Effect of Methylphenidate on the onset of puberty and reproductive organ development in rats

Puberty and ADHD: A scoping review and framework for future research

Individuals with ADHD may experience puberty differently from their peers, which has implications for their health and wellbeing. This scoping review characterised and summarised literature reporting quantitative analyses of puberty and ADHD. To identify studies, nine databases (MEDLINE Complete, Web of Science, Embase, PsycInfo, ERIC, CENTRAL, PsycExtra, WHO ICTRP, and ProQuest Dissertations & Theses) were searched using key terms related to puberty/pubertal hormones and ADHD/ADHD traits. From 2795 initial records, 89 studies were eligible. Relevant analyses in included studies were categorised under five topics: 1) pubertal group comparisons between participants with ADHD and control participants; 2) associations between puberty and ADHD; 3) prevalence of ADHD in atypical puberty conditions; 4) ADHD medication effects on puberty; and 5) puberty and co-occurring psychological conditions. With some exceptions, summarised findings for each topic were generally inconsistent, indicating further well-planned primary studies are needed. A framework for future research is provided, recommending methodological improvements, including use of approaches that capture the complexities of puberty and ADHD, more inclusive sampling, and employing theories/models that recognise dynamics between puberty, psychological, social, and other biological factors. Additionally, it is recommended that research priorities in this area are identified in collaboration with key stakeholders, especially the ADHD community.

The effect of methylphenidate on the reproductive function of female rats

AIM

Research on the effects of methylphenidate on female fertility is limited. This study evaluated the effects of methylphenidate on reproductive function, oxidants, antioxidants, proinflammatory cytokines, prolactin, and cortisol in female rats.

METHODS

Forty-eight albino Wistar female rats were divided into four groups consisting of 12 rats, which were given pure water orally once daily for 7 days (HG-1), 10 mg/kg methylphenidate orally once daily for 7 days (MP-1), pure water orally once daily for 30 days (HG-2), and 10 mg/kg methylphenidate orally once daily for 30 days (MP-2). At the end of the treatment periods, tail vein blood was collected from six rats per group for prolactin and cortisol determination. Subsequently, euthanasia was performed and the ovaries were removed. Ovaries were analyzed for malondialdehyde (MDA), total glutathione (tGSH), superoxide dismutase (SOD), catalase (CAT), interleukin-1 beta (IL-1β), and tumor necrosis factor-alpha (TNF-α), and immunohistochemically. For breeding, the remaining six rats were mated with male rats for 1 month. Rats that failed to give birth were classed as infertile.

RESULTS

A comparison of MP-1 and MP-2 groups to healthy controls revealed an elevation in MDA and corticosterone levels, and a decline in tGSH, SOD, and CAT levels (p < 0.001). Methylphenidate did not affect prolactin, IL-1β, and TNF-α levels (p > 0.05). MP-1 and MP-2 exhibited immunopositivity for 8-hydroxy-2'-deoxyguanosine (8-OHDG). MP-2 rats developed 66.7% infertility while MP-1, HG-1, and HG-2 rats did not.

CONCLUSION

In ovaries, methylphenidate caused oxidative stress, but did not induce inflammation. Long-term use of methylphenidate caused increased cortisol levels and infertility.

Disorders of puberty and neurodevelopment: A shared etiology?

The neuroendocrine control of puberty and reproduction is fascinatingly complex, with up- and down-regulation of key reproductive hormones during fetal, infantile, and later childhood periods that determine the correct function of the hypothalamic-pituitary-gonadal axis and the timing of puberty. Neuronal development is a vital element of these processes, and multiple conditions of disordered puberty and reproduction have their etiology in abnormal neuronal migration or function. Although there are numerous documented cases across multiple conditions wherein patients have both neurodevelopmental disorders and pubertal abnormalities, this has mostly been described ad hoc and the associations are not clearly documented. In this review, we aim to describe the overlap between these two groups of conditions and to increase awareness to ensure that puberty and reproductive function are carefully monitored in patients with neurodevelopmental conditions, and vice versa. Moreover, this commonality can be explored for clues about the disease mechanisms in these patient groups and provide new avenues for therapeutic interventions for affected individuals.

ADHD and Risk of Precocious Puberty: Considering the Impact of MPH

BACKGROUND/OBJECTIVES

The complex association between attention-deficit/hyperactivity disorder (ADHD) and methylphenidate (MPH) with precocious puberty (PP) is still unclear. This study aims to investigate the association between ADHD, MPH, and PP.

METHODS

This is a nationwide cohort study including a total of 3,342,077 individuals, 186,681 with ADHD and 3,155,396 without. First, we compared the risk of PP between ADHD cases and non-ADHD cases. Second, we compared the risk of PP between MPH users and non-MPH users in patients with ADHD.

RESULTS

Patients with ADHD were at a greater risk of PP (adjusted hazard ratio [aHR], 2.01 [95% CI, 1.91-2.11]). In our moderation analyses, the female gender was a positive additive effect modifier of the association between ADHD and PP, whereas tics and intellectual disability were negative effect modifiers. In patients with ADHD, MPH users had a significantly lower risk of PP (aHR, 0.63 [95% CI 0.57-0.70]), and females had a negative effect modification on the association between MPH and PP.

CONCLUSIONS

Our study found that children with ADHD were at a greater risk of PP. Girls with ADHD were a group particularly vulnerable to PP. Comorbid tics or intellectual disability was associated with a lower risk of PP. Among patients with ADHD, MPH was protective against PP, especially in girls. However, these preliminary results need further validation due to the nature of them being from an electronic database study. Unmeasured confounding factors might affect the association between MPH and PP.

The Impact of Methylphenidate on Pubertal Maturation and Bone Age in ADHD Children and Adolescents: Results from the ADHD Drugs Use Chronic Effects (ADDUCE) Project

OBJECTIVE

The short-term safety of methylphenidate (MPH) has been widely demonstrated; however the long-term safety is less clear. The aim of this study was to investigate the safety of MPH in relation to pubertal maturation and to explore the monitoring of bone age.

METHOD

Participants from ADDUCE, a two-year observational longitudinal study with three parallel cohorts (MPH group, no-MPH group, and a non-ADHD control group), were compared with respect to Tanner staging. An Italian subsample of medicated-ADHD was further assessed by the monitoring of bone age.

RESULTS

The medicated and unmedicated ADHD groups did not differ in Tanner stages indicating no higher risk of sexual maturational delay in the MPH-treated patients. The medicated subsample monitored for bone age showed a slight acceleration of the bone maturation after 24 months, however their predicted adult height remained stable.

CONCLUSION

Our results do not suggest safety concerns on long-term treatment with MPH in relation to pubertal maturation and growth.

Postweaning Social Isolation Alters Puberty Onset by Suppressing Electrical Activity of Arcuate Kisspeptin Neurons

INTRODUCTION

Postweaning social isolation (PWSI) in rodents is an advanced psychosocial stress model in early life. Some psychosocial stress, such as restrain and isolation, disrupts reproductive physiology in young and adult periods. Mechanisms of early-life stress effects on central regulation of reproduction need to be elucidated. We have investigated the effects of PWSI on function of arcuate kisspeptin (ARCKISS1) neurons by using electrophysiological techniques combining with monitoring of puberty onset and estrous cycle in male and female Kiss1-Cre mice.

METHODS

Female mice were monitored for puberty onset with vaginal opening examination during social isolation. After isolation, the estrous cycle of female mice was monitored with vaginal cytology. Anxiety-like behavior of mice was determined by an elevated plus maze test. Effects of PWSI on electrophysiology of ARCKISS1 neurons were investigated by the patch clamp method after intracranial injection of AAV-GFP virus into arcuate nucleus of Kiss1-Cre mice after the isolation period.

RESULTS

We found that both male and female isolated mice showed anxiety-like behavior. PWSI caused delay in vaginal opening and extension in estrous cycle length. Spontaneous-firing rates of ARCKISS1 neurons were significantly lower in the isolated male and female mice. The peak amplitude of inhibitory postsynaptic currents to ARCKISS1 neurons was higher in the isolated mice, while frequency of excitatory postsynaptic currents was higher in group-housed mice.

CONCLUSION

These findings demonstrate that PWSI alters pre- and postpubertal reproductive physiology through metabolic and electrophysiological pathways.