Development of metabotropic glutamate receptors from trigeminal nuclei to barrel cortex in postnatal mouse

Abstract

Expression patterns of group I (mGluR1α and mGluR5) and group II (mGluR2/3) metabotropic glutamate receptor subtypes were examined immunocytochemically in the trigeminal system of mice during the first 3 weeks of postnatal development, when somatotopic whisker representations are sequentially established from brainstem through thalamus to cerebral cortex. Immunostaining for all three epitopes formed whisker‐related patterns in the trigeminal nuclei from postnatal day (P) 0, in the ventral posterior thalamic nucleus from P2, and in the posteromedial barrel subfield of somatosensory cortex (SI) from P4. The appearance of whisker‐related patterns was preceded by increased levels of immunostaining of the neuropil, which subsequently declined from the trigeminal nuclei upward. In SI, mGluR1α‐positive neurons were observed in all cortical layers from P2. mGluR5 was localized in neurons, glial cells, and neuropil from P2. mGluR2/3 immunostaining was distributed only in the neuropil at all ages. The three receptor subtypes showed moderate to high expression in deep layer V throughout development. Transient expression peaked in the hollows of layer IV barrels from P4 to P9, and then fell off as expression increased in supragranular layers from P14 to P21. The deep aspect of the cortical subplate (layer VIb) showed dense mGluR5 and less dense mGluR1α immunostaining throughout development. Up‐regulation of expression of group I and II mGluRs is correlated with the growth and refinement of connectivity and the establishment of somatotopic patterns in the three main relay stations of the trigeminal system. This finding suggests roles for mGluRs in the early processing of sensory information and in developmental plasticity. J. Comp. Neurol. 409:549–566, 1999. © 1999 Wiley‐Liss, Inc.

Neonatal Fluoxetine Exposure Affects the Neuronal Structure in the Somatosensory Cortex and Somatosensory-Related Behaviors in Adolescent Rats

“…Agonist and antagonist of 5-HT 2A R are now being used to test this possibility. Moreover, the involvement of other serotonin or glutamate receptors in the process of axonal and dendritic refinement still remains to be clarified (Muñoz et al 1999;Hannan et al 2001;Spires et al 2005).…”

Local group I mGluR antagonists reduce TMJ-evoked activity of trigeminal subnucleus caudalis neurons in female rats

“…First, from considerable evidence that group I mGluRs (mGluR1 and mGluR5) act at spinal levels to modulate nociception and pain-like behavior (Neugebauer, 2002;Varney and Gereau, 2002;Goudet et al, 2009) and secondly, from studies linking estrogen actions in the brain to membrane-bound mGluRs (Meitzen and Mermelstein, 2011). Group I mGluRs have primarily a pro-nociceptive function and are expressed in the superficial laminae of the spinal dorsal horn (Jia et al, 1999;Alvarez et al, 2000) and in the Vc/C 1-2 region (Munoz et al, 1999;Tang et al, 2001). Spontaneous nociceptive behavior induced by spinal administration of a mixed group I agonist was reduced by intrathecal injection of selective antibodies (Fundytus, et al, 1998) or antagonists for mGluR1 or mGluR5 .…”

“…Group I mGluRs also are closely linked to estrogen actions in the brain (Micevych and Mermelstein, 2008;Meitzen and Mermelstein, 2011). Group I mGluRs are abundantly distributed throughout the trigeminal brainstem sensory complex including within the superficial laminae at the Vc/C 1-2 region and spinal dorsal horn (Munoz et al, 1999;Jia et al, 1999;Alvarez et al, 2000;Tang et al, 2001). Physiological studies in animals (Cairns et al, 2001b;Bereiter and Benetti, 2006) and psychophysical studies in humans (Cairns et al, 2001a) suggest that glutamatergic pathways play a key role in TMJ nociception.…”

Metabotropic glutamate receptor 5 shows different patterns of localization within the parallel visual pathways in macaque and squirrel monkeys

“…57 mGluR5 also has been observed within astrocytes by several groups in multiple areas of the nervous system, including the cerebral cortex. 27,58–60 …”

“…These findings are in general agreement with what others have found in different cortical regions in other species. Most investigators have reported that mGluR5 is localized perisynaptically within cortical dendrites, 58,60–65 although no previous EM study specifically focused on the visual cortex in primates. Some, but not all, investigators also have reported the presence of mGluR5 within axon terminals.…”