Elsevier

Brain Research

Volume 1298, 28 October 2009, Pages 24-36
Brain Research

Research Report
Identification of calcium sensing receptor (CaSR) mRNA-expressing cells in normal and injured rat brain

https://doi.org/10.1016/j.brainres.2009.08.074Get rights and content

Abstract

Calcium sensing receptor (CaSR), isolated for the first time from bovine and human parathyroid, is a G-protein-coupled receptors that has been involved in diverse physiological functions. At present a complete in vivo work on the identification of CaSR mRNA-expressing cells in the adult brain lacks and this investigation was undertaken in order to acquire more information on cell type expressing CaSR mRNA in the rat brain and to analyse for the first time its expression in different experimental models of brain injury. The expression of CaSR mRNAs was found mainly in scattered cells throughout almost all the brain regions. A double labeling analysis showed a colocalization of CaSR mRNA expression in neurons and oligodendrocytes, whereas it was not found expressed both in the microglia and in astrocytes. One week after kainate-induced seizure CaSR was found in the injured CA3 region of the hippocampus and very interestingly it was found up-regulated in the neurons of CA1–CA2 and dentate gyrus. Similarly, 1 week following ibotenic acid injection in the hippocampus, CaSR mRNA expression was increased in oligodendrocytes both in the lesioned area and in the contralateral CA1–CA3 pyramidal cell layers and dentate gyrus. One week after needle-induced mechanical lesion an increase of labeled cells expressing CaSR mRNA was observed along the needle track. In conclusion, the present results contribute to extend available data on cell type-expressing CaSR in normal and injured brain and could spur to understand the role of CaSR in repairing processes of brain injury.

Introduction

Calcium sensing receptor (CaSR) has been isolated for the first time from bovine and human parathyroid glands (Brown, 1991, Garrett et al., 1995), and later from rat brain (Ruat et al., 1995). The CaSR is predicted to be glycosylated proteins, with a large extracellular domain and the seven membrane spanning region characteristic of other G-protein-coupled receptors (Brown, 1991, Garrett et al., 1995, Riccardi et al., 1995), and it has been involved in diverse physiological functions (Chattopadhyay and Brown, 2000). Localization of transcripts for CaSR in the adult rat brain has been reported by Rogers KV and coworkers (1997), and more recently by Ferry et al. (2000), which performed an analysis of CaSR mRNA expression in the adult brain and its localization in neurons and oligodendrocytes. CaSR has been also found express both in astrocytes and microglia but these results have been achieved using primary cultures of human and rat brain respectively (Chattopadhyay et al., 1999, Chattopadhyay et al., 2000). Therefore, at present, a complete in vivo work on the identification of CaSR mRNA-expressing cells lacks and this study was undertaken in order to acquire more information on cell type expressing CaSR mRNA in the rat brain and to analyse for the first time the CaSR mRNA expression in different experimental models of brain injury: (a) bilateral lesion of hippocampal CA3 regions by kainate-induced seizure; (b) unilateral hippocampal lesion by a stereotaxic local injection of ibotenic acid; (c) mechanical lesion produced by a needle (30 G) stereotaxically introduced through the rostral cerebral cortex.

Section snippets

Expression of CaSR mRNA

A detailed analysis of CaSR expression in the normal rat brain was performed using in situ hybridization. Cells expressing CaSR mRNA were scattered throughout almost all the brain areas with regional differences in labeled cells density. Brain regions and nuclei that express CaSR mRNAs are listed in Table 1, that report the relative density of CaSR-expressing cells ranked on a scale from one to four, with “+” representing widely scattered cells (5-20%) and “++++” representing the highest cell

Discussion

Results regarding the brain distribution of CaSR transcripts are in agreement with data of previous works (Ferry et al., 2000, Rogers et al., 1997) confirming an expression of CaSR in all brain regions, with a particularly high abundance in subfornical organ, olfactory bulb and hypothalamus. However, we observed different intensity of signal in some brain regions or nuclei (e.g. hippocampal layers, hypothalamus nuclei) in comparison to previously reported data (Rogers et al. 1997). Such minor

Experimental procedures

Wistar adult male rats (250 g b.w.) from local stock have been used for the present study. The rats were kept under controlled temperature and standardized lighting and free access to food and water. Procedures involving animals and their care were conducted in conformity with the institutional guidelines that are in compliance with national and international laws and policies. All efforts were made to minimize the number of animals used and their suffering and all experiments were approved by

Acknowledgments

This work was funded by a grant from Italian M.I.U.R. (Progetti di Ricerca di Interesse Nazionale-PRIN, #9805089988_005), and from the University of Palermo and University of Catania (Finanziamenti Ricerca Scientifica di Ateneo).

References (27)

  • VerkhratskyA. et al.

    Calcium signalling in glial cells

    Trends Neurosci.

    (1996)
  • BelluardoN. et al.

    Induction of astroglial gene expression by experimental seizures in the rat: spatio-temporal patterns of the early stages

    Glia

    (1996)
  • BrownE.M.

    Extracellular Ca2+ sensing, regulation of parathyroid cell function, and role of Ca2+ and other ions as extracellular (first) messengers

    Physiol. Rev.

    (1991)
  • Cited by (19)

    • Enhanced expression of the calcium-sensing receptor in reactive astrocytes following ischemic injury in vivo and in vitro

      2016, Journal of the Neurological Sciences
      Citation Excerpt :

      In addition, our data revealed that activated microglia within the vulnerable region of the post-ischemic hippocampus were devoid of any specific labeling for CaSR, despite there being evident microglial reactivity in this area. These results contrast with a previous finding of microglial expression in cultured rat microglia [29], but agree well with findings showing an absence of CaSR in microglia/macrophages [11,20]. Astrocytic CaSR expression was evident on days 3–7 after reperfusion and increased progressively until day 28, which was the last time point examined in the present study.

    • Differential expression of the calcium-sensing receptor in the ischemic and border zones after transient focal cerebral ischemia in rats

      2015, Journal of Chemical Neuroanatomy
      Citation Excerpt :

      It is unclear why CaSR expression is induced in a subset of neurons in the border zone, and thus, characterization of these neurons using neurotransmitters or calcium-binding proteins is needed to further elucidate the functional significance of neuronal CaSR expression. However, in contrast to our findings, Mudo et al. (2009) reported the expression of CaSR mRNA in neurons and oligodendrocytes (but not in astrocytes and microglia), in normal animals and in those with kainate-induced seizures. In addition, Kim et al. (2011) demonstrated the induction of CaSR in hippocampal neurons, but not in astrocytes and microglia/macrophages, after global forebrain ischemia.

    • Roles of the calcium sensing receptor in the central nervous system

      2013, Best Practice and Research: Clinical Endocrinology and Metabolism
      Citation Excerpt :

      On the other hand, the developmental expression profile of CaSR in the hippocampus revealed time-dependent changes in expression in the cell bodies of the pyramidal cell layer.11 Detailed mapping of CaSR transcripts showed expression at different levels in several regions of the developing and adult brain in both the grey and white matter (Refs. 13–15 and Fig. 1). In the grey matter, many areas displayed isolated, widely scattered CaSR-expressing cells.

    View all citing articles on Scopus
    View full text