Long-term use of methamphetamine disrupts the menstrual cycles and hypothalamic-pituitary-ovarian axis

The estrous cycle has no effect on incubation of methamphetamine craving and associated Fos expression in dorsomedial striatum and anterior intralaminar nucleus of thalamus

Relapse is a major challenge in treating drug addiction, and drug seeking progressively increases after abstinence, a phenomenon termed "incubation of drug craving". Previous studies demonstrated both sex differences and an effect of estrous cycle in female rats in incubation of cocaine craving. In contrast, while incubation of methamphetamine craving is similar across sexes, whether estrous cycle plays a role in this incubation has yet to be fully addressed. Moreover, whether neural mechanisms underlying incubation of methamphetamine craving differ across estrous cycles is largely unknown. To address these gaps, we first compared methamphetamine self-administration, and methamphetamine seeking on both abstinence days 1 and 28 between male rats and female rats across the estrous cycle. Next, we examined neuronal activation associated with incubated methamphetamine seeking in dorsomedial striatum (DMS) and lateral portion of the anterior intralaminar nucleus of thalamus (AIT-L), two brain areas previously implicated in incubation of methamphetamine craving. We found no effect of sex or estrous cycle on methamphetamine self-administration and methamphetamine seeking on abstinence days 1 and 28. We also found no effect of sex or estrous cycle on the number of Fos-expressing cells in DMS or AIT-L following methamphetamine seeking test. Taken together, our results showed that methamphetamine self-administration and incubation of methamphetamine craving was not dependent on sex or estrous cycles under our experimental condition, and the role of DMS and AIT-L in incubation of methamphetamine craving may be similar across sexes and across estrous cycles in female rats.

Modeling methamphetamine use disorder and relapse in animals: short- and long-term epigenetic, transcriptional., and biochemical consequences in the rat brain

Methamphetamine use disorder (MUD) is a neuropsychiatric disorder characterized by binge drug taking episodes, intervals of abstinence, and relapses to drug use even during treatment. MUD has been modeled in rodents and investigators are attempting to identify its molecular bases. Preclinical experiments have shown that different schedules of methamphetamine self-administration can cause diverse transcriptional changes in the dorsal striatum of Sprague-Dawley rats. In the present review, we present data on differentially expressed genes (DEGs) identified in the rat striatum following methamphetamine intake. These include genes involved in transcription regulation, potassium channel function, and neuroinflammation. We then use the striatal data to discuss the potential significance of the molecular changes induced by methamphetamine by reviewing concordant or discordant data from the literature. This review identified potential molecular targets for pharmacological interventions. Nevertheless, there is a need for more research on methamphetamine-induced transcriptional consequences in various brain regions. These data should provide a more detailed neuroanatomical map of methamphetamine-induced changes and should better inform therapeutic interventions against MUD.

Linalool attenuates hypothalamus proteome disturbance facilitated by methamphetamine induced neurotoxicity in rats

BACKGROUND

One of the most powerful stimulants of the central nervous system is methamphetamine (METH). Linalool has a neuroprotective effect against ischemia injury by reducing oxidative stress and apoptosis. The present study investigated whether linalool can reverse the hypothalamus neurotoxicity and proteome disturbance in METH-treated rats.

BRIEF METHOD

A total of 36 male albino rats were split into two equal groups (normal and METH-treated). Three equal subgroups of normal rats were created; Control, Linalool (25 mg/kg), and Linalool (50 mg/kg); Normal rats were given daily oral doses of 1 ml of distilled water, 25 mg/kg linalool, and 50 mg/kg of linalool, respectively. METH groups were divided into 3 equal subgroups; METH-treated rats, Linalool (25 mg/kg)+METH-treated, and Linalool (50 mg/kg)+METH-treated subgroups; METH-treated rats received daily and oral doses of 1 ml distilled water, 25 mg/kg linalool, and 50 mg/kg of linalool, respectively.

RESULTS

According to the data obtained, METH caused a decrease of the sucrose preference test, travel distance test, and center square entries test, superoxide dismutase, glutathione peroxidase, catalase, NADPH oxidase, interleukin-10 but a rise in the center square duration test, tail suspension test, and forced swimming test, malondialdehyde, conjugated dienes, oxidative index, serotonin, dopamine, norepinephrine, γ-aminobutyric acid, tumour necrosis factor-α, interleukin-1β, interleukin-6 levels. When compared to the control group, rats treated with METH had lower sodium/potassium ATPase activity and missing of prothrombin, fibrinogen, and ceruloplasmin protein bands in the hypothalamus. In METH-treated rats, daily and oral co-administration with linalool brought all these parameters back to values that were close to control.

SIGNIFICANCE

According to obtained data, linalool could protect the hypothalamus against METH-induced neurotoxicity and proteome disturbance probably by modifying oxidative stress, neurotransmitters, inflammation, sodium/potassium-ATPase activity, proteome disturbance, and tissue histology in METH-treated rats where higher dose of linalool was more efficient than lower dose.

Methamphetamine-induced vaginal lubrication in rats

BACKGROUND

Based on previous studies of vaginal lubrication as well as our own previously reported interview study of women who self-reported methamphetamine (meth)-induced vaginal lubrication, in the current study we sought to determine the potential dose-response relationship leading to meth-induced vaginal lubrication. We also developed an animal model to study the reported effects and examine potential mechanisms mediating this phenomenon.

AIM

We sought to characterize the effects of meth on vaginal lubrication in an animal model with the aim of providing a potential framework for new mechanisms that incorporate novel therapeutic agents for the treatment of vaginal dryness.

METHODS

Vaginal lubrication was measured via insertion of a preweighed, cotton-tipped swab into the vaginal canal of anesthetized rats following treatment with various doses of intravenous (IV) meth, up to 0.96 mg/kg, and after additional pharmacological manipulations, including administration of a nitric oxide synthase inhibitor and an estrogen receptor antagonist. Plasma signaling molecules, including estradiol, progesterone, testosterone, nitric oxide, and vasoactive intestinal polypeptide, were measured immediately before and at 9 time points after IV meth administration. Blood was collected via a previously implanted chronic indwelling jugular catheter and analyzed by use of commercially available kits per the manufacturer's instructions.

OUTCOMES

Outcomes for this study include the measurement of vaginal lubrication in anesthetized rats following various pharmacological manipulations and plasma levels of various signaling molecules.

RESULTS

Meth dose-dependently increased vaginal lubrication in anesthetized female rats. Meth significantly increased plasma levels compared to baseline of estradiol (2 and 15 minutes after meth infusion) as well as progesterone, testosterone, and nitric oxide (10 minutes after meth infusion). Also, vasoactive intestinal polypeptide decreased significantly compared to baseline for 45 minutes following meth infusion. Our data further suggest that nitric oxide, but not estradiol, is critical in the production of vaginal secretions in response to meth.

CLINICAL IMPLICATIONS

This study has far-reaching implications for women who are suffering from vaginal dryness and for whom estrogen therapy is unsuccessful, as the investigation has demonstrated that meth presents a novel mechanism for producing vaginal lubrication that can be targeted pharmacologically.

STRENGTHS AND LIMITATIONS

This study is, to our knowledge, the first performed to measure the physiological sexual effects of meth in an animal model. Animals were anesthetized when they were administered meth. In an ideal situation, animals would be self-administering the drug to recapitulate better the contingent nature of drug taking; however, this method was not feasible for the study reported here.

CONCLUSION

Methamphetamine increases vaginal lubrication in female rats through a nitric oxide-dependent mechanism.

A gender-based secondary analysis of the ADAPT-2 combination naltrexone and bupropion treatment for methamphetamine use disorder trial

BACKGROUND AND AIMS

Socio-cultural (gender) and biological (sex)-based differences contribute to psychostimulant susceptibility, potentially affecting treatment responsiveness among women with methamphetamine use disorder (MUD). The aims were to measure (i) how women with MUD independently and compared with men respond to treatment versus placebo and (ii) among women, how the hormonal method of contraception (HMC) affects treatment responsiveness.

DESIGN

This was a secondary analysis of ADAPT-2, a randomized, double-blind, placebo-controlled, multicenter, two-stage sequential parallel comparison design trial.

SETTING

United States.

PARTICIPANTS

This study comprised 126 women (403 total participants); average age = 40.1 years (standard deviation = 9.6) with moderate to severe MUD.

INTERVENTIONS

Interventions were combination intramuscular naltrexone (380 mg/3 weeks) and oral bupropion (450 mg daily) versus placebo.

MEASUREMENTS

Treatment response was measured using a minimum of three of four negative methamphetamine urine drug tests during the last 2 weeks of each stage; treatment effect was the difference between weighted treatment responses of each stage.

FINDINGS

At baseline, women used methamphetamine intravenously fewer days than men [15.4 versus 23.1% days, P = 0.050, difference = -7.7, 95% confidence interval (CI) = -15.0 to -0.3] and more women than men had anxiety (59.5 versus 47.6%, P = 0.027, difference = 11.9%, 95% CI = 1.5 to 22.3%). Of 113 (89.7%) women capable of pregnancy, 31 (27.4%) used HMC. In Stage 1 29% and Stage 2 5.6% of women on treatment had a response compared with 3.2% and 0% on placebo, respectively. A treatment effect was found independently for females and males (P < 0.001); with no between-gender treatment effect (0.144 females versus 0.100 males; P = 0.363, difference = 0.044, 95% CI = -0.050 to 0.137). Treatment effect did not differ by HMC use (0.156 HMC versus 0.128 none; P = 0.769, difference = 0.028, 95% CI -0.157 to 0.212).

CONCLUSIONS

Women with methamphetamine use disorder receiving combined intramuscular naltrexone and oral bupropion treatment achieve greater treatment response than placebo. Treatment effect does not differ by HMC.

The effect of adolescent social isolation on vulnerability for methamphetamine addiction behaviours in female rats

RATIONALE

Stress exposure during adolescence contributes to developing a methamphetamine (METH) use disorder. However, most of the studies investigating addiction-related behaviours include only male rodents, despite METH addiction rates being higher in females. Furthermore, animal studies investigating the effects of stress on methamphetamine addiction have used only basic self-administration models which may not be sensitive to the effects of stress.

OBJECTIVES

This project explored whether adolescent isolation stress exposure increases the incidence of four key addiction-related behaviours in female rats.

METHODS

Thirty-two female rat pups were caged in groups of four or individually during adolescence from postnatal (PND) day 22, with the latter being re-socialised in groups of four on PND 43. In adulthood, rats were tested for addiction-like behaviours in a METH self-administration paradigm modelling motivation to take METH, persistence in drug-seeking behaviour when METH was not available, resistance to extinction, and propensity to reinstate after a period of withdrawal.

RESULTS

Adolescent social isolation resulted in lower METH intake during acquisition; however, the paradigm modelling drug-seeking when the drug was unavailable engendered intermittent METH bingeing in all rats, abolishing the group differences in intake during this phase. Adolescent social isolation also accelerated extinction of non-reinforced lever pressing, and increased stress-primed reinstatement, compared to the group-housed rats.

CONCLUSIONS

Adolescent social isolation stress alters various methamphetamine addiction-like behaviours in female rats.

The Adverse Effects of Prenatal METH Exposure on the Offspring: A Review

Abuse of methamphetamine (METH), an illicit psychostimulant, is a growing public health issue. METH abuse during pregnancy is on the rise due to its stimulant, anorectic, and hallucinogenic properties. METH can lead to multiple organ toxicity in adults, including neurotoxicity, cardiovascular toxicity, and hepatotoxicity. It can also cross the placental barrier and have long-lasting effects on the fetus. This review summarizes neurotoxicity, cardiovascular toxicity, hepatotoxicity, toxicity in other organs, and biomonitoring of prenatal METH exposure, as well as the possible emergence of sensitization associated with METH. We proposed the importance of gut microbiota in studying prenatal METH exposure. There is rising evidence of the adverse effects of METH exposure during pregnancy, which are of significant concern.

Voluntary Pregnancy Screening at Syringe Exchanges: A Feasibility Study

The purpose of this study was to explore the feasibility of offering voluntary pregnancy screening at syringe exchange programs using the National Implementation Research Network Hexagon Discussion and Analysis Tool. We conducted a survey among female syringe exchange clients that assessed perceived needs, values, and behavioral intentions for parenting and entering treatment if they received a positive pregnancy screen and surveys among staff and core volunteers to assess organizational fit, capacity, and needed supports. Participants and staff reported that pregnancy screening was needed at syringe exchange and that capacity needs to be expanded to provide services. Pregnancy screening at syringe exchanges holds the potential to lead to early detection of pregnancy. Early detection of pregnancy among women who inject drugs may result in improved prenatal care, including substance use treatment and treatment of infectious diseases, for women who would otherwise be unlikely to receive prenatal care.

Methamphetamine-induced changes in myocardial gene transcription are sex-dependent

BACKGROUND

Prior work demonstrated that female rats (but not their male littermates) exposed to methamphetamine become hypersensitive to myocardial ischemic injury. Importantly, this sex-dependent effect persists following 30 days of subsequent abstinence from the drug, suggesting that it may be mediated by long term changes in gene expression that are not rapidly reversed following discontinuation of methamphetamine use. The goal of the present study was to determine whether methamphetamine induces sex-dependent changes in myocardial gene expression and whether these changes persist following subsequent abstinence from methamphetamine.

RESULTS

Methamphetamine induced changes in the myocardial transcriptome were significantly greater in female hearts than male hearts both in terms of the number of genes affected and the magnitude of the changes. The largest changes in female hearts involved genes that regulate the circadian clock (Dbp, Per3, Per2, BMal1, and Npas2) which are known to impact myocardial ischemic injury. These genes were unaffected by methamphetamine in male hearts. All changes in gene expression identified at day 11 returned to baseline by day 30.

CONCLUSIONS

These data demonstrate that female rats are more sensitive than males to methamphetamine-induced changes in the myocardial transcriptome and that methamphetamine does not induce changes in myocardial transcription that persist long term after exposure to the drug has been discontinued.

Does Prenatal Exposure to CNS Stimulants Increase the Risk of Cardiovascular Disease in Adult Offspring?

Prenatal exposure to an adverse uterine environment can have long lasting effects on adult offspring through DNA methylation, histone acetylation, and other epigenetic effects that alter gene expression and physiology. It is well-known that consumption of CNS stimulants such as caffeine, nicotine, amphetamines, and cocaine during pregnancy can adversely impact the offspring. However, most work in this area has focused on neurological and behavioral outcomes and has been limited to assessments in young offspring. The impact of prenatal exposure to these agents on the adult cardiovascular system has received relatively little attention. Evidence from both animal and human studies indicate that exposure to CNS stimulants during the gestational period can negatively impact the adult heart and vasculature, potentially leading to cardiovascular diseases later in life. This review discusses our current understanding of the impact of prenatal exposure to cocaine, methamphetamine, nicotine, and caffeine on the adult cardiovascular system.

Supraphysiologic-dose anabolic-androgenic steroid use: A risk factor for dementia?

Supraphysiologic-dose anabolic-androgenic steroid (AAS) use is associated with physiologic, cognitive, and brain abnormalities similar to those found in people at risk for developing Alzheimer's Disease and its related dementias (AD/ADRD), which are associated with high brain β-amyloid (Aβ) and hyperphosphorylated tau (tau-P) protein levels. Supraphysiologic-dose AAS induces androgen abnormalities and excess oxidative stress, which have been linked to increased and decreased expression or activity of proteins that synthesize and eliminate, respectively, Aβ and tau-P. Aβ and tau-P accumulation may begin soon after initiating supraphysiologic-dose AAS use, which typically occurs in the early 20s, and their accumulation may be accelerated by other psychoactive substance use, which is common among non-medical AAS users. Accordingly, the widespread use of supraphysiologic-dose AAS may increase the numbers of people who develop dementia. Early diagnosis and correction of sex-steroid level abnormalities and excess oxidative stress could attenuate risk for developing AD/ADRD in supraphysiologic-dose AAS users, in people with other substance use disorders, and in people with low sex-steroid levels or excess oxidative stress associated with aging.

Repeated exposure to methamphetamine induces sex-dependent hypersensitivity to ischemic injury in the adult rat heart

Background

We previously reported that adult female, but not male rats that were prenatally exposed to methamphetamine exhibit myocardial hypersensitivity to ischemic injury. However, it is unknown whether hypersensitivity to ischemic injury develops when rats are exposed to methamphetamine during adulthood. The goal of this study was to determine whether methamphetamine exposure during adulthood sensitizes the heart to ischemic injury.

Methods

Adult male and female rats received daily injections of methamphetamine (5 mg/kg) or saline for 10 days. Their hearts were isolated on day 11 and subjected to a 20 min ischemic insult on a Langendorff isolated heart apparatus. Cardiac contractile function was measured by an intraventricular balloon, and infarct size was measured by triphenyltetrazolium chloride staining.

Results

Hearts from methamphetamine-treated females exhibited significantly larger infarcts and suppressed postischemic recovery of contractile function compared to hearts from saline-treated females. In contrast, methamphetamine had no effect on infarct size or contractile recovery in male hearts. Subsequent experiments demonstrated that hypersensitivity to ischemic injury persisted in female hearts following a 1 month period of abstinence from methamphetamine. Myocardial protein kinase C-ε expression, Akt phosphorylation, and ERK phosphorylation were unaffected by adult exposure to methamphetamine.

Conclusions

Exposure of adult rats to methamphetamine sex-dependently increases the extent of myocardial injury following an ischemic insult. These data suggest that women who have a heart attack might be at risk of more extensive myocardial injury if they have a recent history of methamphetamine abuse.

Long-term effects of methamphetamine exposure in adolescent mice on the future ovarian reserve in adulthood

Currently, there is an increasing prevalence of adolescent exposure to methamphetamine (MA). However, there is a paucity of information concerning the long-term impact of early exposure to MA upon female fertility and ovarian reserve. The aim of this study was to investigate the effect of long-term MA exposure in adolescents on their ovarian reserve in adulthood. Adolescent mice received intraperitoneal injections of MA (5mg/kg, three times per week) or saline from the 21st postnatal day for an 8 week period. Morphological, histological, biochemical, hormonal and ethological parameters were evaluated. An impaired ovarian reserve and vitality was found in the group treated with MA, manifesting in morphological-apparent mitochondrial damage, an activated apoptosis pathway in the ovarian tissue, a downward expression of ovarian anti-Mullerian hormone (AMH), a decreased number of primordial and growing follicles, an increased number of atretic follicles, and a depressed secretion of AMH, estradiol and progesterone from granulosa cells. However, no significant difference was noticed regarding the estrous cycle, the mating ability and the fertility outcome in the reproductive age of the mice after a period of non-medication. The present results confirmed that a long term exposure to methamphetamine in adolescent mice does have an adverse impact on their ovarian reserve, which indicates that such an early abuse of MA might influence the fertility lifespan of the female mouse.