Neurotensin regulates intracellular calcium in ventral tegmental area astrocytes: evidence for the involvement of multiple receptors
Section snippets
Cell culture
Primary cultures of rat VTA were prepared from neonatal animals (postnatal days 1–3). Two small blocks of tissue containing the left and right portions of the VTA were dissected out using a custom tissue micropunch from a coronal slice with a thickness of approximately 1.5 mm and localized rostrocaudally at the level of the midbrain flexure. The tissue was incubated in papaı̈n for 30 min and dissociated according to a protocol modified from Cardozo.12 Modifications to the protocol included the
Calcium-mobilizing action of neurotensin(8–13) on ventral tegmental area astrocytes
Experiments were performed on primary cultures of rat VTA. These preparations contained both neurons and astrocytes. Dopaminergic neurons comprised approximately 50% of the neuronal population, other neurons being mostly GABAergic. A glial cell monolayer covered most of the coverslip surface. These cells were exclusively astrocytes as suggested by their immunoreactivity to glial fibrillary acidic protein (not shown).
Intracellular Ca2+ concentration in astrocytes was monitored by fluorescence
Identity of neurotensin receptors on astrocytes
Although previous reports have already suggested that astrocytes can express NT receptors,34., 51., 52. the identity of the receptor(s) and the functional consequences of the activation of such receptors were unclear. The present work clarifies these issues by providing a detailed characterization of NT-evoked Ca2+ signalling in cultured VTA astrocytes. In line with the report of Hösli et al.,34 the present results are compatible with the idea that cultured VTA astrocytes express NT1 receptors.
Conclusions
This work provides clear evidence for the existence of functional NT receptors in astrocytes. These receptors cause a mobilization of intracellular Ca2+ and display pharmacological properties that are difficult to explain with the existence of a single type of NT receptor in astrocytes. Because the present work was performed in cultured cells, it remains unclear whether the reported observations have direct relevance for an understanding of the actions of NT in the intact brain. The first
Acknowledgements
This work was supported in part by the Medical Research Council of Canada, the EJLB Foundation, the Fonds de la Recherche en Santé du Québec and the Fonds pour les Chercheurs et l'Aide à la Recherche du Québec. Helpful comments on this manuscript were provided by Drs Philip Haydon, Pierre-Paul Rompré and Patrice Congar, as well as by François Michel. The assistance of Isabel Jutras and Marie-Josée Bourque in the preparation of cell cultures is acknowledged. The NT receptor antagonists SR48692
References (74)
- et al.
Tripartite synapses: glia, the unacknowledged partner
Trends Neurosci.
(1999) - et al.
Characterization of binding sites of a new neurotensin receptor antagonist, [3H]SR 142948A, in the rat brain
Eur. J. Pharmac.
(1998) - et al.
SR 48692 inhibits neurotensin-induced [3H]dopamine release in rat striatal slices and mesencephalic cultures
Eur. J. Pharmac.
(1994) - et al.
Substance P, neurotensin and enkephalin injections into the ventral tegmental area: comparative study on dopamine turnover in several forebrain structures
Brain Res.
(1989) Midbrain dopaminergic neurons from postnatal rat in long-term primary cultures
Neuroscience
(1993)- et al.
The isolation of a new hypotensive peptide, neurotensin, from bovine hypothalami
J. biol. Chem.
(1973) - et al.
Implication of various forms of neurotensin receptors in the mechanism of internalization of neurotensin in cerebral neurons
J. biol. Chem.
(1993) - et al.
Molecular cloning of a levocabastine-sensitive neurotensin binding site
Fedn Eur. biochem. Socs Lett.
(1996) - et al.
Characterization of neurotensin binding sites on rat mesencephalic cells in primary culture
Brain Res. devl Brain Res.
(1991) - et al.
Molecular mechanisms of G protein-coupled receptor desensitization and resensitization
Life Sci.
(1998)
A new generation of Ca2+ indicators with greatly improved fluorescence properties
J. biol. Chem.
Involvement of potentially distinct neurotensin receptors in neurotensin-induced stimulation of striatal [3H]dopamine release evoked by KCl versus electrical depolarization
Neuropharmacology
Rapid desensitization of agonist-induced calcium mobilization in transfected PC12 cells expressing the rat neurotensin receptor
Biochem. biophys. Res. Commun.
Mechanisms of regulation of neurotensin receptors
Pharmac. Ther.
Phospholipase C activation by neurotensin and neuromedin N in Chinese hamster ovary cells expressing the rat neurotensin receptor
Brain Res. molec. Brain Res.
Dopamine-dependent contralateral circling induced by neurotensin applied unilaterally to the ventral tegmental area in rats
Brain Res. Bull.
Autoradiographic and electrophysiological evidence for the existence of neurotensin receptors on cultured astrocytes
Neuroscience
Relationships between structure and duration of neurotensin's central action: emergence of long acting analogs
Neuropeptides
Regulation of neurotensin-containing neurons in the rat striatum. Effects of unilateral striatal lesions with quinolinic acid and ibotenic acid on neurotensin content and its binding site density
Brain Res.
The 100-kDa neurotensin receptor is gp95/sortilin, a non-G-protein-coupled receptor
J. biol. Chem.
Distribution of neurotensin binding sites in rat brain: a light microscopic radioautographic study using monoiodo [125I]Tyr3-neurotensin
Neuroscience
Electrophysiological evidence for putative subtypes of neurotensin receptors in guinea-pig mesencephalic dopaminergic neurons
Neuroscience
Centrally administered [d-Trp11]neurotensin, as well as neurotensin protected from inactivation by thiorphan, modifies locomotion in rats in a biphasic manner
Peptides
Pharmacological, molecular and functional characterization of glial neurotensin receptors
Neuroscience
Neurotensin depolarizes substantia nigra dopamine neurones
Brain Res.
Interactions between neurotensin and dopamine in the brain: an overview
Peptides
Autoradiographic distribution of [3H]neurotensin receptors in rat brain: visualization by tritium-sensitive film
Peptides
Modulation of synaptic efficacy and synaptic depression by glial cells at the frog neuromuscular junction
Neuron
Facilitation of brain stimulation reward by mesencephalic injections of neurotensin(1–13)
Eur. J. Pharmac.
Neurotensin and neuromedin N elevate the cytosolic calcium concentration via transiently appearing neurotensin binding sites in cultured rat cortex cells
Brain Res. devl Brain Res.
Human umbilical vein endothelial cells express high affinity neurotensin receptors coupled to intracellular calcium release
J. biol. Chem.
Electrophysiological effects of neurotensin on dopaminergic neurones of the ventral tegmental area of the rat in vitro
Neuropharmacology
Effects of microinjections of cholecystokinin and neurotensin into lateral hypothalamus and ventral mesencephalon on intracranial self-stimulation
Pharmac. Biochem. Behav.
Differential effects of neurotensin on dopamine release in the caudal and rostral nucleus accumbens: a combined in vivo electrochemical and electrophysiological study
Neuroscience
SR 48692, a non-peptide neurotensin receptor antagonist, differentially affects neurotensin-induced behaviour and changes in dopaminergic transmission
Neuroscience
Neurochemical and behavioural effects of neurotensin vs [d-Tyr11]neurotensin on mesolimbic dopaminergic function
Neuropeptides
Structure and functional expression of the cloned rat neurotensin receptor
Neuron
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Neurotensin reduces glutamatergic transmission in the dorsolateral striatum via retrograde endocannabinoid signaling
2008, NeuropharmacologyCitation Excerpt :Second, it is possible that NT acts on somatodendritic NTS1 receptors on the MSNs themselves. Because this receptor is Gq-coupled, and known to activate the phospholipase C pathway (Hermans et al., 1992; Trudeau, 2000; Belmeguenai et al., 2003), it could directly lead to endocannbinoid production and release (Piomelli, 2003). Thus NTS1 could be similar to group I mGluRs, which are also Gq-coupled, the activation of which is known to result in endocannabinoid production and release.
Mesolimbic dopamine and cortico-accumbens glutamate afferents as major targets for the regulation of the ventral striato-pallidal GABA pathways by neurotensin peptides
2007, Brain Research ReviewsCitation Excerpt :In view of the above it may be suggested that local application of NT in the nucleus accumbens regulates prejunctional dopaminergic transmission mainly via indirect mechanisms involving other neuronal systems (see next paragraph) rather than through a direct activation of the few NTS1 receptor located on accumbal dopaminergic terminals. As a consequence of the findings indicating that the location of NT receptors are not only expressed on neurons but also on astrocytes (Nouel et al., 1999; Trudeau, 2000) it could be suggested that under specific conditions of local treatments such as perfusion of NT via a microdialysis probe, the NT induced changes on extracellular dialysate levels of glutamate could be considered not only as a result of the activation of the neuron (synaptic release) but also of astrocytes (volume transmission). The term volume transmission describes the transfer of a signal in the extracellular space including the diffusion of chemical signals like transmitters and modulators in the extracellular fluid.