Does Methylphenidate Affect Cystometric Parameters in Spontaneously Hypertensive Rats?

Neurochemical Effects of Methylphenidate and Modafinil in Ameliorating Stress-Induced Cognitive Deficits

PURPOSE

Chronic stressful situations result in altered monoaminergic activity of neurotransmitters, resulting in various conditions characterized by deficits in learning, memory and attention. Stimulant effects can be visualized in terms of increased cognitive abilities through enhancement of dopamine (DA) release.

METHOD

This study examined cognitive responses and brain DA and 5-hydroxytryptamine (5HT) levels after prolonged methylphenidate (MPH) and modafinil administration, to demonstrate their effect on stress-induced cognitive deficits in rats. Effects on cognition were evaluated by passive avoidance and water maze tests. Furthermore brain levels of DA, homovanillic acid (HVA), dihydroxyphenylacetic acid (DOPAC), 5HT and 5-hydroxyindoleacetic acid (5HIAA) were analyzed by high-performance liquid chromatography coupled with electrochemical detection.

RESULTS

We found that both MPH and modafinil improved cognition in both restrained and unrestrained rats, as examined through water maze and passive avoidance tests. Furthermore, these substance were associated with increased brain DA and 5-HT levels. Notabily, we observed decrease in DOPAC and HVA levels, while 5-HIAA levels exhibited a slight increase.

CONCLUSIONS

The prevention of stress-induced cognitive deficits by MPH and modafinil could be elucidated through the interaction between 5HT and DA in regulating cognitive function.

Effects of methylphenidate on the lower urinary tract in patients with attention deficit hyperactivity disorder and without voiding dysfunction

BACKGROUND

Attention deficit hyperactivity disorder (ADHD) is characterised by a range of symptoms, such as excessive mobility, difficulty in maintaining attention and inadequate impulse control. Methylphenidate (MPH) is widely prescribed as a treatment for ADHD. In the literature, studies investigating the effects of MPH on the lower urinary tract (LUT) are limited.

OBJECTIVE

The aim of the study was to evaluate MPH-induced LUT symptoms (LUTSs) in patients with ADHD without a diagnosis of voiding dysfunction (VD).

STUDY DESIGN

After ethical committee approval, volunteers aged 7-17 y were divided into two groups, with group 1 composed of individuals diagnosed with ADHD but not VD and group 2 (control) composed of healthy individuals. Lower urinary tract symptoms and quality of life, in addition to uroflowmetry test results and postvoiding residual volume (PVRV), were evaluated in both groups at baseline and again 4 wk later. The individuals in group 1 were treated with MPH after baseline screening. The dysfunctional voiding scoring system questionnaire was used for scoring LUTSs. Postvoiding residual volume was measured by ultrasound. Bladder capacity (BC) was calculated as the sum of voided volume (VV) and PVRV. The means of the maximum flow rate (Q max), mean flow rate (Q mean), VV, PVRV and BC were recorded.

RESULTS

After exclusions, there were 43 participants in group 1 and 39 participants in group 2. There was no significant difference between the mean age of groups (p = 0.727). Compared with the baseline, VV and BC increased significantly in group 1 (p = 0.001 and p = 0.002, respectively) at the 4-wk follow-up. There was no significant difference in these parameters in group 2.

DISCUSSION

This study demonstrated that VV and BC increased after MPH treatment in patients with ADHD without a diagnosis of VD. The mechanism underlying this effect is unclear, but it may be associated with dopaminergic and noradrenergic effects.

CONCLUSION

The findings of the present study can inform further studies on the mechanism underlying the effect of MPH on the LUT. In a future study, the authors suggest evaluating the effects of MPH in a urodynamic study in patients with ADHD diagnosed with VD.

Haloperidol attenuates Methylphenidate and Modafinil induced behavioural sensitization and cognitive enhancement

Previous studies have demonstrated that repeated psychostimulant administration produces behavioural sensitization and cognitive tolerance. Brain dopaminergic system and the involvement of dopamine D₂-receptors are considered to be important in psychostimulant-induced sensitization. Study designed to compared the motor activity by using familiar and novel enviroments and cognitive effects by water maze and passive avoidance test after long term administration of methylphenidate(at the dose 0.6 mg/kg/day, 2.5 mg/kg/day and 10 mg/kg/day) and modafinil (50 mg/kg/day, 64 mg/kg/day and 75 mg/kg/day) in rats. The effects of challenge dose of haloperidol (at the dose of 1 mg/kg i.p.) has monitored to visualize any subsensitization or supersensitization of D₂ receptors. We found that motor activity and cognitive performance was increased in all doses and sensitization effect was more pronounced after 13 days of drug administration were greater at high than low and medium doses.Challenge dose of haloperidol attenuate motor activity in familiar and novel environment and impaired cognition in water maze and passive avoidance test in all treated rats. The effect of Haloperidol in high dose treated rats were however somewhat greater than low and medium dose treated rats following methylphenidate and modafinil administration. Increased response of haloperidol in methylphenidate treated rats can be explained in term of supersensitization of D₂ receptors which is greater in high dose treated rats. The results show that the role of D₂ receptors to develop side effects such as behavioural sensitization and cognitive tolerance by the long term administration of psychostimulants is of sufficient importance and helpful in understanding the mechanisms underlying the undesirable effects of psychostimulants.

Differential perturbation of the interstitial cystitis-associated genes of bladder and urethra in rat model

Interstitial cystitis (IC) is a chronic bladder dysfunction characterized as urinary frequency, urgency, nocturia, and pelvic pain. The changes in urethra may wind up with the bladder changes in structure and functions, however, the functions of the urethra in IC remains elusive. The aim of this study was to understand the perturbed gene expression in urethra, compared with urinary bladder, associated with the defected urodynamics. Using female IC mimic rats, a comprehensive RNA-sequencing combined with a bioinformatics analysis was performed and revealed that IC-specific genes in bladder or urethra. Gene ontology analysis suggested that the cell adhesion or extracellular matrix regulation, intracellular signaling cascade, cardiac muscle tissue development, and second messenger-mediated signaling might be the most enriched cellular processes in IC context. Further study of the effects of these bladder- or urethra-specific genes may suggest underlying mechanism of lower urinary tract function and novel therapeutic strategies against IC.