Ghrelin Receptor (GHSR) Neurons

Ghrelin Receptor (GHSR) Neurons

Introduction

<table class="infobox infobox-cell">
<tr>
<th class="infobox-header" colspan="2">Ghrelin Receptor (GHSR) Neurons</th>
</tr>
<tr>
<td class="label">Taxonomy</td>
<td>ID</td>
</tr>
<tr>
<td class="label">Cell Ontology (CL)</td>
<td>[CL:0000197](https://www.ebi.ac.uk/ols4/ontologies/cl/classes/http%253A%252F%252Fpurl.obolibrary.org%252Fobo%252FCL_0000197)</td>
</tr>
</table>

Ghrelin Receptor (Ghsr) Neurons is an important cell type in the neurobiology of neurodegenerative diseases. This page provides detailed information about its structure, function, and role in disease processes.

Overview

Neurons expressing ghrelin receptor (GHSR), also known as the growth hormone secretagogue receptor (GHS-R). GHSR is a G protein-coupled receptor that binds ghrelin, the "hunger hormone" produced primarily in the stomach. GHSR neurons are widely distributed in the brain and play critical roles in growth hormone secretion, appetite regulation, energy homeostasis, memory formation, and neuroprotection. GHSR represents a unique target for understanding the link between metabolic state and cognitive function, with important implications for neurodegenerative diseases. [@ghrelin2020]

<!-- multi-taxonomy-enrichment -->

Multi-Taxonomy Classification

Taxonomy Database Cross-References

External Database Links

Ghrelin Receptor (GHSR) Neurons

Introduction

<table class="infobox infobox-cell">
<tr>
<th class="infobox-header" colspan="2">Ghrelin Receptor (GHSR) Neurons</th>
</tr>
<tr>
<td class="label">Taxonomy</td>
<td>ID</td>
</tr>
<tr>
<td class="label">Cell Ontology (CL)</td>
<td>[CL:0000197](https://www.ebi.ac.uk/ols4/ontologies/cl/classes/http%253A%252F%252Fpurl.obolibrary.org%252Fobo%252FCL_0000197)</td>
</tr>
</table>

Ghrelin Receptor (Ghsr) Neurons is an important cell type in the neurobiology of neurodegenerative diseases. This page provides detailed information about its structure, function, and role in disease processes.

Overview

Neurons expressing ghrelin receptor (GHSR), also known as the growth hormone secretagogue receptor (GHS-R). GHSR is a G protein-coupled receptor that binds ghrelin, the "hunger hormone" produced primarily in the stomach. GHSR neurons are widely distributed in the brain and play critical roles in growth hormone secretion, appetite regulation, energy homeostasis, memory formation, and neuroprotection. GHSR represents a unique target for understanding the link between metabolic state and cognitive function, with important implications for neurodegenerative diseases. [@ghrelin2020]

<!-- multi-taxonomy-enrichment -->

Multi-Taxonomy Classification

Taxonomy Database Cross-References

External Database Links

• [Cell Ontology (CL:0000197)](https://www.ebi.ac.uk/ols4/ontologies/cl/classes/http%253A%252F%252Fpurl.obolibrary.org%252Fobo%252FCL_0000197)
• [OBO Foundry (CL:0000197)](http://purl.obolibrary.org/obo/CL_0000197)
• [Allen Brain Cell Atlas](https://portal.brain-map.org/atlases-and-data/bkp/abc-atlas)
• [CellxGene Census](https://cellxgene.cziscience.com/)
• [Human Cell Atlas](https://www.humancellatlas.org/)

Anatomical Distribution

GHSR-expressing neurons are found throughout the brain with particular density in limbic and hypothalamic regions: [@ghsr2018]

• Hypothalamus:
• Arcuate nucleus (highest density)
• Paraventricular nucleus
• Lateral hypothalamus
• Preoptic area
• Suprachiasmatic nucleus
• Hippocampus:
• Dentate gyrus granule cell layer
• CA1-CA3 pyramidal layers
• Hilus/polymorphic layer
• Cerebral Cortex:
• Prefrontal cortex (layers II-III, V)
• Entorhinal cortex
• Piriform cortex
• Somatosensory cortex
• Ventral Tegmental Area (VTA):
• Dopaminergic neurons
• GABAergic neurons
• Substantia Nigra:
• Pars compacta
• Pars reticulata
• Brainstem:
• Dorsal raphe nucleus
• Locus coeruleus
• Nucleus tractus solitarius
• Amygdala:
• Basolateral complex
• Central nucleus

Molecular Characteristics

GHSR is a 366-amino acid GPCR with unique pharmacological and signaling properties: [@ghrelin2020a]

• Ligands:
• Ghrelin (endogenous agonist, 28 amino acid peptide)
• Ghrelin-like peptide (GPRL-1)
• Synthetic agonists: GHRP-6, hexarelin, MK-677
• Inverse agonists: D-Arg1-D-Phe5-D-Trp7-9-Leu11 substance P
• Signaling pathways:
• Gq/11 coupling to PLC beta leading to IP3/DAG signaling
• ERK1/2 MAPK activation
• PI3K/Akt pathway activation
• Beta-arrestin recruitment
• Constitutive activity: GHSR exhibits high basal activity even without ghrelin binding
• Dimerization: Forms functional dimers with dopamine receptors (D1, D2), melanocortin receptors, and serotonin receptors
• Isoforms: GHSR-1a (functional) and GHSR-1b (truncated, dominant-negative)

Electrophysiology Properties

GHSR neurons display region-specific electrophysiological characteristics: [@ghsr2021]

• Resting membrane potential: -55 to -70 mV
• Input resistance: 200-600 MOhm
• Firing properties:
• Arcuate nucleus GHSR neurons: slow, regular firing (1-3 Hz)
• Hippocampal GHSR neurons: spontaneous activity with burst capability
• VTA GHSR neurons: pacemaker-like firing with dopamine release
• Ghrelin effects: Typically depolarizes neurons via TRPC channel activation
• Plasticity: Ghrelin modulates synaptic plasticity including LTPmechanisms/long-term-potentiation) and LTD

Connectivity

GHSR neurons participate in extensive neural circuits: [@ghrelin2019a]

• Hypothalamic networks:
• Arcuate nucleus to paraventricular nucleus for GH and stress axis control
• Lateral hypothalamus orexin/hypocretin neuron interactions
• Preoptic area for thermoregulation and sleep
• Hippocampal circuits:
• Dentate gyrus to CA3 mossy fiber pathway modulation
• Entorhinal cortex to hippocampal formation input
• Modulation of memory consolidation pathways
• Reward circuitry:
• VTA dopamine neuron modulation
• Nucleus accumbens projections
• Food reward and motivation pathways
• Autonomic centers:
• Brainstem nuclei for vagal integration
• Parabrachial nucleus for satiety signaling

Role in Disease

Alzheimer's Disease (AD)

GHSR neurons have significant implications for Alzheimer's disease: [@ghsr2020]

• Cognitive enhancement: Ghrelin improves memory and reduces amyloid-beta pathology in animal models
• Neuroprotection: GHSR activation protects against Aβ-induced neuronal death via PI3K/Akt and ERK pathways
• Synaptic plasticity: Ghrelin-GHSR signaling enhances LTP in hippocampus
• Metabolic link: GHSR dysfunction may contribute to metabolic aspects of AD
• Therapeutic potential: GHSR agonists being explored as cognitive enhancers in AD

Parkinson's Disease (PD)

• Dopaminergic neurons: GHSR is expressed on VTA and SNc dopamine neurons
• Neuroprotection: Ghrelin protects dopaminergic neurons from MPTP and 6-OHDA toxicity
• Motor function: GHSR activation may improve motor performance in PD models
• Non-motor symptoms: Ghrelin modulates sleep, mood, and autonomic function in PD

Prader-Willi Syndrome (PWS)

• Hyperphagia: GHSR overactivation contributes to uncontrolled eating in PWS
• Genetic link: Chromosome 15q11-q13 deletion includes GHSR regulatory regions
• Therapeutic target: GHSR antagonists being investigated for PWS treatment
• GH deficiency: GHSR agonists used to treat GH deficiency in PWS patients

Depression and Anxiety

• Mood regulation: Ghrelin has antidepressant and anxiolytic-like effects
• Stress response: GHSR activation modulates HPA axis reactivity
• Reward processing: GHSR in VTA affects reward-seeking behavior
• Therapeutic potential: GHSR agonists may have mood-elevating effects

Metabolic Disorders

• Energy homeostasis: GHSR in hypothalamus integrates metabolic signals
• Food intake: Ghrelin-GHSR signaling drives hunger and food-seeking
• Body weight: GHSR antagonists/inverse agonists for obesity treatment
• Ghrelin resistance: Occurs in obesity, altering GHSR signaling

Clinical Significance

GHSR is a therapeutic target for: [@ghrelin2021]

• Alzheimer's disease: GHSR agonists for cognitive enhancement
• Parkinson's disease: GHSR agonists for neuroprotection
• Prader-Willi syndrome: GHSR antagonists for hyperphagia control
• Growth hormone deficiency: GHSR agonists (growth hormone secretagogues)
• Depression: Novel ghanaergic antidepressants
• Obesity: GHSR antagonists/inverse agonists

Research Methods

• Localization: In situ hybridization, immunohistochemistry, GHSR-Cre reporter mice
• Ligand detection: Ghrelin ELISA, mass spectrometry
• Functional studies: Ca2+ imaging, cAMP assays, phosphorylation arrays
• Genetic models: GHSR knockout mice, ghrelin knockout mice
• Optogenetics: GHSR-Cre crossed with optogenetic effectors for circuit mapping
• Behavioral assays: Food intake, memory tests (Morris water maze, novel object recognition), mood tests

Background

The study of Ghrelin Receptor (Ghsr) Neurons has evolved significantly over the past decades. Research in this area has revealed important insights into the underlying mechanisms of neurodegeneration and continues to drive therapeutic development.

Historical context and key discoveries in this field have shaped our current understanding and will continue to guide future research directions.

External Links

• [GHSR Gene (HGNC)](https://www.genenames.org/data/hgnc_data.php?appid=2)
• [GHSR UniProt](https://www.uniprot.org/uniprot/Q9UBU3)
• [GHSR IUPHAR/BPS Guide to Pharmacology](https://www.guidetopharmacology.org/Target.php?humanId=139)
• [PubMed GHSR](https://pubmed.ncbi.nlm.nih.gov/?term=GHSR+ghrelin+neuron)

Pathway Diagram

The following diagram shows the key molecular relationships involving Ghrelin Receptor (GHSR) Neurons discovered through SciDEX knowledge graph analysis: