Dataset Information

The alpha-2A adrenoceptor agonist guanfacine improves sustained attention and reduces overactivity and impulsiveness in an animal model of Attention-Deficit/Hyperactivity Disorder (ADHD).

ABSTRACT:

Background

ADHD is currently defined as a cognitive/behavioral developmental disorder where all clinical criteria are behavioral. Overactivity, impulsiveness, and inattentiveness are presently regarded as the main clinical symptoms. There is no biological marker, but there is considerable evidence to suggest that ADHD behavior is associated with poor dopaminergic and noradrenergic modulation of neuronal circuits that involve the frontal lobes. The best validated animal model of ADHD, the Spontaneously Hypertensive Rat (SHR), shows pronounced overactivity, impulsiveness, and deficient sustained attention. While dopamine release is decreased in SHR prefrontal cortex, norepinephrine concentrations are elevated. The noradrenergic system appears to be hyperactive as a result of impaired alpha-2A adrenoceptor regulation. Thus, the present study tested behavioral effects of the centrally acting alpha-2A adrenoceptor agonist guanfacine on SHR behavior.

Methods

The present study tested behavioral effects of guanfacine at doses of 0.075, 0.15, 0.30 and 0.60 mg base/kg i.p. in both male SHRs and their controls, the Wistar Kyoto rat (WKY). ADHD-like behavior was tested with a visual discrimination task measuring overactivity, impulsiveness and inattentiveness.

Results

The striking impulsiveness, overactivity, and reduced sustained attention during baseline conditions in the SHR improved by treatment with guanfacine. The most pronounced improvement in SHR behavior was seen following the two highest doses (0.3 and 0.6 mg/kg) of guanfacine when SHR behaviors virtually normalized. The positive effects of the drug were most marked towards the end of the session.

Conclusion

The results indicate that guanfacine improved poor noradrenergic modulation of neuronal circuits that involve the frontal lobes in an animal model of ADHD. The present results support the beneficial effects of guanfacine on ADHD behavior reported clinically and experimentally in primate models of frontal function. It is likely that guanfacine improved prefrontal functions in the SHR. It cannot be concluded, however, that the effects of the drug are mediated solely by norepinephrine.

SUBMITTER: Sagvolden T

PROVIDER: S-EPMC1764416 | biostudies-literature | 2006 Dec

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

The alpha-2A adrenoceptor agonist guanfacine improves sustained attention and reduces overactivity and impulsiveness in an animal model of Attention-Deficit/Hyperactivity Disorder (ADHD).

Sagvolden Terje T

Behavioral and brain functions : BBF 20061215

<h4>Background</h4>ADHD is currently defined as a cognitive/behavioral developmental disorder where all clinical criteria are behavioral. Overactivity, impulsiveness, and inattentiveness are presently regarded as the main clinical symptoms. There is no biological marker, but there is considerable evidence to suggest that ADHD behavior is associated with poor dopaminergic and noradrenergic modulation of neuronal circuits that involve the frontal lobes. The best validated animal model of ADHD, the ...[more]

PMID: 17173664

Similar Datasets

Project description:BackgroundADHD is currently defined as a cognitive/behavioral developmental disorder where all clinical criteria are behavioral. Overactivity, impulsiveness, and inattentiveness are presently regarded as the main clinical symptoms. There is no biological marker, but there is considerable evidence to suggest that ADHD behavior is associated with poor dopaminergic and noradrenergic modulation of neuronal circuits that involve the frontal lobes. The best validated animal model of ADHD, the Spontaneously Hypertensive Rat (SHR), shows pronounced overactivity, impulsiveness, and deficient sustained attention. While dopamine release is decreased in SHR, norepinephrine concentrations are elevated. The primary objective of the present research was to test effects of a range of doses of the catecholamine agonists d- and l-amphetamine on ADHD-like symptoms in SHR.MethodsThe present study tested behavioral effects of 0.64 to 1.91 mg/kg d-amphetamine; and 1.27 to 3.81 mg/kg l-amphetamine base/kg i.p. in male SHRs and their controls, the Wistar Kyoto rat (WKY). ADHD-like behavior was tested with a visual discrimination task measuring overactivity, impulsiveness and inattentiveness.ResultsThe striking impulsiveness, overactivity, and poorer sustained attention during baseline conditions in the SHR were improved by treatment with the amphetamine isomers. The dose-response curves were, however, different for the different behaviors. Most significantly, d-amphetamine reduced overactivity and impulsiveness more efficiently than comparable doses of l-amphetamine. The lowest dose of d-amphetamine and low-to-medium doses of l-amphetamine improved sustained attention. The highest dose of d-amphetamine used interfered with SHR behavior. A second study showed that the impaired sustained attention (percent correct lever choice) in the SHR was not due to impaired visual functions or poorer working memory.DiscussionThe present results indicate that overactivity and impulsiveness may to some extent be associated with imbalances in neural circuits that differ from those causing poor sustained attention and that the two amphetamine isomers may affect the different neuromodulators differently. While d-amphetamine improved SHR overactivity, impulsiveness as well as sustained attention, the behavioral effects of l-amphetamine were relatively more specific for improving sustained attention than for the other 2 symptoms. Thus, while d- and l-amphetamine affect similar neuronal systems their relative potencies may be different.

Project description:While psychiatric comorbidities of attention-deficit/hyperactivity disorder (ADHD) have been extensively explored, less attention has been paid to somatic conditions possibly associated with this disorder. However, mounting evidence in the last decade pointed to a possible significant association between ADHD and certain somatic conditions, including obesity. This papers provides an update of a previous systematic review on the relationship between obesity and ADHD (Cortese and Vincenzi, Curr Top Behav Neurosci 9:199-218, 2012), focusing on pertinent peer-reviewed empirical papers published since 2012. We conducted a systematic search in PubMed, Ovid, and Web of Knowledge databases (search dates: from January 1st, 2012, to July 16th, 2016). We retained a total of 41 studies, providing information on the prevalence of obesity in individuals with ADHD, focusing on the rates of ADHD in individuals with obesity, or reporting data useful to gain insight into possible mechanisms underlying the putative association between ADHD and obesity. Overall, over the past 4 years, an increasing number of studies have assessed the prevalence of obesity in individuals with ADHD or the rates of ADHD in patients with obesity. Although findings are mixed across individual studies, meta-analytic evidence shows a significant association between ADHD and obesity, regardless of possible confounding factors such as psychiatric comorbidities. An increasing number of studies have also addressed possible mechanisms underlying the link between ADHD and obesity, highlighting the role, among others, of abnormal eating patterns, sedentary lifestyle, and possible common genetic alterations. Importantly, recent longitudinal studies support a causal role of ADHD in contributing to weight gain. The next generation of studies in the field should explore if and to which extent the treatment of comorbid ADHD in individuals with obesity may lead to long-term weight loss, ultimately improving their overall well-being and quality of life.

Project description:ObjectiveBecause models of attention-deficit/hyperactivity disorder (ADHD) therapeutics emphasize benefits of both enhanced dopaminergic and noradrenergic signaling, strategies to enhance D1 and α2A agonism may yield enhanced clinical and cognitive responses. This study tested the hypothesis that combined effects of a dopamine and noradrenergic agonist, d-methylphenidate extended-release (DMPH) with guanfacine (GUAN), an α2A receptor agonist, would be clinically superior to either monotherapy and would have equal tolerability.MethodAn 8-week, double-blind, 3-arm, comparative trial randomized 7- to 14-year-olds with DSM-IV ADHD to GUAN (1-3 mg/day), DMPH (5-20 mg/day), or a combination (COMB) with fixed-flexible dosing. Outcome measures were the ADHD Rating Scale IV (ADHD-RS-IV) and the Clinical Global Impression-Improvement (CGI-I) scale. Data on adverse events and safety measures were obtained.ResultsA total of 207 participants were randomized and received drug. Analyses showed significant treatment group main effects for ADHD-RS-IV ADHD total (p = .0001) and inattentive symptoms (p = .0001). COMB demonstrated small but consistently greater reductions in ADHD-RS-IV Inattentive subscale scores versus monotherapies (DMPH: p = .05; f(2) = .02; and GUAN: p = .02; f(2) = .02), and was associated with a greater positive response rate by CGI-I (p = .01). No serious cardiovascular events occurred. Sedation, somnolence, lethargy, and fatigue were greater in both guanfacine groups. All treatments were well tolerated.ConclusionCOMB showed consistent evidence of clinical benefits over monotherapies, possibly reflecting advantages of greater combined dopaminergic and α2A agonism. Adverse events were generally mild to moderate, and COMB treatment showed no differences in safety or tolerability.Clinical trial registration informationSingle Versus Combination Medication Treatment for Children With Attention Deficit Hyperactivity Disorder (Project1); http://clinicaltrials.gov/; NCT00429273.

Dataset Information

The alpha-2A adrenoceptor agonist guanfacine improves sustained attention and reduces overactivity and impulsiveness in an animal model of Attention-Deficit/Hyperactivity Disorder (ADHD).

Background

Methods

Results

Conclusion

Publications

The alpha-2A adrenoceptor agonist guanfacine improves sustained attention and reduces overactivity and impulsiveness in an animal model of Attention-Deficit/Hyperactivity Disorder (ADHD).

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets