GABA system and the excitatory NMDA system play a role in the effect of MA on epileptic seizures. On the basis of our previous behavioral results, the effect of cross-fostering on seizure susceptibility in adult female rats was examined in the present study. Bicuculline (GABA(A) receptor antagonist) and NMDA (NMDA receptor agonist) were used to induce seizures in adult female offspring exposed to MA in the prenatal and/or preweaning periods. Female dams were injected with MA (5mg/kg daily) or physiological saline (S) for approximately 9 weeks [about 3 weeks prior to impregnation, for the entire gestation period (22 days), and in the preweaning period (21 days)]. Absolute controls (C) did not receive any injections. On postnatal day 1, pups were cross-fostered so that each mother received pups from all three treatments. Thus, nine groups (based on the prenatal and postnatal drug exposures) of adult female rats were tested in each seizure test: C/C, C/S, C/MA, S/C, S/S, S/MA, MA/C, MA/S, MA/MA. The present study demonstrated that both the excitatory NMDA system and the inhibitory GABA system are involved in the proconvulsive effect of MA during prenatal and partially also postnatal development in female rats. However, because our results did not show any improvement in seizure susceptibility in prenatally MA-exposed animals that were fostered by control mothers (MA/C) relative to their siblings fostered by MA-treated mothers (MA/MA), our hypothesis of the cross-fostering effect seems to be incorrect in contrast to our behavioral studies.

Effect of cross-fostering on seizures in adult male offspring of methamphetamine-treated rat mothers

Stimulant drugs are often associated with increased seizure susceptibility. Inhibitory gamma-aminobutyric acid (GABA) and excitatory N-methyl-D-aspartate (NMDA) systems play a role in the effect of stimulants in the genesis of epileptic seizures. Our previous studies showed that prenatal methamphetamine (MA) exposure induced long-term changes in seizure susceptibility. The aim of the present study was to investigate the effect of cross-fostering on the prenatal and postnatal MA-exposed rats, respectively, on their seizures in adulthood. Bicuculline (GABA(A) receptor antagonist), NMDA (NMDA receptor agonist) and flurothyl (a convulsant gas) were used to induce seizures in adult male offsprings. Female dams were injected with MA (5 mg/kg daily) or physiological saline (S) for approx. 9 week [about 3 week prior to impregnation, for the entire gestation period (22 days) and in preweaning period (21 days)]. Absolute controls (C) did not receive any injections. On postnatal day 1, pups were cross-fostered so that each mother received pups from all three treatments. Thus, nine groups (based on the prenatal and postnatal drug exposure) of adult male rats were tested in each seizure test: C/C; C/S; C/MA; S/C; S/S; S/MA; MA/C; MA/S; MA/MA. The present study demonstrates that the effect of prenatal and/or postnatal MA exposure is seizure model specific. In addition, our data show that there is an effect of cross-fostering on seizures; particularly, the effect of prenatal MA exposure shown in animals fostered by control mothers is no longer apparent in animals fostered postnatally by MA-treated mothers. Such effect of postnatal treatment is not manifested in prenatal controls. In summary, it seems that: (1) prenatal MA exposure alters seizure susceptibility more than postnatal MA exposure; (2) especially in seizures induced by chemicals that affect GABAergic system (bicuculline, flurothyl) notable effect of adoption (cross-fostering) is apparent; (3) in seizure models that are associated with NMDA system (NMDA, flurothyl), effect of prenatal stress seems to play a role.

Effect of prenatal and postnatal methamphetamine exposure on nociception in adult female rats

The aim of the present study was to determine effects of methamphetamine (MA) exposure and cross-fostering on thermal nociceptive thresholds in different estrous phases in adult female rats. Rat mothers were exposed daily to injection of MA (5 mg/kg) or saline for 9 weeks: prior to impregnation, throughout gestation and lactation periods. Dams without any injections were used as an absolute control. On postnatal day 1, pups were cross-fostered so that each mother raised four pups of her own and eight pups from the mothers with the other two treatments. Offspring females were tested in adulthood (85-90 days) for thermal nociception as latency [s] of withdrawal reaction of forelimbs, hind limbs, and tail. Our results showed that prenatal MA exposure did not affect the nociception in adulthood, while postnatal MA exposure (i.e., MA administration to lactating mothers) had pro-nociceptive effects. The effect of postnatal MA exposure was apparent in both, fore- and hind limbs, while the latency to tail withdrawal reaction was the same among the groups. In addition, the pro-nociceptive effect of postnatal MA exposure did not depend on estrous cycle. This study indicates that postnatal but not prenatal exposure to MA affects nociception in adult female rats. However, it is still not clear whether the pro-nociceptive effect of postnatal MA exposure is linked to direct action of MA on neuronal organization, or to indirect action of MA mediated by impaired maternal care.

Effect of methamphetamine exposure and cross-fostering on cognitive function in adult male rats

The aim of our study was to examine the effect of prenatal methamphetamine (MA) exposure and cross-fostering on cognitive functions of adult male rats tested in Morris water maze (MWM). Rat mothers were exposed daily to injection of MA (5mg/kg) or saline for 9 weeks: prior to impregnation, throughout gestation and lactation periods. Females without any injections were used as an absolute control. On postnatal day 1, pups were cross-fostered so that each mother raised 4 pups of her own and 8 pups from the mothers with the other two treatments. Four types of tests were used: (1) Place navigation test (Learning), (2) Probe test (Probe), (3) Retention memory test (Memory) and (4) Visible platform task. Our results demonstrate that the prenatal exposure to MA does not impact learning and memory, while postnatal exposure to MA shows impairments in cognition. In the test of learning, all animals fostered to MA-treated dams had longer latencies, bigger search error and used lower spatial strategies than the animals fostered to control or saline-treated mother, regardless of prenatal exposure. Regardless of postnatal exposure, the animals prenatally exposed to saline swam faster in all the tests than the animals prenatally exposed to MA and controls, respectively. This study indicates that postnatal but not prenatal exposure to MA affects learning in adult male rats. However, it is still not clear whether these impairments are due to a direct effect of MA on neuronal structure or due to an indirect effect of MA mediated by impaired maternal care.

Egg sac silk of Theridiosoma gemmosum (Araneae: Theridiosomatidae)

Cocoons of Theridiosoma gemmosum consist of two main parts, the egg sac case and the stalk. The inner space of the egg sac case is filled with nonsticky flocculent silk. Measuring 600-800 nm in diameter, the flocculent threads are never made up of bundles of longitudinally oriented nanofibrils. The egg case wall consists of a lower layer of highly ordered threads and an upper layer of cover silk. The lower, permanently white layer consists of threads in a mesh-like arrangement, the thicker threads being 4-6 microm and the thinner threads being 2-3 microm in diameter. Each thread is a bundle of parallel nanofibrils, with a diameter between 150 and 300 nm. The silk secretions of these fibers, emitted from spigots, are processed by legs. The upper layer of the egg case is applied to the threads of the lower layer by direct rubbing against its surface, i.e. without the use of legs. In the lower and middle part of the egg case, the accumulated secretion forms a virtually compact encrustation, whereas in the upper, conically shaped, part of the egg case where it becomes the stalk, this secretion becomes substantially scarcer. The stalk is a continuation of the egg case, its proximal part made of fibers similar to those forming the inner layer of the egg case wall. The distal part of the stalk continues towards the suspension area either as a compact bundle of parallel fibers, or the stalk forks into two bundles of roughly the same thickness, which continue towards the suspension area separately. On the surface of objects onto which cocoons are attached, the secretion of the piriform glands acts as an adhesive sheet.

Does cross-fostering modify the prenatal effect of methamphetamine on learning of adult male rats?

Our previous studies demonstrated that methamphetamine administered during gestation and lactation periods impairs maternal behavior, alters the functional development of rat pups and affects behavior in adulthood. The aim of our study was to investigate the effect of prenatal methamphetamine exposure and cross-fostering on learning tested in Morris water maze (MWM) in adult male rats. Mothers were daily exposed to injection of methamphetamine (MA) (5 mg/kg) or saline (S): prior to impregnation and throughout gestation and lactation periods. On postnatal day 1, pups were cross-fostered so that each mother received some of her own and some of the pups of mother with the opposite treatment. Based on the prenatal and postnatal treatments 4 experimental groups (S/S, S/MA, MA/S, MA/MA) were tested in MWM. Two types of tests were used: (1) "Place navigation test" (Learning) and (2) "Probe test" (Probe). In the test of learning, all animals fostered by methamphetamine-treated dams had longer latencies and trajectories, and bigger search error than the animals fostered by saline-treated control mother, regardless of prenatal exposure. Further, the animals prenatally exposed to methamphetamine swam slower than the animals prenatally exposed to saline, regardless of postnatal exposure in the test of learning and in the Probe test. Our results showed that neither prenatal nor postnatal methamphetamine exposure affected the Probe test. Our results showed that prenatal exposure to methamphetamine at dose of 5 mg/kg does not impair learning in the MWM, while postnatal exposure to methamphetamine from mothers' breastmilk and maternal care of mother exposed to methamphetamine impairs learning of adult male rats. On the other hand, the maternal care of control mothers does not impair learning of rat pups prenatally exposed to methamphetamine. The present study demonstrates that cross-fostering may affect learning in adulthood.

Impact of prenatal and acute methamphetamine exposure on behaviour of adult male rats

Psychostimulants have been shown to alter behaviour in both rats and humans. The aim of the present study was: (1) to assess the effect of prenatal and acute methamphetamine (MA) administration on behaviour in adult male rats and (2) to find out if the prenatal exposure to MA increases sensitivity to acute MA application in adulthood. Behaviour of adult male rats prenatally exposed to MA (5 mg/kg) or no drug was tested in Open field (OF) and Elevated plus maze (EPM). Half of the animals were injected with MA (1 mg/kg) subcutaneously 30 minutes prior to testing. Locomotion, exploration, comforting behaviour and anxiety were evaluated in the OF, while anxiety and exploratory behaviour were assessed in the EPM. Our results showed that prenatal MA did not have an effect on baseline behaviour in either of the tests. By contrast, acute MA increased overall psychomotor activity by increasing locomotion and exploratory behaviour and decreasing comforting behaviour. Moreover, adult rats prenatally exposed to MA were more sensitive to the effects of acute MA on exploration. In addition, acute MA application decreased anxiety in the OF as well as in the EPM. Our present study, thus, demonstrates that acute MA increases overall psychomotor activity and decreases anxiety to novel environment. To further support our hypothesis that prenatal MA exposure increases sensitivity to drugs in adulthood, studies investigating the levels of dopamine in the rat brain after prenatal MA exposure are planned.

Cross-fostering effect on postnatal development of rat pups exposed to methamphetamine during gestation and preweaning periods

There are studies showing that drug abuse during pregnancy may have a long-term effect on progeny of drug-abusing mothers. Our previous work demonstrated that prenatal and/or postnatal methamphetamine injections impair maternal behavior. The purpose of the present study was to assess the effect of prenatal methamphetamine or stress exposure and postnatal breeding on postnatal development of rat pups. Female rats were injected with methamphetamine (5 mg/kg daily) or physiological saline prior, during and after gestation. Absolute controls did not receive any injections. On postnatal day 1, pups were cross-fostered so that each mother received some of her own and some of the pups from the mothers with the other two treatments. Pups were weighted daily for the entire lactation period. Postural motor reaction development was examined daily by righting reflex between postnatal day 1 and 12. On postnatal day 15 homing test examining pups' nest-seeking behavior was performed. On postnatal day 23 rotarod and bar-holding tests were used to investigate sensorimotor coordination of pups. We demonstrated that prenatal methamphetamine exposure impairs performance of sensorimotor tests (righting reflex on surface and rotarod test). Moreover, the effect of methamphetamine as well as the effect of prenatal stress induced by saline injections was affected by postnatal breeding conditions in sensorimotor tests as well as in the test of homing. Our results support the hypothesis that the variation in rat maternal care could serve as a mechanism for a nongenomic behavioral mode of transmission of traits.

Cognitive functions and drug sensitivity in adult male rats prenatally exposed to methamphetamine

The aim of the present study was to investigate the impact of prenatal methamphetamine (MA) exposure and application of the same drug in adulthood on cognitive functions of adult male rats tested in Morris water maze (MWM). Adult male rats prenatally exposed to MA (5 mg/kg), saline or no injection were examined. Half of the animals were injected daily with MA (1 mg/kg) after finishing the testing. Three types of tests were used: (1) "Place navigation test" (Learning), (2) "Probe test" and (3) "Retention memory test" (Memory). Our results showed that prenatal MA exposure did not affect the test of learning and the Probe test. In the test of memory prenatally MA-exposed rats showed smaller search errors and used spatial strategies more than both control groups. Further, MA application in adulthood prolonged trajectories, increased the incidence of random search and decreased the incidence of direct swim in the Place navigation test. In addition, MA administration in adulthood increased the speed of swimming regardless of prenatal exposure. The present study thus demonstrates that 1) Prenatal MA exposure does not affect learning in the MWM, 2) Prenatal MA exposure improves performance in the Retention memory test in the MWM, and 3) MA application in adulthood impairs learning in the Morris water maze.

Prenatal and perinatal factors influencing nociception, addiction and behavior during ontogenetic development

This review, which summarizes our findings concerning the long-term effects of pre-, peri- and postnatal factors affecting development, nociception and sensorimotor functions, focuses on three areas: 1) perinatal factors influencing nociception in adult rats were examined in rats with hippocampal lesions, after the administration of stress influencing and psychostimulant drugs (dexamethasone, indomethacine and methamphetamine); 2) the effect of pre- and early postnatal methamphetamine administration was shown to impair the development of sensorimotor functions tested in rat pups throughout the preweaning period; 3) the effect of extensive dorsal rhizotomy of the brachial plexus during the early postnatal period was studied with respect to neuropathic pain development and sensorimotor functions. The present study indicates that prenatal or neonatal stress, as well as various drugs, may disturb the development of the nociceptive system and cause long-term behavioral changes persisting to adulthood and that some types of neuropathic pain cannot be induced during the first two postnatal weeks at all. A mature nervous system is required for the development of the described pathological behaviors.

Does cross-fostering modify the impairing effect of methamphetamine on postnatal development of rat pups?

Our previous studies demonstrated that methamphetamine (MA) administered during gestation and lactation periods impairs maternal behavior as well as the postnatal development of rat pups. The present study tested the hypothesis that the cross-fostering influences the development of rat pups. Mothers were daily exposed to injection of MA (5 mg/kg) and saline for 9 weeks: three weeks prior to impregnation, throughout the entire gestation period and during lactation. As a control (C) females with no injections were used. On postnatal day (PD 1), pups were cross-fostered so that each mother received some of her own and some of the pups of mother with the other treatments. Pup's development and sensorimotor coordination was examined between PD 1 and PD 23. Following tests were used: tail pull (PD 10), righting reflex on surface (PD 12), righting reflex on mid-air (PD 17) and rotarod (PD 23). Our results showed that the birth weight in prenatally MA-exposed pups was lower than controls or saline-exposed pups regardless of sex. Prenatally MA-exposed pups gained less weight than controls or saline-exposed pups regardless of postnatal treatment and sex. Further, our data demonstrated that prenatal and postnatal MA exposure impairs sensorimotor functions. On the other hand, postnatal care of control mothers at least partially suppressed the negative effect of prenatal MA exposure. Our hypothesis, that the cross-fostering may affect postnatal development of pups, was confirmed. Our results support the hypothesis that variation in rat maternal care could serve as a mechanism for a non-genomic behavioral mode of transmission of traits.

Impact of methamphetamine administered prenatally and in adulthood on cognitive functions of male rats tested in Morris water maze

Studies showed that stimulant drugs that affect the monoaminergic system alter both behavioral and cognitive processes. The aim of the present study was to investigate the impact of prenatal and acute methamphetamine (MA) exposure on cognitive functions of adult male rats tested in Morris water maze (MWM). We tested adult male rats prenatally exposed to MA (5 mg/kg), saline or no injection. Half of the animals were injected daily with MA (1 mg/kg) after finishing the testing. All injections were administered subcutaneously. Three types of tests were used: (1) "Place navigation test" (Learning), (2) "Probe test" (Probe) and (3) "Retention memory test" (Memory). Our results showed that prenatal MA exposure did not affect the test of learning and the Probe test. In the test of memory prenatally MA-exposed rats had lower latencies than animals prenatally exposed to saline. Further, acute MA administration increased the speed of swimming in all rats regardless of prenatal drug exposure and the type of test and, however, the increase in the speed was significantly greater in rats prenatally exposed to MA than in rats without any prenatal exposure. In addition, acute MA application significantly prolonged trajectories in the Place navigation test. The present study thus demonstrates that: (1) Prenatal MA exposure does not affect learning in the MWM. (2) Prenatal MA exposure increases the sensitivity to acute drug injection. (3) Acute MA application impairs learning in the MWM.