Orexinergic input to dopaminergic neurons of the human ventral tegmental area

E. Hrabovszky, Csilla S. Molnár, Beáta Á Borsay, Péter Gergely, László Herczeg, Z. Liposits

Research output: Contribution to journalArticle

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Abstract

The mesolimbic reward pathway arising from dopaminergic (DA) neurons of the ventral tegmental area (VTA) has been strongly implicated in reward processing and drug abuse. In rodents, behaviors associated with this projection are profoundly influenced by an orexinergic input from the lateral hypothalamus to the VTA. Because the existence and significance of an analogous orexigenic regulatory mechanism acting in the human VTA have been elusive, here we addressed the possibility that orexinergic neurons provide direct input to DA neurons of the human VTA. Dual-label immunohistochemistry was used and orexinergic projections to the VTA and to DA neurons of the neighboring substantia nigra (SN) were analyzed comparatively in adult male humans and rats. Orexin B-immunoreactive (IR) axons apposed to tyrosine hydroxylase (TH)-IR DA and to non-DA neurons were scarce in the VTA and SN of both species. In the VTA, 15.0±2.8% of TH-IR perikarya in humans and 3.2±0.3% in rats received orexin B-IR afferent contacts. On average, 0.24±0.05 and 0.05±0.005 orexinergic appositions per TH-IR perikaryon were detected in humans and rats, respectively. The majority (86-88%) of randomly encountered orexinergic contacts targeted the dendritic compartment of DA neurons. Finally, DA neurons of the SN also received orexinergic innervation in both species. Based on the observation of five times heavier orexinergic input to TH-IR neurons of the human, compared with the rat, VTA, we propose that orexinergic mechanism acting in the VTA may play just as important roles in reward processing and drug abuse in humans, as already established well in rodents.

Original languageEnglish
Article numbere83029
JournalPLoS One
Volume8
Issue number12
DOIs
Publication statusPublished - Dec 20 2013

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Ventral Tegmental Area
Dopaminergic Neurons
Neurons
tyrosine 3-monooxygenase
neurons
Tyrosine 3-Monooxygenase
Rats
Substantia Nigra
Reward
drug abuse
rats
Substance-Related Disorders
rodents
Rodentia
Lateral Hypothalamic Area
innervation
hypothalamus
Processing
axons
Pharmaceutical Preparations

ASJC Scopus subject areas

  • Agricultural and Biological Sciences(all)
  • Biochemistry, Genetics and Molecular Biology(all)
  • Medicine(all)

Cite this

Orexinergic input to dopaminergic neurons of the human ventral tegmental area. / Hrabovszky, E.; Molnár, Csilla S.; Borsay, Beáta Á; Gergely, Péter; Herczeg, László; Liposits, Z.

In: PLoS One, Vol. 8, No. 12, e83029, 20.12.2013.

Research output: Contribution to journalArticle

Hrabovszky, E. ; Molnár, Csilla S. ; Borsay, Beáta Á ; Gergely, Péter ; Herczeg, László ; Liposits, Z. / Orexinergic input to dopaminergic neurons of the human ventral tegmental area. In: PLoS One. 2013 ; Vol. 8, No. 12.
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