1. Academic Validation
  2. Droxidopa alters dopamine neuron and prefrontal cortex activity and improves attention-deficit/hyperactivity disorder-like behaviors in rats

Droxidopa alters dopamine neuron and prefrontal cortex activity and improves attention-deficit/hyperactivity disorder-like behaviors in rats

  • Eur J Pharmacol. 2021 Feb 5;892:173826. doi: 10.1016/j.ejphar.2020.173826.
Ike Dela Peña 1 Guofang Shen 2 Wei-Xing Shi 3
Affiliations

Affiliations

  • 1 Department of Pharmaceutical and Administrative Sciences, Loma Linda University School of Pharmacy, Loma Linda, CA, 92350, USA. Electronic address: idelapena@llu.edu.
  • 2 Department of Pharmaceutical and Administrative Sciences, Loma Linda University School of Pharmacy, Loma Linda, CA, 92350, USA.
  • 3 Department of Pharmaceutical and Administrative Sciences, Loma Linda University School of Pharmacy, Loma Linda, CA, 92350, USA; Department of Basic Sciences, Loma Linda University School of Medicine, Loma Linda, CA, 92350, USA.
Abstract

Finding alternative treatments for attention-deficit/hyperactivity disorder (ADHD) is crucial given the safety and efficacy problems of current ADHD medications. Droxidopa, also known as L-threo-dihydroxyphenylserine (L-DOPS), is a norepinephrine prodrug that enhances brain norepinephrine and dopamine levels. In this study, we used electrophysiological tests to examine effects of L-DOPS on the prefrontal cortex (PFC) and dopamine neurons in the ventral tegmental area. We also conducted behavioral tests to assess L-DOPS' effects on ADHD-like behaviors in rats. In chloral hydrate-anesthetized rats, PFC local field potentials oscillated between the active, depolarized UP state and the hyperpolarized DOWN state. Mimicking the effect of d-amphetamine, L-DOPS, given after the peripheral amino acid decarboxylase inhibitor, benserazide (BZ), increased the amount of time the PFC spent in the UP state, indicating an excitatory effect of L-DOPS on PFC neurons. Like d-amphetamine, L-DOPS also inhibited dopamine neurons, an effect significantly reversed by the D2-like receptor antagonist raclopride. In the behavioral tests, BZ + L-DOPS improved hyperactivity, inattention and impulsive action of the adolescent spontaneously hypertensive rat (SHR/NCrl), well-validated animal model of the combined type of ADHD. BZ + L-DOPS also reduced impulsive choice and impulsive action of Wistar rats, but did not ameliorate the inattentiveness of Wistar Kyoto rats (WKY/NCrl), proposed model of the ADHD-predominantly inattentive type. In conclusion, L-DOPS produced effects on the PFC and dopamine neurons characteristic of drugs used to treat ADHD. BZ + L-DOPS ameliorated ADHD-like behaviors in rats suggesting its potential as an alternative ADHD treatment.

Keywords

ADHD; Animal models; Dopamine; Droxidopa; L-DOPS; Norepinephrine; SHR/NCrl.

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