Effects of perinatal methylphenidate (MPH) treatment in male and female Sprague–Dawley offspring

Potential disturbance of methylphenidate of gonadal hormones or pubescent development in patients with attention-deficit/hyperactivity disorder: A twelve-month follow-up study

Several animal or case reports have demonstrated that methylphenidate (MPH) disrupts endogenous gonadal hormones and interferes with the pubescent development of children with attention-deficit/hyperactivity disorder (ADHD). Therefore, this prospective study examined the changes in gonadal hormones and pubescent development in children with ADHD undergoing 12-month MPH treatment. We recruited 146 patients with ADHD (mean age: 8.9 years, 76.7% males) and 70 healthy controls (mean age: 9.2 years, 65.7% males). Blood samples were obtained to measure the serum levels of sex hormone-binding globulin (SHBG), follicle stimulating hormone (FSH), luteinizing hormone (LH), estradiol, progesterone, testosterone, free testosterone, and prolactin in each child. The sex maturation of ADHD patients was evaluated using the Tanner Stage. Patients with ADHD (107 received MPH treatment and 39 were under natural observation) were followed up for 12 months, and we re-examined hormone levels and Tanner Stage at the endpoint. During a 12-month follow-up for all ADHD patients, the serum levels of SHBG and progesterone significantly decreased, while LH, FSH, and free-testosterone levels significantly increased. However, the duration, drug formulations, and doses of the MPH treatment did not significantly influence gonadal hormone trends or changes of Tanner Stage. This study provides evidence about gonadal hormone trends and pubescent development in children with ADHD who receive long-term MPH treatment in natural settings. We suggest that MPH treatment at usual doses does not significantly alter gonadal function trends in ADHD patients over the course of one year.

Testicular Function After Long-Term Methylphenidate Treatment in Boys with Attention-Deficit/Hyperactivity Disorder

Objective: Treating attention-deficit/hyperactivity disorder (ADHD) with methylphenidate (MPH) has become increasingly common, while both animal studies and case reports have previously suggested that MPH may exert adverse effects on the reproductive system or gonadal hormones. This study aims to investigate whether long-term MPH treatment of boys with ADHD can induce testicular dysfunction (TD). Methods: A nationwide cohort that included 59,746 boys diagnosed with ADHD and 52,008 healthy subjects retrieved from the National Health Insurance database in Taiwan was also observed between 1999 and 2011. TD was defined by the International Classification of Diseases, 9th revision, Clinical Modifications codes (257.0, 257.1, 257.2, 257.8, or 257.9). Cumulative time of MPH use was categorized into nonuse, short-term use (1-365 days), and long-term use (>365 days). We compared the rate of TD diagnosis between ADHD patients and controls and analyzed the risk of developing a TD after MPH treatment. Results: Compared with the control group (0.06%), the ADHD group had a higher comorbidity rate of TD (0.14%) (adjusted odds ratio [aOR] = 1.95, 95% confidence interval [95% CI]: 1.26-3.04, p = 0.003). However, MPH did not significantly influence the risk of developing TD (adjusted hazard ratio = 1.40, 95% CI: 0.77-2.54, p = 0.272). Compared with ADHD boys without MPH treatment, patients who were prescribed short-term MPH (aOR = 0.96, 95% CI: 0.51-1.82, p = 0.900) and long-term MPH (aOR = 1.40, 95% CI: 0.69-2.83, p = 0.351) showed no significance associated with an increased risk of developing TD. Conclusions: Our nationwide cohort showed that long-term treatment with MPH has no harmful effect on the testosterone function of ADHD patients. However, due to the increased comorbidity rate of ADHD and TD, early recognition and detection of TD in ADHD children have the potential to change the trajectory of TD morbidity later in life.

Methylphenidate alters monoaminergic and metabolic pathways in the cerebellum of adolescent rats

Abnormalities in the cerebellar circuitry have been suggested to contribute to some of the symptoms associated with attention deficit hyperactivity disorder (ADHD). The psychostimulant methylphenidate (MPH) is the major drug for treating this condition. Here, the effects of acute (2.0 mg/kg and 5.0 mg/kg) and chronic (2.0 mg/kg, twice daily for 15 days) MPH treatments were investigated in adolescent (35-40 days old) rats on monoaminergic and metabolic markers in the cerebellum. Data acquired indicates that acute MPH treatment (2.0 mg/kg) decreased cerebellar vesicular monoamine transporter (VMAT2) density, while chronic treatment caused an increase. In contrast, protein levels of tyrosine hydroxylase (TH) and the dopamine D1 receptor were not significantly altered by neither acute nor chronic MPH treatment. In addition, while chronic but not acute MPH treatment significantly enhanced dopamine turnover (DOPAC/dopamine) in the cerebellum, levels of dopamine and homovanillic acid (HVA) were not altered. Acute MPH (5.0 mg/kg) significantly modified levels of a range of cerebellar metabolites with similar trends also detected for the lower dose (2.0 mg/kg). In this regard, acute MPH tended to decrease cerebellar metabolites associated with energy consumption and excitatory neurotransmission including glutamate, glutamine, N-acetyl aspartate, and inosine. Conversely, levels of some metabolites associated with inhibitory neurotransmission, including GABA and glycine were reduced by acute (5.0 mg/kg) MPH, together with acetate, aspartate and hypoxanthine. In conclusion, this study demonstrated that MPH alters cerebellar biochemistry, and that this effect depends on both dose and duration of treatment. The therapeutic significance of these results requires further investigation.

Does Methylphenidate Reduce Testosterone Levels in Humans? A Prospective Study in Children with Attention-Deficit/Hyperactivity Disorder

Background

Animal studies and case reports have suggested that methylphenidate exerts adverse effects on gonadal hormones. This study aimed to determine whether methylphenidate alters testosterone levels in children with attention-deficit/hyperactivity disorder through comparison of those with or without methylphenidate treatment.

Methods

This 4-week, nonrandomized, prospective study conducted in Taiwan included 203 attention-deficit/hyperactivity disorder patients with a mean age of 8.7 years (boys: 75.8%). After the initial recruitment, 137 received daily methylphenidate treatment (medicated group) and 66 were assessed through naturalistic observation (nonmedicated group). The saliva samples of attention-deficit/hyperactivity disorder patients were used to quantify testosterone levels at baseline and the endpoint by using the chemiluminescence immunoassay. At the 4th week, 86 patients in the medicated group and 46 patients in the nonmedicated group were eligible for statistical analyses.

Results

During the study period, salivary testosterone levels did not significantly change in the medicated group (P=.389) or in the nonmedicated group (P=.488). After correction for the potential confounding effects of age and sex, salivary testosterone levels still remained unchanged in the medicated and nonmedicated groups during the 4-week follow-up. In the medicated group, changes in salivary testosterone levels over 4 weeks were not significantly correlated with the methylphenidate daily dose (mean daily dose: 18.1 mg).

Conclusions

Findings suggest that short-term treatment with methylphenidate at usual doses does not significantly alter salivary testosterone levels in attention-deficit/hyperactivity disorder patients. Future studies should clarify whether long-term methylphenidate treatment disrupts testosterone production as well as the function of the reproductive system.

Efeitos do metilfenidato sobre as glândulas salivares maternas de camundongos

Resumo Introdução O metilfenidato (MFD) é um derivado anfetamínico estimulante do sistema nervoso central, que vem sendo cada vez mais consumido pela população mundial, incluindo as mulheres em idade fértil. Ainda não foram estabelecidos os efeitos deste medicamento nas glândulas salivares, durante a gestação. Objetivo Identificar alterações histomorfológicas em glândulas salivares maternas expostas ao metilfenidato. Material e método Para análise histológica, foram utilizadas 32 fêmeas de camundongos Swiss prenhes, distribuídas em um grupo controle e um grupo tratado. A administração foi realizada do quinto ao 17º dia de gestação, via injeção subcutânea; o grupo tratado recebeu 5 mg/kg de metilfenidato, enquanto o grupo controle recebeu o mesmo volume de solução salina estéril. As fêmeas foram eutanasiadas e tiveram suas glândulas salivares removidas e incluídas em parafina para análise em microscopia óptica. Para avaliar a associação entre as variáveis dos grupos, o teste de Kolmogorov-Smirnov e o teste T foram utilizados. Resultado As glândulas parótidas do grupo tratado apresentaram alterações no raio dos ductos e na quantidade de ácinos, quando comparadas às glândulas parótidas do grupo controle. A glândula submandibular do grupo tratado foi a mais afetada: mostrou diferença estatisticamente significativa na espessura da parede dos ductos secretores, no raio dos ductos e no raio dos ácinos, quando comparada à glândula submandibular do grupo controle. A glândula sublingual não apresentou alterações significativas. Conclusão Neste delineamento experimental, o metilfenidato apresentou-se como agente indutor de alterações morfológicas das glândulas salivares, promovendo alterações significativas nos raios de ductos e ácinos das mesmas, sendo a glândula submandibular a mais susceptível a este fármaco.

Prenatal exposure to methylphenidate affects the dopamine system and the reactivity to natural reward in adulthood in rats

BACKGROUND

Methylphenidate (MPH) is a commonly-used medication for the treatment of children with Attention-Deficit/Hyperactivity Disorders (ADHD). However, its prescription to adults with ADHD and narcolepsy raises the question of how the brain is impacted by MPH exposure during pregnancy. The goal of this study was to elucidate the long-term neurobiological consequences of prenatal exposure to MPH using a rat model.

METHODS

We focused on the effects of such treatment on the adult dopamine (DA) system and on the reactivity of animals to natural rewards.

RESULTS

This study shows that adult male rats prenatally exposed to MPH display elevated expression of presynaptic DA markers in the DA cell bodies and the striatum. Our results also suggest that MPH-treated animals could exhibit increased tonic DA activity in the mesolimbic pathway, altered signal-to-noise ratio after a pharmacological stimulation, and decreased reactivity to the locomotor effects of cocaine. Finally, we demonstrated that MPH rats display a decreased preference and motivation for sucrose.

CONCLUSIONS

This is the first preclinical study reporting long-lasting neurobiological alterations of DA networks as well as alterations in motivational behaviors for natural rewards after a prenatal exposure to MPH. These results raise concerns about the possible neurobiological consequences of MPH treatment during pregnancy.

Effects of developmental methylphenidate (MPH) treatment on monoamine neurochemistry of male and female rats

Attention Deficit Hyperactivity Disorder (ADHD) is estimated to affect 4-5% of the adult human population (Kessler et al., 2006; Willcutt, 2012). Often prescribed to attenuate ADHD symptoms (Nair and Moss, 2009), methylphenidate hydrochloride (MPH) can have substantial positive effects. However, there is a paucity of literature regarding its use during pregnancy. Thus, adult women with ADHD face a difficult decision when contemplating pregnancy. In this study, pregnant Sprague-Dawley rats were orally treated a total of 0 (water), 6 (low), 18 (medium), or 42 (high) mg MPH/kg body weight/day (divided into three doses) on gestational days 6-21 (i.e., the low dose received 2 mg MPH/kg body weight 3×/day). Offspring were orally treated with the same daily dose as their dam (divided into two doses) on postnatal days (PNDs) 1-21. One offspring/sex/litter was sacrificed at PND 22 or PND 104 (n=6-7/age/sex/treatment group) and the striatum was quickly dissected and frozen. High Performance Liquid Chromatography (HPLC) coupled to a Photo Diode Array detector (PDA) was used to analyze monoamine content in the striatum of one side while a sandwich ELISA was used to analyze tyrosine hydroxylase (TH) from the other side. Age significantly affected monoamine and metabolite content as well as turnover ratios (i.e., DA, DOPAC, HVA, DOPAC/DA, HVA/DA, 5-HT and 5-HIAA); however, there were no significant effects of sex. Adult rats of the low MPH group had higher DA levels than control adults (p<0.05). At both ages, subjects of the low MPH group had higher TH levels than controls (p<0.05), although neither effect (i.e., higher DA or TH levels) exhibited an apparent dose-response. PND 22 subjects of the high MPH treatment group had higher ratios of HVA/DA and DOPAC/DA than same-age control subjects (p<0.05). The increased TH levels of the low MPH group may be related to the increased DA levels of adult rats. While developmental MPH treatment appears to have some effects on monoamine system development, further studies are required to determine if these alterations manifest as functional changes in behavior.