Immunohistochemical localisation of cholinergic muscarinic receptor subtype 1 (M1r) in the guinea pig and human enteric nervous system

Noradrenaline (NA) acting via ␤-adrenergic receptors (␤ARs) plays an important role in the modulation of memory in the hippocampus. ␤ARs have been shown to be expressed in principal cells, but their distribution across different interneuron classes is unknown. We have used specific interneuron markers including calcium binding proteins (parvalbumin, calbindin, and calretinin) and neuropeptides (somatostatin, neuropeptide Y, and cholecystokinin) together with either ␤1AR or ␤2AR to determine the distribution of these receptors in all major subfields of the hippocampus. We found that ␤1AR-expressing interneurons were more prevalent in the CA3 and CA1 regions of the hippocampus than in the dentate gyrus, where they were relatively sparse. ␤2AR-expressing interneurons were more uniformly distributed between all three regions of the hippocampus. A high proportion of neuropeptide Y-containing interneurons in the dentate gyrus co-expressed ␤2AR. ␤1AR labeling was common in interneurons expressing somatostatin and parvalbumin in the CA3 and CA1 regions, particularly in the stratum oriens of these regions. ␤2AR labeling was more likely to be found than ␤1AR labeling in cholecystokinin-expressing interneurons. In contrast, calretinin-containing interneurons were virtually devoid of ␤1AR or ␤2AR labeling. These regional and interneuron type-specific differences suggest functionally distinct roles for NA in modulating hippocampal activity via activation of ␤ARs.

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“…Preadsorption of the antibody with its immunizing peptide abolished all immunostaining in guinea pig ileum (Harrington et al, 2007).…”

Section: Antibody Characterizationmentioning

confidence: 97%

β‐adrenergic receptors are differentially expressed in distinct interneuron subtypes in the rat hippocampus

Cox

Racca

LeBeau

2008

J of Comparative Neurology

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“…M1rs have a high affinity for pirenzepine, whereas M2rs have a low affinity. M1rs are located post-synaptically within the guinea-pig myenteric plexus (North et al 1985;Christofi et al 1991;Harrington et al 2007), with the inhibitory pre-synaptic muscarinic receptor subtype suggested to be the M2r. In the submucosal plexus of the guinea-pig ileum, presynaptic M2rs have been described as facilitating the inhibition of the release of ACh and noradrenaline from nerve terminals (North et al 1985).…”

Section: Discussionmentioning

confidence: 99%

“…In the guinea-pig ileum, nNOS-IR neurons have been shown to have post-junctional M1rs that stimulate the synthesis and release of NO upon ACh binding (Iverson et al 1997;Olgart and Iversen 1999;Harrington et al 2007). They also bear receptors for SP, in particular neurokinin 1 receptors Harrington et al 2005).…”

Section: Discussionmentioning

confidence: 99%

“…It is known that pirenzipine acts on both M1rs and M2rs, with M1rs having a higher affinity than M2rs. M1rs are located on neurons within the myenteric ganglia (Harrington et al 2007). Thus, M2rs may mediate the effects of ACh-mediated muscle reflexes not only via its location on the smooth muscle but also via M2rs on nerve fibres regulating the release of transmitter onto muscle and within the myenteric ganglia.…”

Section: Introductionmentioning

confidence: 99%

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Immunohistochemical localisation of pre-synaptic muscarinic receptor subtype-2 (M2r) in the enteric nervous system of guinea-pig ileum

2008

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The cholinergic muscarinic 2 receptor (M2r) is known to be present on smooth muscle cells in the intestine. Pharmacological studies also suggest that M2rs regulate transmitter release from nerves in the enteric nervous system. This study localised M2rs in the guinea-pig ileum using different antibodies and fluorescence immunohistochemistry. Double labelling with antibodies against neurochemical markers was used to identify the type of nerves bearing M2r. Guinea-pig ileum were fixed, prepared for sections and wholemounts and incubated with antisera against the M2r sequence. Tissue was double labelled with antibodies against neuronal nitric oxide synthase (nNOS), common choline acetyltransferase (cChAT), substance P (SP), synaptophysin and vesicular acetylcholine transporter (VAChT). Immunofluorescence was viewed using confocal microscopy. Abundant M2r-immunoreactivity (IR) was present on the surface of circular and longitudinal smooth muscle cells. M2r-IR was present in many but not all nerve fibres in the circular muscle and ganglia. M2r-IR was present in VAChT-IR and cChAT-IR cholinergic nerve fibres and SP-IR nerve fibres in the myenteric ganglia and submucosal ganglia. M2r-IR was present on a few nNOS-IR nerve fibres and around nNOS-IR neurons in the myenteric ganglia. In the circular muscle and deep muscular plexus, M2r-IR was present in many VAChT-IR and SP-IR nerve fibres and in few nNOS-IR nerves. M2rs are not only present on muscle cells in the intestine, but also on nerve fibres. M2rs may mediate cholinergic reflexes via their location on muscle and also via neural transmission. The pre-synaptic location supports pharmacological studies suggesting M2rs mediate neurotransmitter release from nerve fibres. The presence of M2rs on VAChT-IR, SP-IR and nNOS-IR-containing nerve fibres suggests M2rs may regulate ACh, SP and nitric oxide release.

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“…Tissue was mounted on gelatin‐subbed slides and coverslipped with SlowFade medium (Thermo Fisher Scientific, Waltham, MA, USA). All antibodies had previously been characterised and validated by preadsorption experiments (Table ) . However, only the AgRP and kisspeptin antibodies had previously been validated in nonhuman primate tissue.…”

Section: Methodsmentioning

confidence: 99%

Arcuate nucleus neuropeptide coexpression and connections to gonadotrophin‐releasing hormone neurones in the female rhesus macaque

True

Takahashi

Kirigiti

et al. 2017

J Neuroendocrinology

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The underlying hypothalamic neurocircuitry by which metabolism and feeding regulates reproductive function has been well-studied in the rodent; however, recent data demonstrated significant neuroanatomical differences in the human brain. The current study had three objectives, centered on arcuate nucleus neuropeptides regulating feeding and reproduction: 1) characterize coexpression patterns in the female nonhuman primate, 2) establish whether these neuronal populations make potential contacts with GnRH neurons and 3) determine whether these contacts differ between the low and high GnRH-releasing states of pre-puberty and adulthood, respectively. Female nonhuman primates have several coexpression patterns of hypothalamic neuropeptides that differ from those reported in rodents. Cocaine- and amphetamine-regulated transcript (CART) is not coexpressed with proopiomelanocortin (POMC) but instead with neuropeptide Y (NPY). CART is also expressed in a subpopulation of kisspeptin cells in the nonhuman primate, similar to observations in humans but diverging from findings in rodents. Very few GnRH-expressing neurons received close appositions from double-labeled kisspeptin/CART fibers; however, both single-labeled kisspeptin and CART fibers were in frequent apposition with GnRH neurons with no differences between prepubertal and adult animals. NPY/AgRP coexpressing fibers contacted significantly more GnRH neurons in prepubertal animals than adults, consistent with increased NPY and AgRP mRNA observed in prepubertal animals. The current findings detail significant differences in arcuate nucleus neuropeptide coexpression in the monkey compared to the rodent and are consistent with the hypothesis that arcuate nucleus NPY/AgRP neurons play an inhibitory role in controlling GnRH neuronal regulation in the prepubertal primate.

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Immunohistochemical localisation of cholinergic muscarinic receptor subtype 1 (M1r) in the guinea pig and human enteric nervous system

Cited by 21 publications

References 45 publications

β‐adrenergic receptors are differentially expressed in distinct interneuron subtypes in the rat hippocampus

β‐adrenergic receptors are differentially expressed in distinct interneuron subtypes in the rat hippocampus

Immunohistochemical localisation of pre-synaptic muscarinic receptor subtype-2 (M2r) in the enteric nervous system of guinea-pig ileum

Arcuate nucleus neuropeptide coexpression and connections to gonadotrophin‐releasing hormone neurones in the female rhesus macaque

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