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

1. In this study we have examined the effects of nociceptin, an endogenous ligand for the opioid-like receptor ORL1 on the membrane properties of rat locus coeruleus (LC) neurones in vitro, using intracellular and whole cell patch clamp recording. 2. When locus coeruleus neurones were voltage clamped to -60 mV, application to nociceptin caused an outward current in all cells examined (n = 49), with an EC50 of 90 nM. Neither the potency nor the maximal effect of nociceptin was altered in the presence of the peptidase inhibitors, bestatin (20 microM) or thiorphan (2 microM). 3. The outward currents caused by nociceptin in 2.5 mM extracellular K+ reversed polarity at -123 mV, more negative than the predicted K+ reversal potential of -105 mV. Increasing extracellular K+ to 6.5 mM resulted in a shift of the reversal potential of +25 mV, a shift consistent with a K+ conductance. The conductance activated by nociceptin showed mild inward rectification. 4. Application of a high concentration of nociceptin (3 microM) occluded the current produced by simultaneous application of high concentrations of Met-enkephalin (10 microM), (3 microM) somatostatin and UK 14304 (3 microM), indicating that nociceptin activated the same conductance as mu-opioid and somatostatin receptors and alpha 2-adrenoceptors. 5. The actions of nociceptin were weakly antagonized by the opioid antagonist, naloxone, with pKb's estimated from 2 cells of -4.23 and -4.33. The mu-opioid antagonist, CTAP (D-Phe-Cys-Tyr-D-Trp-Arg-Pen-Thr-NH2, 1 microM), the opioid antagonist, nalorphine (30 microM) or the somatostatin antagonist, CPP (cyclo(7-aminoheptanoyl-Phe-D-Trp-Lys-Thr[Bz1]) 3 microM) did not affect the nociceptin-induced current. 6. Dynorphin A (microM), another putative endogenous ligand for ORL1, caused a robust outward current in locus coeruleus neurones that was, however, completely antagonized by moderate concentrations of naloxone (300 nM-1 microM). 7. Continuous application of nociceptin (3 microM) resulted in a decrease of the outward current to a steady level of 70% of the maximum response with a t1/2 of 120s. Desensitization was largely homologous because simultaneous application of Met-enkephalin (30 microM) during the desensitized period of the nociceptin response resulted in an outward current that was 92% of control responses to Met-enkephalin in the same cells. Conversely, continuous application of Met-enkephalin (30 microM) resulted in a decrease of Met-enkephalin current to a steady level that was 54% of the initial current. During this desensitized period application of nociceptin (3 microM) resulted in a current that was 78% of the control responses to nociceptin in the same cells. 8. Thus nociceptin potently activates an inwardly rectifying K+ conductance in locus coeruleus neurones, with a pharmacological profile consistent with activation of the ORL1 receptor. Dynorphin A does not appear to be a ligand for ORL1 in rat locus coeruleus neurones.
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PMID:Nociceptin receptor coupling to a potassium conductance in rat locus coeruleus neurones in vitro. 898 9

Neuropeptides are signaling molecules that interact with G-protein coupled receptors located both pre- and postsynaptically. Presynaptically, these receptors are localized in axons and terminals away from presynaptic specializations. Neuropeptides are stored in dense core vesicles that are distinct from the clear synaptic vesicles containing classic neurotransmitters such as glutamate and GABA. Because they require a stronger Ca(2+) signal than synaptic vesicles, dense core vesicles do not release neuropeptides with single action potentials but rather require high-frequency trains. Thus, neuropeptides only modulate strongly stimulated synapses, providing negative or positive feedback. Many neuropeptides have been found to inhibit glutamate release from presynaptic terminals, and the major mechanism is likely direct interaction of betagamma G-protein subunits with presynaptic proteins such as SNARE (soluble N-ethylmaleimide-sensitive factor attachment protein receptor). The use of mouse genetic models and specific receptor antagonists are beginning to unravel the function of inhibitory neuropeptides. The opioid receptors kappa and mu, which are activated by endogenous opioid peptides such as dynorphin, enkephalin, and possibly the endomorphins, are important in modulating pain transmission. Dynorphin, nociceptin/orphanin FQ, and somatostatin and its related peptide cortistatin appear to play a role in modulation of learning and memory. Neuropeptide Y has important functions in ingestive behavior and also in entraining circadian rhythms. The existence of neuropeptides greatly expands the computational ability of the brain by providing additional levels of modulation.
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PMID:Presynaptic inhibition of glutamate release by neuropeptides: use-dependent synaptic modification. 1755

There are several lines of evidence that indicate a prominent role for the opioid system in the acquisition and consolidation of learned associations. Specifically, kappa opioid receptor (KOR) modulation has been demonstrated to alter various behavioral tasks including whisker trace eyeblink conditioning (WTEB). WTEB is an associative conditioning paradigm in which a neutral conditioned stimulus (CS; Whisker stimulation) is paired following a short stimulus free trace interval with a salient unconditioned stimulus that elicits a blink response (US; Eye shock). Work from our laboratory has shown that WTEB conditioning is dependent upon and induces plasticity in primary somatosensory cortex (S1), a likely site for memory storage. Our subsequent studies have shown that WTEB acquisition or consolidation are impaired when the initial or later phase of KOR activation in S1 is respectively blocked. Interestingly, this mechanism by which KOR is activated in S1 during learning remains unexplored. Dynorphin (DYN), KOR's endogenous ligand, is synthesized from the precursor prodynorphin (PD) that is synthesized from preprodynorphin (PPD). In S1, most PPD is found in inhibitory GABAergic somatostatin interneurons (SOM), suggesting that these SOM interneurons are upstream regulators of learning induced KOR activation. Using immunofluorescence to investigate the expression of PD and SOM, the current study found that PD/SOM expression was transiently increased in S1 during learning. Interestingly, these findings have direct implications towards a time- and learning-dependent role for KOR activation in neocortical mechanisms mediating learning.
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PMID:Neocortical prodynorphin expression is transiently increased with learning: Implications for time- and learning-dependent neocortical kappa opioid receptor activation. 2880 36


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