Expression of the dopamine transporter in the brain of the honeybee, Apis mellifera L. (Hymenoptera: Apidae)

Attention deficit hyperactivity disorder (ADHD) is believed to be connected with a high level of hyperactivity caused by alterations of the control of dopaminergic transmission in the brain. The strain of hyperdopaminergic dopamine transporter knockout (DAT-KO) rats represents an optimal model for investigating ADHD-related pathological mechanisms. The goal of this work was to study the influence of the overactivated dopamine system in the brain on a motor cognitive task fulfillment. The DAT-KO rats were trained to learn an object recognition task and store it in long-term memory. We found that DAT-KO rats can learn to move an object and retrieve food from the rewarded familiar objects and not to move the non-rewarded novel objects. However, we observed that the time of task performance and the distances traveled were significantly increased in DAT-KO rats in comparison with wild-type controls. Both groups of rats explored the novel objects longer than the familiar cubes. However, unlike controls, DAT-KO rats explored novel objects significantly longer and with fewer errors, since they preferred not to move the non-rewarded novel objects. After a 3 months’ interval that followed the training period, they were able to retain the learned skills in memory and to efficiently retrieve them. The data obtained indicate that DAT-KO rats have a deficiency in learning the cognitive task, but their hyperactivity does not prevent the ability to learn a non-spatial cognitive task under the presentation of novel stimuli. The longer exploration of novel objects during training may ensure persistent learning of the task paradigm. These findings may serve as a base for developing new ADHD learning paradigms.

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Post-Illumination Pupil Response as a Biomarker for Cognition in α-Synucleinopathies

Journal of Parkinson s Disease ◽

10.3233/jpd-212775 ◽

2021 ◽

pp. 1-6

Author(s):

Oliver Steiner ◽

Jan de Zeeuw ◽

Sophia Stotz ◽

Frederik Bes ◽

Dieter Kunz

Keyword(s):

Executive Functioning ◽

Dopamine Transporter ◽

Rem Sleep ◽

Rem Sleep Behavior Disorder ◽

Behavior Disorder ◽

Cognitive State ◽

Neurocognitive Disorder ◽

Sleep Behavior ◽

Cognitive Domains ◽

The Brain

Neurodegenerative processes in the brain are reflected by structural retinal changes. As a possible biomarker of cognitive state in prodromal α-synucleinopathies, we compared melanopsin-mediated post-illumination pupil responses (PIPR) with cognition (CERAD-plus) in 69 patients with isolated REM-sleep behavior disorder. PIPR was significantly correlated with cognitive domains, especially executive functioning (r = 0.417, p < 0.001), which was more pronounced in patients with lower dopamine-transporter density, suggesting advanced neurodegenerative state (n = 26; r = 0.575, p = 0.002). Patients with mild neurocognitive disorder (n = 10) had significantly reduced PIPR (smaller melanopsin-mediated response) compared to those without (p = 0.001). Thus, PIPR may be a functional—possibly monitoring—marker for impaired cognitive state in (prodromal) α-synucleinopathies.

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