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Distribution and characterisation of Glucagon-like peptide-1 receptor expressing cells in the mouse brain.

Cork SC, Richards JE, Holt MK, Gribble FM, Reimann F, Trapp S - Mol Metab (2015)

Bottom Line: Large numbers of eYFP or tdRFP immunoreactive cells were found in the circumventricular organs, amygdala, hypothalamic nuclei and the ventrolateral medulla.However, tdRFP positive neurons were also found in areas without preproglucagon-neuronal projections like hippocampus and cortex.GLP-1R expression was confirmed in whole-cell recordings from BNST, hippocampus and PVN, where 100 nM GLP-1 elicited a reversible inward current or depolarisation.

View Article: PubMed Central - PubMed

Affiliation: Centre for Cardiovascular and Metabolic Neuroscience, Department of Neuroscience, Physiology & Pharmacology, University College London, London, WC1E 6BT, UK.

ABSTRACT

Objective: Although Glucagon-like peptide 1 is a key regulator of energy metabolism and food intake, the precise location of GLP-1 receptors and the physiological relevance of certain populations is debatable. This study investigated the novel GLP-1R-Cre mouse as a functional tool to address this question.

Methods: Mice expressing Cre-recombinase under the Glp1r promoter were crossed with either a ROSA26 eYFP or tdRFP reporter strain to identify GLP-1R expressing cells. Patch-clamp recordings were performed on tdRFP-positive neurons in acute coronal brain slices from adult mice and selective targeting of GLP-1R cells in vivo was achieved using viral gene delivery.

Results: Large numbers of eYFP or tdRFP immunoreactive cells were found in the circumventricular organs, amygdala, hypothalamic nuclei and the ventrolateral medulla. Smaller numbers were observed in the nucleus of the solitary tract and the thalamic paraventricular nucleus. However, tdRFP positive neurons were also found in areas without preproglucagon-neuronal projections like hippocampus and cortex. GLP-1R cells were not immunoreactive for GFAP or parvalbumin although some were catecholaminergic. GLP-1R expression was confirmed in whole-cell recordings from BNST, hippocampus and PVN, where 100 nM GLP-1 elicited a reversible inward current or depolarisation. Additionally, a unilateral stereotaxic injection of a cre-dependent AAV into the PVN demonstrated that tdRFP-positive cells express cre-recombinase facilitating virally-mediated eYFP expression.

Conclusions: This study is a comprehensive description and phenotypic analysis of GLP-1R expression in the mouse CNS. We demonstrate the power of combining the GLP-1R-CRE mouse with a virus to generate a selective molecular handle enabling future in vivo investigation as to their physiological importance.

No MeSH data available.


Related in: MedlinePlus

Dual immunofluorescence of GLP-1R-eYFP expressing neurons and tyrosine hydroxylase (TH) expressing neurons throughout the brain. A. Only few TH neurons in the NTS were found to co-localise with eYFP expressing neurons. Conversely, almost all TH positive neurons in the AP co-expressed GLP-1R. B. Higher magnification image of boxed region in A. C. Around half of all TH positive neurons in the RVLM co-expressed GLP-1R, however the majority of GLP-1R neurons were TH-negative. D. A few TH positive neurons in the DMH were found to have eYFP staining, however the majority did not. E. Only a few TH positive neurons in the VTA expressed GLP-1R. Indeed the VTA contained very few GLP-1R positive somata. F–I. Scale bars in A, C, D and E = 200 μm. B, F, H and I = 20 μm. G = 50 μm. Arrow heads in B, F–I represent dual labelled neurons. * = YFP positive, TH negative neurons.
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fig4: Dual immunofluorescence of GLP-1R-eYFP expressing neurons and tyrosine hydroxylase (TH) expressing neurons throughout the brain. A. Only few TH neurons in the NTS were found to co-localise with eYFP expressing neurons. Conversely, almost all TH positive neurons in the AP co-expressed GLP-1R. B. Higher magnification image of boxed region in A. C. Around half of all TH positive neurons in the RVLM co-expressed GLP-1R, however the majority of GLP-1R neurons were TH-negative. D. A few TH positive neurons in the DMH were found to have eYFP staining, however the majority did not. E. Only a few TH positive neurons in the VTA expressed GLP-1R. Indeed the VTA contained very few GLP-1R positive somata. F–I. Scale bars in A, C, D and E = 200 μm. B, F, H and I = 20 μm. G = 50 μm. Arrow heads in B, F–I represent dual labelled neurons. * = YFP positive, TH negative neurons.

Mentions: The mesolimbic system exhibited high densities of GLP-1R neurons in the BNST (Figure 3C), the amygdala (Figure 3D) and the lateral septum (LS; Figure 3E). Interestingly, only few somata were identified in the ventral tegmental area (VTA) (Figure 4E) and NAc (Figure 3B), although both areas have previously been investigated in relation to the effects of GLP-1R activation on food intake in rats.


Distribution and characterisation of Glucagon-like peptide-1 receptor expressing cells in the mouse brain.

Cork SC, Richards JE, Holt MK, Gribble FM, Reimann F, Trapp S - Mol Metab (2015)

Dual immunofluorescence of GLP-1R-eYFP expressing neurons and tyrosine hydroxylase (TH) expressing neurons throughout the brain. A. Only few TH neurons in the NTS were found to co-localise with eYFP expressing neurons. Conversely, almost all TH positive neurons in the AP co-expressed GLP-1R. B. Higher magnification image of boxed region in A. C. Around half of all TH positive neurons in the RVLM co-expressed GLP-1R, however the majority of GLP-1R neurons were TH-negative. D. A few TH positive neurons in the DMH were found to have eYFP staining, however the majority did not. E. Only a few TH positive neurons in the VTA expressed GLP-1R. Indeed the VTA contained very few GLP-1R positive somata. F–I. Scale bars in A, C, D and E = 200 μm. B, F, H and I = 20 μm. G = 50 μm. Arrow heads in B, F–I represent dual labelled neurons. * = YFP positive, TH negative neurons.
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fig4: Dual immunofluorescence of GLP-1R-eYFP expressing neurons and tyrosine hydroxylase (TH) expressing neurons throughout the brain. A. Only few TH neurons in the NTS were found to co-localise with eYFP expressing neurons. Conversely, almost all TH positive neurons in the AP co-expressed GLP-1R. B. Higher magnification image of boxed region in A. C. Around half of all TH positive neurons in the RVLM co-expressed GLP-1R, however the majority of GLP-1R neurons were TH-negative. D. A few TH positive neurons in the DMH were found to have eYFP staining, however the majority did not. E. Only a few TH positive neurons in the VTA expressed GLP-1R. Indeed the VTA contained very few GLP-1R positive somata. F–I. Scale bars in A, C, D and E = 200 μm. B, F, H and I = 20 μm. G = 50 μm. Arrow heads in B, F–I represent dual labelled neurons. * = YFP positive, TH negative neurons.
Mentions: The mesolimbic system exhibited high densities of GLP-1R neurons in the BNST (Figure 3C), the amygdala (Figure 3D) and the lateral septum (LS; Figure 3E). Interestingly, only few somata were identified in the ventral tegmental area (VTA) (Figure 4E) and NAc (Figure 3B), although both areas have previously been investigated in relation to the effects of GLP-1R activation on food intake in rats.

Bottom Line: Large numbers of eYFP or tdRFP immunoreactive cells were found in the circumventricular organs, amygdala, hypothalamic nuclei and the ventrolateral medulla.However, tdRFP positive neurons were also found in areas without preproglucagon-neuronal projections like hippocampus and cortex.GLP-1R expression was confirmed in whole-cell recordings from BNST, hippocampus and PVN, where 100 nM GLP-1 elicited a reversible inward current or depolarisation.

View Article: PubMed Central - PubMed

Affiliation: Centre for Cardiovascular and Metabolic Neuroscience, Department of Neuroscience, Physiology & Pharmacology, University College London, London, WC1E 6BT, UK.

ABSTRACT

Objective: Although Glucagon-like peptide 1 is a key regulator of energy metabolism and food intake, the precise location of GLP-1 receptors and the physiological relevance of certain populations is debatable. This study investigated the novel GLP-1R-Cre mouse as a functional tool to address this question.

Methods: Mice expressing Cre-recombinase under the Glp1r promoter were crossed with either a ROSA26 eYFP or tdRFP reporter strain to identify GLP-1R expressing cells. Patch-clamp recordings were performed on tdRFP-positive neurons in acute coronal brain slices from adult mice and selective targeting of GLP-1R cells in vivo was achieved using viral gene delivery.

Results: Large numbers of eYFP or tdRFP immunoreactive cells were found in the circumventricular organs, amygdala, hypothalamic nuclei and the ventrolateral medulla. Smaller numbers were observed in the nucleus of the solitary tract and the thalamic paraventricular nucleus. However, tdRFP positive neurons were also found in areas without preproglucagon-neuronal projections like hippocampus and cortex. GLP-1R cells were not immunoreactive for GFAP or parvalbumin although some were catecholaminergic. GLP-1R expression was confirmed in whole-cell recordings from BNST, hippocampus and PVN, where 100 nM GLP-1 elicited a reversible inward current or depolarisation. Additionally, a unilateral stereotaxic injection of a cre-dependent AAV into the PVN demonstrated that tdRFP-positive cells express cre-recombinase facilitating virally-mediated eYFP expression.

Conclusions: This study is a comprehensive description and phenotypic analysis of GLP-1R expression in the mouse CNS. We demonstrate the power of combining the GLP-1R-CRE mouse with a virus to generate a selective molecular handle enabling future in vivo investigation as to their physiological importance.

No MeSH data available.


Related in: MedlinePlus