Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UNIPROT:P61278 (somatostatin)
 22,083 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In the turtle retina the peptides met-enkephalin (metENK), somatostatin (SS), neurotensin (NT), and the indoleamine serotonin (5-HT) modulate ganglion cell (GC) activity. The predominant action of the peptides is excitatory, generally enhancing spontaneous firing and light-evoked activity. In contrast, 5-HT usually inhibits these GC activities. MetENK has both direct synaptic input onto GC and indirect action possibly via a GABA inhibitory interneuron. The metENK actions appear mediated via a mu-opiate receptor; morphine and D-ala-metENK-amide (DALA), a stable analog of metENK, are agonists. Naloxone antagonizes the actions of metENK and its agonists. DALA occasionally inhibits GC. This inhibition is antagonized by picrotoxin, while concurrent excitatory action on GC is enhanced. DALA enhances GC response at high spatial frequencies; naloxone attenuates it. The enhancement by DALA suggests a narrowed receptive-field (RF) center, possibly due to changes in a GABA-mediated inhibitory surround. 5-HT inhibitory actions are also mediated via direct and indirect synaptic pathways. 5-methoxy-dimethyl-tryptamine and methoxy-phenyl-piperazine are agonists of 5-HT action. They are both specific 5-HT1 agonists. LSD (lysergic acid diethylamide) and cyproheptadine, which act on 5-HT2 receptors, antagonize 5-HT actions in this retina. Strychnine enhances GC activity, probably by antagonizing glycine-mediated inhibitory inputs. It does not block the inhibitory action of 5-HT, which suggests that the indirect 5-HT inhibition is not mediated via a glycinergic interneurone. 5-HT suppresses directional selectivity (DS) and attenuates high spatial frequencies in some GC. This may be mediated via inhibition of GABAergic amacrines subserving DS and the RF inhibitory surround.
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PMID:Pharmacological actions of peptides and indoleamines on turtle retinal ganglion cells. 257 68

Fibroblasts were examined for specific binding sites of ten putative neurotransmitters to determine whether this tissue could be used in receptor studies of neurologic and psychiatric disorders. Stereospecific saturable binding was not found for any of the ligands: arginine vasopressin, neurotensin, somatostatin, angiotensin II, thyrotropin-releasing hormone (TRH), alpha-bungarotoxin, LSD, dihydromorphine, muscimol and spiperone.
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PMID:Absence of specific binding of several putative neuro-transmitters to human fibroblasts. 613 66

The noradrenergic neurones of the autonomic nervous system (postganglionic sympathetic neurones) and of the central nervous system are endowed with presynaptic receptors by which noradrenaline release is inhibited by noradrenaline itself (via the alpha2-autoreceptor) and by other transmitters and mediators (via heteroreceptors). Frequently, but not consistently, inhibitory interactions exist between auto- and heteroreceptors. This holds true for the following heteroreceptors: adenosine A1, cannabinoid CB1, dopamine D2/D3, histamine H3, 5-hydroxytryptamine (serotonin) 5-HT(1B), imidazoline, muscarine M2, delta opioid, kappa opioid, mu opioid, orphan opioid (ORL1), prostaglandin EP3, and somatostatin SRIF1. Such interactions (which have also been obtained in human tissue) may, if not considered, prevent the identification of a putative heteroreceptor or the quantitative estimation of the effect mediated by this receptor, and they may explain drug interactions in humans in vivo; many ligands at the alpha2-autoreceptor and at the heteroreceptors may be simultaneously used for therapeutic reasons (e.g., carbachol, clonidine, dopamine, sumatriptan, mianserin, and misoprostol) or abused (e.g., heroin, LSD, and delta9-tetrahydrocannabinol in hashish or marijuana).
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PMID:Interactions between the presynaptic alpha2-autoreceptor and presynaptic inhibitory heteroreceptors on noradrenergic neurones. 982 Jul 29

Characterization of both neurochemical phenotype of G protein-coupled receptor (GPCR)-expressing cells and receptor compartmentalization is a prerequisite for the elucidation of receptor functions in the central nervous system. However, it is often prevented by the diffuse and homogeneous distribution of receptor immunoreactivity. This is particularly true for the somatostatin (SRIF) sst2A receptor, which is largely distributed in the mammalian brain. By using this receptor as a model, we investigated whether receptor internalization, a biochemical property shared by numerous GPCRs, would reveal sst2A-expressing cell populations in the rat dorsolateral septum (LSD), a region in which SRIF might play an important modulatory role. Thirty minutes to 1 hour after intracerebroventricular injection of the sst2A receptor agonist octreotide, numerous sst2A-immunoreactive neurons and processes became apparent due to intracytoplasmic accumulation of intensely stained granules. Double-immunolabeling experiments with synaptophysin and MAP2 provided evidence that internalized sst2A receptors are predominantly localized in the somatodendritic compartment. Revealing sst2A receptor-expressing cell bodies permitted to analyze their neurotransmitter content. Quantitative analysis demonstrated an extensive overlap (approximately 85%) between SRIF- and sst2A-expressing neuronal populations. Additionally, numerous SRIF-immunoreactive axon-like terminals were found in close apposition with sst2A-positive cell bodies and dendrites. Taken together, these data suggest that the sst2A receptor is predominantly expressed in LSD neurons as a postsynaptic autoreceptor, thus providing novel neuroanatomic clues to elucidate SRIF neurotransmission in this region. More generally, in vivo agonist-induced internalization appears as a rapid and powerful tool for the neurochemical characterization of GPCR-expressing cell populations in the mammalian brain.
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PMID:Neurochemical characterization of receptor-expressing cell populations by in vivo agonist-induced internalization: insights from the somatostatin sst2A receptor. 1241 43