Interactive reportComparative distribution of NK1, NK2, and NK3 receptors in the rat brainstem auditory nuclei
Introduction
Tachykinins are a family of neuropeptides that include substance P (SP), neurokinin A (NKA) and neurokinin B (NKB). These structurally related neuropeptides share a common carboxyl-terminal pentapeptide sequence [3]. Tachykinins have been shown to have a wide distribution in both the central and the peripheral nervous systems (see Ref. [15] for review). To exert their effect, SP, NKA and NKB interact with three different G-protein coupled receptors (neurokinin receptors) NK1-R, NK2-R and NK3-R. These neurokinin receptors bind tachykinin neuropeptides with different affinities (NK1-R: SP>NKA>NKB; NK2-R: NKA>NKB>SP; NK3-R: NKB>NKA>SP) [4], [13], [17].
The distribution of SP has been widely studied in the central auditory system of different species [1], [6], [8], [10], [11], [12], [16], [19], [20], [21], [26], [27]. These studies showed a strong expression of SP in fibers innervating most auditory nuclei. However, the origin of these SP fibers remains unknown, although some SP positive cell bodies have been observed in the ventral cochlear nucleus, the lateral lemniscus nucleus and in the inferior colliculus using immunohistochemical techniques and in situ hybridization [26], [27]. In addition, recent electrophysiological studies on brain slices in vitro have shown that SP depolarizes and increases the firing rates of neurons of the superior olive complex nuclei, suggesting the presence of functional NK1-R receptors and that these auditory structures receive excitatory input from a substance P-utilizing neural pathway [22], [23], [24].
Although an immunohistochemical mapping of the neurokinin receptor subunits has been reported in the central nervous system using autoradiography and immunohistochemistry [7], [9], [28], there is no information regarding their distribution in the central auditory system. The aim of the present study was to characterize the expression of neurokinin receptors in the central auditory system using immunohistochemical techniques. For this purpose, three polyclonal antibodies each recognizing specifically one member of the tachykinin receptors NK1-R, NK2-R and NK3-R were used [2].
Section snippets
Materials and methods
Two to 3-month-old (n=10) Sprague–Dawley rats were used in this study. Rats were deeply anaesthetized (sodium pentobarbital; 80 mg/kg), and perfused intra-cardially with a fresh solution of 4% paraformaldehyde and 0.2% glutaraldehyde in 0.1 M phosphate buffer solution (PBS). Brains were removed and post-fixed overnight at 4 °C in the same solution. Vibratome sections (30–70 μm) were obtained and incubated in 1% sodium borohydrate to remove excess fixative. Sections were incubated in 1% H2O2 to
NK1-R immunolabelling
NK1-R immunoreactivity was observed in the majority of neurons of both ventral (VCN) and dorsal (DCN) cochlear nucleus (CN) subdivisions (Fig. 1A and C). At high magnification NK1-R labeling was observed in neuronal cell bodies and proximal dendrites (Fig. 1B and D). Some of the NK1-R staining was observed as dots on the surface of the neuronal cell membranes. In the DCN, some neurons revealed the NK1-R staining in their principal dendrites. No immunoreactivity was observed in fibers all over
Discussion
The present study describes for the first time the cellular localization of the three tachykinin receptors NK1-R, NK2-R and NK3-R in the rat central auditory system. The immunoreactivity reveals a wide and similar distribution of the three receptors in the central auditory nuclei. The immunoreactivity was restricted to neurons and more specifically to the somatic compartment suggesting the presence of tachykinin terminals around the neuronal perikarya. Although the immunoreactivity was
Acknowledgements
We thank Dr N.W. Bunnett (Department of Surgery, School of Medicine, University of California, San Francisco, CA, USA) for providing us with the antibodies against the NK receptors. We would also like to thank the Conseil Régional d’Aquitaine and the Fondation pour la Recherche Médicale for grant support.
References (28)
- et al.
Regional distribution of substance P-like immunoreactivity in the lower brainstem of the rat
Brain Res.
(1982) - et al.
Tachykinin receptor subtypes: classification and membrane signaling mechanisms
Neurochem. Int.
(1991) - et al.
Detailed distribution of neurokinin 3 receptors in the rat, guinea pig and gerbil brain: a comparative autoradiographic study
Neuropharmacology
(2001) - et al.
Distribution of the substance P receptor (NK-1 receptor) in the central nervous system
Mol. Brain Res.
(1993) - et al.
Neurokinin-3 receptor distribution in rat and human brain: an immunohistochemical study
Neuroscience
(1999) - et al.
Morphological relationships of peptidergic and noradrenergic nerve terminals to olivocochlear neurones in the rat
Hear. Res.
(2000) - et al.
Distribution of substance P-like immunoreactive structures in the brainstem of the adult human brain: an immunocytochemical study
Brain Res.
(1987) - et al.
Ontogeny of substance P-containing neuron system of the rat: immunohistochemical analysis. II. Lower brain stem
Neuroscience
(1982) - et al.
Experimental and immunohistochemical studies concerning the major origins of substance-P containing fibers in the lateral lemniscus and lateral parabrachial area of the rat, including fiber pathways
Neuroscience
(1983) - et al.
Regional distribution of serotonin and substance P co-existing in nerve fibers and terminals in the brainstem of the rat
Neuroscience
(1993)
Substance P-sensitive neurones in the rat auditory brainstem: possible relationship to medial olivocochlear neurones
Hear. Res.
Effects of bioamines and peptides on neurones in the ventral nucleus of trapezoid body and rostral periolivary regions of the rat superior olivary complex: an in vitro investigation
Hear. Res.
Neurotransmitter and neuromodulator systems of the rat inferior colliculus and auditory brainstem studied by in situ hybridization
J. Chem. Neuroanat.
Characterization of antisera specific to NK1, NK2, and NK3 neurokinin receptors and their utilization to localize receptors in the rat gastrointestinal tract
J. Neurosci.
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