Consequences of manganese intoxication on the circadian rest-activity rhythms in the rat

Safa Bouabid, Karim Fifel, Abdelhamid Benazzouz, Nouria Lakhdar-Ghazal

Research output: Contribution to journalArticle

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Abstract

Manganese (Mn) intoxication is associated with neurological dysfunctions collectively known as Parkinsonism or Manganism. Like in Parkinson's disease, Manganism is associated with motor disturbances, together with non-motor symptoms including cognitive and neuropsychiatric deficits. Although sleep dysfunctions are commonly reported among workers exposed to Mn, their underlying pathophysiology remains unknown. In this study, we investigated the rest-activity rhythms in rats treated daily with MnCl2 (10 mg/kg, i.p) for 5 weeks. Locomotor activity was assessed under a light–dark (LD) cycle, constant darkness (DD) and during adjustment to 6 h shifts of the LD cycle. In LD conditions, Mn-treated rats exhibited a more fragmented and less stable rest-activity rhythm in addition to a reduction in the total 24-h amount of locomotor activity as well as in the activity confined to the active dark phase of the LD. Consequently, a significant decrease in the amplitude of the rest-activity rhythm was observed. These disturbances were displayed during and after Mn treatment. Furthermore, after the 6-h phase advance of the LD cycle, Mn-treated rats failed to re-adjust accurately their behavioral activity to the new shifted LD cycle. Upon release from LD into DD, Mn-treated rats expressed a normal and stable free-running period of their rest-activity rhythm (23.92 ± 0.07 h in Mn group vs. 24.01 ± 0.04 h in control rats). However, their rest-activity rhythm remained highly fragmented and less stable. Our results provide the first evidence that chronic Mn intoxication leads to impairment of rest-activity rhythms in addition to the motor and non-motor disturbances reported in Manganism.

Original languageEnglish (US)
Pages (from-to)13-23
Number of pages11
JournalNeuroscience
Volume331
DOIs
StatePublished - Sep 7 2016

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Manganese
Locomotion
Social Adjustment
Neurobehavioral Manifestations
Darkness
Parkinsonian Disorders
Parkinson Disease
Sleep

All Science Journal Classification (ASJC) codes

  • Neuroscience(all)

Cite this

Consequences of manganese intoxication on the circadian rest-activity rhythms in the rat. / Bouabid, Safa; Fifel, Karim; Benazzouz, Abdelhamid; Lakhdar-Ghazal, Nouria.

In: Neuroscience, Vol. 331, 07.09.2016, p. 13-23.

Research output: Contribution to journalArticle

Bouabid, Safa ; Fifel, Karim ; Benazzouz, Abdelhamid ; Lakhdar-Ghazal, Nouria. / Consequences of manganese intoxication on the circadian rest-activity rhythms in the rat. In: Neuroscience. 2016 ; Vol. 331. pp. 13-23.
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