Elsevier

Neuroscience

Volume 164, Issue 2, 1 December 2009, Pages 404-414
Neuroscience

Behavioural Neuroscience
Research Paper
GABA in pedunculopontine tegmentum increases rapid eye movement sleep in freely moving rats: possible role of GABA-ergic inputs from substantia nigra pars reticulata

https://doi.org/10.1016/j.neuroscience.2009.08.025Get rights and content

Abstract

Pedunculopontine tegmentum (PPT) has GABA-ergic neurons and receives GABA-ergic projections from substantia nigra pars reticulata (SNrpr). Based on the recent studies from our and other laboratories, it was hypothesized that GABA in PPT promotes rapid eye movement (REM) sleep. In order to further study the role of GABA in PPT in REM sleep regulation, we microinjected GABA-A agonist, muscimol (200 nL, 3.5 mM), into the PPT. Muscimol in PPT significantly enhanced the amount of REM sleep by increasing the mean number of REM sleep bouts. Besides the local interneurons, GABA-ergic afferents from SNrpr are another source of GABA in PPT. In order to understand the contribution of GABA-ergic inputs from SNrpr into PPT for REM sleep regulation, SNrpr was electrically stimulated either alone or simultaneously along with the infusion of GABA-A antagonist, picrotoxin (200 nL, 0.86 mM), into the PPT. The experiment was designed with the premise that stimulation of SNrpr should increase GABA levels in PPT which should increase REM sleep comparable to that after muscimol microinjection in PPT. Further, the effect of stimulation of SNrpr on REM sleep should be antagonized by simultaneous infusion of picrotoxin into PPT. The electrical stimulation of SNrpr did not produce any significant change in sleep–wake states although it was sufficient to counter the effect of picrotoxin injection into the PPT. To overcome the limitations and confounds of electrical stimulation, SNrpr was pharmacologically stimulated by glutamate microinjection (200 nL, 5.34 mM). Infusion of glutamate into SNrpr enhanced REM sleep by increasing the mean number of REM sleep bouts, which was similar and comparable to the effect of muscimol injection into the PPT. The results confirm that GABA in PPT either from local neurons or from SNrpr promotes REM sleep.

Section snippets

Experimental procedures

The experiments were conducted on chronically implanted freely moving male Wistar rats (n=18) weighing 280–320 g. The rats were maintained at 12:12 light:dark cycle (lights on at 7:00 am) with food and water ad libitum. Experiments were conducted in accordance with the National Institutes of Health guidelines for the care and use of laboratory animals and the experiments were approved by the Institutional Animal Ethics Committee. Utmost care was taken to use a minimum number of animals

Effect of muscimol microinjection into the PPT

The sites where muscimol injections produced (effective sites) or did not produce (ineffective sites) increase in REM sleep are shown in Fig. 2A. The site of microinjection into PPT was confirmed by the presence of cannula track and Pontamine Sky Blue dye spots amidst ChAT-immunopositive cholinergic neurons of PPT (Fig. 2B, C). Three out of five rats had the microinjection sites within the boundary of PPT. Microinjection of muscimol into PPT enhanced REM sleep (F(2,3)=19.39, P<0.01 compared to

Discussion

We observed that facilitation of GABA-ergic transmission in PPT either by local muscimol microinjection or by pharmacological activation of SNrpr increased the total time spent in REM sleep in freely moving rats. These observations are in agreement with previous reports from others (Torterolo et al 2001, Torterolo et al 2002) and our study in which we proposed a REM sleep promoting role for GABA in PPT (Pal and Mallick, 2006). However, a previous study in decerebrate cats postulated an

Conclusion

The results obtained in this study show that GABA in PPT promotes REM sleep and that the GABA-ergic afferents from SNrpr to PPT contribute to REM sleep generation. The SNrpr is a part of basal ganglia and has reciprocal connections with PPT (Mena-Segovia et al 2004, Winn 2008). Both basal ganglia and PPT are therapeutic targets for the Parkinson's disease (Arnulf et al., 2008). Besides the motor abnormalities, Parkinson's patients also show abnormal sleep architecture and have a high incidence

Acknowledgments

The financial supports from Council of Scientific and Industrial Research and Department of Science and Technology to BNM and fellowship to DP from Council of Scientific and Industrial Research are duly acknowledged.

References (53)

  • D. Pal et al.

    GABA in pedunculo pontine tegmentum regulates spontaneous rapid eye movement sleep by acting on GABAA receptors in freely moving rats

    Neurosci Lett

    (2004)
  • D. Pal et al.

    Role of noradrenergic and GABA-ergic inputs in pedunculopontine tegmentum for regulation of rapid eye movement sleep in rats

    Neuropharmacology

    (2006)
  • M.S. Pollock et al.

    Rapid eye movement sleep induction by microinjection of the GABA-A antagonist bicuculline into the dorsal subcoeruleus area of the rat

    Brain Res

    (2003)
  • L.D. Sanford et al.

    Effects of tetrodotoxin (TTX) inactivation of the central nucleus of the amygdala (CNA) on dark period sleep and activity

    Brain Res

    (2006)
  • M.N. Shouse et al.

    Pontine regulation of REM sleep components in cats: integrity of the pedunculopontine tegmentum (PPT) is important for phasic events but unnecessary for atonia during REM sleep

    Brain Res

    (1992)
  • S. Singh et al.

    Mild electrical stimulation of pontine tegmentum around locus coeruleus reduces rapid eye movement sleep in rats

    Neurosci Res

    (1996)
  • K. Takakusaki et al.

    Evidence for a role of basal ganglia in the regulation of rapid eye movement sleep by electrical and chemical stimulation for the pedunculopontine tegmental nucleus and the substantia nigra pars reticulata in decerebrate cats

    Neuroscience

    (2004)
  • M. Thakkar et al.

    Chronic low-amplitude electrical stimulation of the laterodorsal tegmental nucleus of freely moving cats increases REM sleep

    Brain Res

    (1996)
  • S. Thankachan et al.

    Role of wake inducing brain stem area on rapid eye movement sleep regulation in freely moving cats

    Brain Res Bull

    (2001)
  • P. Torterolo et al.

    GABA-ergic mechanisms in the pedunculopontine tegmental nucleus of the cat promote active (REM) sleep

    Brain Res

    (2002)
  • P. Torterolo et al.

    GABAergic neurons of the laterodorsal and pedunculopontine tegmental nuclei of the cat express c-Fos during carbachol-induced active sleep

    Brain Res

    (2001)
  • R.P. Vertes

    Selective firing of rat pontine gigantocellular neurons during movement and REM sleep

    Brain Res

    (1977)
  • H.H. Webster et al.

    Neurotoxic lesions of the dorsolateral pontomesencephalic tegmentum-cholinergic cell area in the catII. Effects upon sleep-waking states

    Brain Res

    (1988)
  • P. Winn

    Experimental studies of pedunculopontine functions: are they motor, sensory or integrative?

    Parkinsonism Relat Disorders

    (2008)
  • I. Arnulf et al.

    Abnormal sleep and sleepiness in Parkinson's disease

    Curr Opin Neurol

    (2008)
  • L.M. Capece et al.

    New directions for the study of cholinergic REM sleep generation: specifying pre- and postsynaptic mechanisms

  • Cited by (31)

    • Dopaminergic- and cholinergic-inputs from substantia nigra and pedunculo-pontine tegmentum, respectively, converge in amygdala to modulate rapid eye movement sleep in rats

      2021, Neuropharmacology
      Citation Excerpt :

      This SN-Aymg pathway may work synergistically with the PPT-Amyg pathway or they may be independent and involved with expression of quality and quantity of hallucinations and dreams. We have shown how SN GABA-ergic neurons are responsible for the initiation of REMS only if wake input was withdrawn (Kumar et al., 2012; Mallick et al., 2012; Pal and Mallick, 2009). In those reports, we had proposed that dysfunctions of such REMS regulatory neuronal circuitry would cause appearance of REMS-like state (hallucinations or day-dreaming) during waking.

    • Interplay of dopamine and GABA in substantia nigra for the regulation of rapid eye movement sleep in rats

      2019, Behavioural Brain Research
      Citation Excerpt :

      A pair of flexible, stainless steel insulated wire (except at the tip) was implanted bilaterally in the dorsal neck muscles for recording EMG, while another pair of wires was connected to the eye muscles for recording EOG. 24 G stainless steel sterilized guide cannulae with obturators, designed and fabricated in the lab, were implanted bilaterally targeting SN (AP = -5.3 mm from bregma; ML = ±2 mm; DV = -7.8 mm) as described earlier [12,16]. The cannulae were stereotaxically introduced into the brain such that their tips reached 2 mm above the target areas.

    View all citing articles on Scopus
    1

    Present address: Department of Anesthesiology, University of Michigan, 1150 West Medical Center Drive, 7433 Medical Sciences Building 1, Ann Arbor, MI 48109-0615, USA. Tel: +1-734-615-7093; fax: +1-734-764-9332. E-mail address: [email protected].

    View full text