The effect of adolescent inhalant abuse on energy balance and growth

Abuse-like toluene exposure during early adolescence alters subsequent ethanol and cocaine behavioral effects and brain monoamines in male mice

Currently, there is a gap in understanding the neurobiological impact early adolescent toluene exposure has on subsequent actions of other drugs. Adolescent (PND 28-32) male Swiss-Webster mice (N = 210) were exposed to 0, 2000, or 4000 ppm of toluene vapor for 30 min/day for 5 days. Immediately following the last toluene exposure (PND 32; n = 15) or after a short delay (PND 35; n = 15), a subset of subjects' brains was collected for monoamine analysis. Remaining mice were assigned to one of two abstinence periods: a short 4-day (PND 36) or long 12-day (PND 44) delay after toluene exposure. Mice were then subjected to a cumulative dose response assessment of either cocaine (0, 2.5, 5, 10, 20 mg/kg; n = 60), ethanol (0, 0.5, 1, 2, 4 g/kg; n = 60), or saline (5 control injections; n = 60). Toluene concentration-dependently increased locomotor activity during exposure. When later challenged, mice exposed previously to toluene were significantly less active after cocaine (10 and 20 mg/kg) compared to air-exposed controls. Animals were also less active at the highest dose of alcohol (4 g/kg) following prior exposure to 4000 ppm when compared to air-exposed controls. Analysis of monoamines and their metabolites using High Pressure Liquid Chromatography (HPLC) within the medial prefrontal cortex (mPFC), nucleus accumbens (NAc), dorsal striatum (dSTR), and ventral tegmental area (VTA) revealed subtle effects on monoamine or metabolite levels following cumulative dosing that varied by drug (cocaine and ethanol) and abstinence duration. Our results suggest that early adolescent toluene exposure produces behavioral desensitization to subsequent cocaine-induced locomotor activity with subtle enhancement of ethanol's depressive effects and less clear impacts on levels of monoamines.

Early-onset alcohol, tobacco, and illicit drug use with age at onset of hypertension: a survival analysis

PURPOSE

To examine the associations of age when first substance use and early-onset substance use before age 18 with age at onset (AAO) of hypertension.

METHODS

This study included 19,270 individuals with AAO of hypertension from the 2015-2019 National Survey on Drug Use and Health. Age when first use of 10 substance use variables included alcohol, daily cigarettes, cigars, smokeless tobacco, marijuana, cocaine, hallucinogens, lysergic acid diethylamide (LSD), inhalants, and methamphetamine use. The outcome was AAO of hypertension and variable cluster analysis was used to classify the exposures and outcome. Substance use status was classified into three categories: early-onset substance use (first used substance before age 18), late-onset substance use (first used substance after age 18), and never used.

RESULTS

The mean AAO of hypertension was 42.7 years. Age when first use of 10 substance use variables had significant correlations with AAO of hypertension (all p values < 0.001). Individuals with early-onset alcohol, cigars, smokeless tobacco, marijuana, hallucinogens, inhalants, cocaine, LSD, and methamphetamine use revealed significantly earlier onset of hypertension than those never used. Compared with never used substances, the Cox regression model showed that early-onset alcohol, smokeless tobacco, marijuana, inhalants, and methamphetamine use had an increased risk of AAO of hypertension [hazard ratio (HR) (95%CI) = 1.22 (1.13, 1.31), 1.36 (1.24, 1.49), 1.85 (1.75, 1.95), 1.41 (1.30, 1.52), and 1.27 (1.07,1.50), respectively].

CONCLUSION

These findings suggest that intervention strategies or programs focusing on preventing early-onset substance use before age 18 may delay the onset of adult hypertension.

Repeated toluene and cyclohexane inhalation produces differential effects on HPA and HPT axes in adolescent male rats

Misused volatile solvents typically contain toluene (TOL) as the main psychoactive ingredient. Cyclohexane (CHX) can also be present and is considered a safer alternative. Solvent misuse often occurs at early stages of life, leading to permanent neurobehavioral impairment and growth retardation. However, a comprehensive examination of the effects of TOL and CHX on stress regulation and energy balance is lacking. Here, we compared the effect of a binge-pattern exposure to TOL or CHX (4,000 or 8,000 ppm) on body weight, food intake, the hypothalamus-pituitary-adrenal (HPA) and hypothalamus-pituitary-thyroid (HPT) axes in male adolescent Wistar rats. At 8,000 ppm, TOL decreased body weight gain without affecting food intake. In addition, TOL and CHX altered the HPA and HPT axes' function in a solvent- and concentration-dependent manner. The highest TOL concentration produced HPA axis hyperactivation in animals not subjected to stress, which was evidenced by increased corticotropin-releasing-factor (CRF) release from the median eminence (ME), elevated adrenocorticotropin hormone (ACTH) and corticosterone serum levels, and decreased CRF mRNA levels in the hypothalamic paraventricular nucleus (PVN). TOL (8,000 ppm) also increased triiodothyronine (T3) serum levels, decreased pro-thyrotropin-releasing-hormone (pro-TRH) mRNA transcription in the PVN, pro-TRH content in the ME, and serum thyroid stimulating hormone (TSH) levels. CHX did not affect the HPA axis. We propose that the increased HPT axis activity induced by TOL can be related to the impaired body weight gain associated with inhalant misuse. These findings may contribute to a better understanding of the effects of the misused solvents TOL and CHX.

Body dissatisfaction, drug use, and associated factors among adolescents in three Brazilian cities

OBJECTIVE

analyze the association between drug use and body dissatisfaction among adolescents in three Brazilian cities.

METHOD

cross-sectional study, using a nested randomized controlled trial to evaluate the drug use prevention program #TamoJunto2.0 of the Ministry of Health in Brazilian schools. The sample consisted of 5,213 students from 73 schools in three Brazilian cities. The outcome body satisfaction was analyzed using the Stunkard scale and the explanatory variables were drug use and sociodemographic data.

RESULTS

the adolescents were between 12 and 14 years old; about 69.9% of them reported body dissatisfaction, and 35.67% used alcohol in the previous year. Dissatisfaction due to overweight was higher among girls (41.5%) and dissatisfaction due to underweight was higher among boys (33.1%). Adolescents who used marijuana were 39% (OR=1.39) more likely to feel dissatisfied due to underweight and being a girl increased the chances of feeling dissatisfied due to overweight by 24% (OR=1.24).

CONCLUSION

the levels of body dissatisfaction deserve attention in hebiatric nursing care and reinforce the importance of educational strategies addressing body image and drug use, relating them to the various subjective attributes that can affect the health of adolescents, whether in the community or at school.

(1) High prevalence of body dissatisfaction related to overweight. (2) Girls presented 24% more chances of feeling body dissatisfaction due to overweight. (3) Marijuana use in adolescence can increase by 39% body dissatisfaction due to underweight. (4) Last year, about 35.7% of adolescents had already consumed alcohol. (5) Health promotion and stimulation of positive perceptions of self-image.

Insatisfacción con la imagen corporal, uso de drogas y factores asociados entre adolescentes en tres ciudades brasileñas

Resumen Objetivo: analizar la asociación entre uso de drogas y la insatisfacción con la imagen corporal de adolescentes en tres ciudades brasileñas. Método: estudio transversal, anidado en un ensayo controlado aleatorio para evaluar el programa de prevención del uso de drogas en escuelas brasileñas #TamoJunto2.0 del Ministerio de la Salud. La muestra fue de 5.213 alumnos de 73 escuelas de tres ciudades brasileñas. El desenlace satisfacción corporal se analizó mediante la escala de Siluetas de Stunkard y las variables explicativas fueron el consumo de drogas y los datos sociodemográficos. Resultados: los adolescentes tenían entre 12 y 14 años y alrededor del 69,9% relató insatisfacción corporal, y en el último año el 35,67% consumió alcohol. La insatisfacción por sobrepeso fue mayor en las niñas (41,5%) y por bajo peso en los niños (33,1%). Los adolescentes que consumían marihuana tenían un 39% (OR=1,39) más de probabilidades de estar insatisfechos con el bajo peso y ser niña aumentó en un 24% (OR=1,24) las chances de insatisfacción por sobrepeso. Conclusión: los niveles de insatisfacción corporal merecen atención en el cuidado de enfermería hebiátrica y refuerzan la necesidad de estrategias educativas abordando la imagen corporal y el uso de drogas, relacionándola a los varios atributos subjetivos que pueden afectar la salud de los adolescentes, ya sea en la comunidad o en la escuela.

Insatisfação com a imagem corporal, uso de drogas e fatores associados entre adolescentes em três cidades brasileiras

Resumo Objetivo: analisar a associação entre uso de drogas e a insatisfação com a imagem corporal de adolescentes em três cidades brasileiras. Método: estudo transversal, aninhado em um ensaio controlado randomizado para avaliar o programa de prevenção ao uso de drogas em escolas brasileiras #TamoJunto2.0 do Ministério da Saúde. A amostra foi de 5.213 alunos de 73 escolas de três cidades brasileiras. O desfecho satisfação corporal foi analisado por meio da escala de Silhuetas de Stunkard e as variáveis explicativas foram o uso de drogas e dados sociodemográficos. Resultados: os adolescentes tinham entre 12 e 14 anos e cerca de 69,9% relataram insatisfação corporal, e no último ano 35,67% utilizaram álcool. A insatisfação por sobrepeso foi maior nas meninas (41,5%) e por baixo peso nos meninos (33,1%). Os adolescentes que usavam maconha apresentaram 39% (OR=1,39) mais chance de insatisfação por baixo peso e ser menina aumentou em 24% (OR=1,24) as chances de insatisfação por sobrepeso. Conclusão: os níveis de insatisfação corporal merecem atenção no cuidado de enfermagem hebiátrica e reforçam a necessidade de estratégias educativas abordando a imagem corporal e uso de drogas, a relacionando aos vários atributos subjetivos que podem afetar a saúde dos adolescentes, seja na comunidade ou escola.

Exploring the link between adolescent inhalant misuse and suicidal behaviour: a behavioural toxicology perspective

Adolescent inhalant misuse has a known association with suicidal thoughts and behaviour. This association persists even after inhalant misuse has ceased. Previous studies have hypothesised that this association may derive from socioeconomic disadvantage or vulnerability, and potentially mediated by impulsivity. This association may also be due to the central nervous system depressant effects of inhalants. This review takes a behavioural toxicology perspective, focussed particularly on the serotonergic system and the Hypothalamic-Pituitary-Adrenal (HPA) axis, as potential links between adolescent inhalant misuse and suicidal behaviour. The challenges of bridging the pre-clinical and clinical literature in this area are discussed, along with promising avenues for future research; ultimately aimed at reducing suicide risk in a vulnerable adolescent population group.

The last two decades on preclinical and clinical research on inhalant effects

This paper reviews the scientific evidence generated in the last two decades on the effects and mechanisms of action of most commonly misused inhalants. In the first section, we define what inhalants are, how they are used, and their prevalence worldwide. The second section presents specific characteristics that define the main groups of inhalants: (a) organic solvents; (b) aerosols, gases, and volatile anesthetics; and (c) alkyl nitrites. We include a table with the molecular formula, structure, synonyms, uses, physicochemical properties and exposure limits of representative compounds within each group. The third and fourth sections review the direct acute and chronic effects of common inhalants on health and behavior with a summary of mechanisms of action, respectively. In the fifth section, we address inhalant intoxication signs and available treatment. The sixth section examines the health effects, intoxication, and treatment of nitrites. The seventh section reviews current intervention strategies. Finally, we propose a research agenda to promote the study of (a) solvents other than toluene; (b) inhalant mixtures; (c) effects in combination with other drugs of abuse; (d) age and (e) sex differences in inhalant effects; (f) the long-lasting behavioral effects of animals exposed in utero to inhalants; (g) abstinence signs and neurochemical changes after interrupting inhalant exposure; (h) brain networks involved in inhalant effects; and finally (i) strategies to promote recovery of inhalant users.

Adolescent chronic intermittent toluene inhalation dynamically regulates the transcriptome and neuronal methylome within the rat medial prefrontal cortex

Inhalants containing the volatile solvent toluene are misused to induce euphoria or intoxication. Inhalant abuse is most common during adolescence and can result in cognitive impairments during an important maturational period. Despite evidence suggesting that epigenetic modifications may underpin the cognitive effects of inhalants, no studies to date have thoroughly investigated toluene-induced regulation of the transcriptome or discrete epigenetic modifications within the brain. To address this, we investigated effects of adolescent chronic intermittent toluene (CIT) inhalation on gene expression and DNA methylation profiles within the rat medial prefrontal cortex (mPFC), which undergoes maturation throughout adolescence and has been implicated in toluene-induced cognitive deficits. Employing both RNA-seq and genome-wide Methyl CpG Binding Domain (MBD) Ultra-seq analysis, we demonstrate that adolescent CIT inhalation (10 000 ppm for 1 h/day, 3 days/week for 4 weeks) induces both transient and persistent changes to the transcriptome and DNA methylome within the rat mPFC for at least 2 weeks following toluene exposure. We demonstrate for the first time that adolescent CIT exposure results in dynamic regulation of the mPFC transcriptome likely relating to acute inflammatory responses and persistent deficits in synaptic plasticity. These adaptations may contribute to the cognitive deficits associated with chronic toluene exposure and provide novel molecular targets for preventing long-term neurophysiological abnormalities following chronic toluene inhalation.

Harms associated with inhalant misuse in adolescent females - a review of the pre-clinical and clinical evidence

BACKGROUND

Inhalant misuse, or the misuse of products containing toluene is common in adolescents, and is associated with diverse physiological and psychological harms. Females comprise over half those who misuse inhalants in adolescence, however, the majority of the evidence has been derived from male-only or mixed-sex studies without exploration of sex differences. Female adolescence is a critical maturational period with potential for growth, reproductive, cognitive and psychological harms that may lead to long-term health consequences. We therefore summarise evidence of female-specific harms arising from inhalant misuse.

METHODS

We synthesised pre-clinical and clinical studies of inhalant misuse which were conducted in females, or where sex-differences were reported, into a narrative literature review.

RESULTS

Females experience growth impairments and metabolic dysfunction arising from inhalant misuse, but data on sex-differences are inconclusive. Inhalant misuse in early adolescence may impact menarche and subsequent reproductive capacity, but studies have predominantly focused on the effects of inhalants on offspring rather than on the exposed female. There is limited evidence of sex-differences in relation to cognitive outcomes following exposure to inhalants in pre-clinical models. Females are at an increased risk of psychological harms associated with inhalant misuse, particularly depression and suicidal behaviour.

CONCLUSIONS

The type and magnitude of harms associated with inhalant misuse are sex-specific, but data are limited. We recommend that both pre-clinical and clinical studies of inhalant misuse include both males and females, and should specifically test for and report sex-differences. This can be used to build an evidence base for screening and interventions tailored to females.

Minocycline prevents neuronal hyperexcitability and neuroinflammation in medial prefrontal cortex, as well as memory impairment caused by repeated toluene inhalation in adolescent rats

Toluene can be intentionally misused by adolescents to experience psychoactive effects. Toluene has a complex mechanism of action and broad behavioral effects, among which memory impairment is reported consistently. We have previously reported that repeated toluene inhalation (8000 ppm) increases layer 5 prelimbic pyramidal cells' excitability in the medial prefrontal cortex (mPFC) of adolescent rats. Toluene also produces reactive oxygen species (ROS), which activate glial cells. Here, we tested the hypothesis that the anti-inflammatory agent minocycline would decrease toluene's effects because it inhibits NF-κB (nuclear factor enhancer of the kappa light chains of activated B cells) and reduces pro-inflammatory cytokine and ROS production. Our results show that minocycline (50 mg/kg, ip, for 10 days) prevents the hyperexcitability of mPFC neurons observed after repeated 8000 ppm toluene exposure (30 min/day, 2×/day for 10 days). Minocycline prevents toluene-induced hyperexcitability by a mechanism that averts the loss of the slow calcium-dependent potassium current, and normalizes mPFC neurons' firing frequency. These effects are accompanied by significant decreased expression of astrocytes and activated microglia in the mPFC, reduced NLRP3 inflammasome activation and mRNA expression levels of the pro-inflammatory cytokine interleukin 1β (IL-1β), as well as increased mRNA expression of the anti-inflammatory cytokine transforming growth factor β (TGF-β). Minocycline also prevents toluene-induced memory impairment in adolescent rats in the passive avoidance task and the temporal order memory test in which the mPFC plays a central role. These results show that neuroinflammation produces several effects of repeated toluene administration at high concentrations, and minocycline can significantly prevent them.