UNIPROT:P61278 - FACTA Search

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)

Sharp pain is conducted rapidly by myelinated delta A fibers and diffused pain slowly by nonmyelinated C fibers to pseudobipolar neurons in the posterior ganglion and from there to neurons located in the posterolateral horn of the spinal cord. From here on nociferous impulses are transmitted by excitatory peptides (e.g. substance P) or amino acids (e.g. glutamate, aspartate) through interconnecting neurons of the pain pathways, primarily on the contralateral side, to the brain stem and from there to the sensory cortex, where they are appreciated and acted upon. There are specific inhibitory receptors located on axon terminals, near to the release sites of the excitatory amino acids and peptides. Stimulation of these receptors by their appropriate ligands such as endogenous (e.g. enkephalis, endorphins) or exogenous opioids, clonidine, serotonin, somatostatin inhibits the release of excitatory neurotransmitters and relieves pain. There are at least 3 different opioid receptors, called mu-, kappa- and delta-receptors in the spinal cord. These can be differentiated from one another by their specific affinity toward different endogenous or exogenous opioids and the pure narcotic antagonist, naloxone. It appears that the nociferous impulses transmitted by parallel pathways equipped with different inhibitory receptors have to be integrated to produce pain sensation and partial inhibition of transmission in different pathways or complete inhibition in one of the pathways may relieve pain. In recent years the concept of "selective spinal analgesia" has been applied clinically for the relief of postoperative, obstetrical and chronic pain. At first it was expected that the intrathecal or peridural administration of morphine will produce analgesia without the side effects of systemically administered morphine. It soon became evident, however, that intrathecally and peridurally administered morphine after several hours of delay reaches the fourth ventricle and by stimulating mu-receptors may cause respiratory depression and other undesired effects (e.g. nausea, vomiting, pruritus). Several different approaches are being investigated for the production of selective spinal analgesia without side effects. They include: a. the use of more lipophilic, long-lasting opioids (e.g. lofentanil) which would be almost completely absorbed by the spinal cord and therefore would not reach the medullary centers; b. the development of opioids with specific affinity to kappa- and for delta- and little or no affinity to mu-receptors, primarily responsible for side effects; and c. combining lower doses of opioid agonists with alpha 2-adrenergic agonists (e.g. clonidine) or with somatostatin. It is conceivable that in the not-too-distant future, it will be possible to achieve through these measures, selective spinal analgesia without side effects.
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PMID:Pain control with intrathecally and peridurally administered opioids and other drugs. 168 73

Substance P-like and somatostatin-like immunoreactivities (SPLI and SLI) were determined in ventricular fluid of patients with chronic pain syndromes and in a comparison group with multiple sclerosis, essential tremor, epilepsy and postanoxic myoclonus. Concentrations of SPLI and SLI were non-significantly decreased by 40% and 33% in chronic pain patients as compared with control patients without pain. There were no differences apparent between subgroups of pain patients (deafferentation pain, neoplasia-induced pain, thalamic pain). High pressure liquid chromatography combined with radioimmunoassay showed marked heterogeneity of SPLI and SLI.
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PMID:Substance P-like immunoreactivity and somatostatin-like immunoreactivity in the ventricular fluid of patients with chronic pain syndromes. 183 80

In an in vivo saline perfusate of the intrathecal space of 6 dogs, the concentration of somatostatin was determined by radioimmunoassay before and over 2 h after epidural administration of 3 mg somatostatin. The total recovered amount of somatostatin was negligible, about 0.02%. However, within 50 min after the bolus epidural injection of somatostatin, the concentration per ml perfusate increased from 0.1 +/- 0.02 ng/ml to 138 +/- 102 ng/ml (P less than 0.001) and declined to 4 +/- 1.7 ng/ml after 120 min. This increase of the somatostatin concentration by 3 orders of magnitude might explain why epidurally administered somatostatin is effective in treatment of acute and chronic pain. In a control investigation with epidural morphine in another 6 dogs to prove the feasibility of the method, the total recovered amount of morphine in the intrathecal perfusate over 2 h was about 12%.
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PMID:Permeability of epidural somatostatin and morphine into the intrathecal space of dogs. 286 50

We evaluated the concentration of the neuropeptide somatostatin (SOM) in the CSF of patients with several neurologic diseases. Since SOM is localized in high concentrations in primary sensory pathways, such as the dorsal root ganglia and dorsal horn of the spinal cord, it might be involved in conditions of chronic pain due to functional alterations of nociceptive neurons, such as postinfectious zoster neuralgia. Our study indicated a marked elevation of SOM in patients suffering from postzoster neuralgia compared with controls. Comparison with other neurologic diseases revealed decreased CSF SOM levels in Parkinson's and Alzheimer's disease, unchanged values in patients with amyotrophic lateral sclerosis, and increased concentrations in patients with brain tumors. In neurodegenerative disorders, SOM levels in CSF seemed to reflect the anatomic distribution as well as a reduction or preservation of the peptide in certain brain areas affected by the disease process. In postzoster patients, postinfectious degeneration of dorsal root ganglia cells might cause deafferentation of dorsal horn neurons and activation of SOM-containing systems with increased release either locally from neurons in the dorsal horn of the spinal cord or from descending fiber projections. The results suggested that SOM may take part in the modulation of nociceptive responses.
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PMID:CSF somatostatin is elevated in patients with postzoster neuralgia. 290 Oct 53

Concentrations of somatostatin-like immunoreactivity in cerebrospinal fluid were significantly reduced in chronic pain patients compared to control patients without chronic pain. This difference was not influenced by demographic or clinical characteristics. Somatostatin has been shown to be a neurotransmitter in animal nociception; pharmacologic doses of this substance have moderated human pain. Our findings provide evidence that somatostatin may be involved in the pathogenesis of the chronic pain state.
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PMID:Alterations in cerebrospinal fluid concentrations of somatostatin-like immunoreactivity in chronic pain patients. 296 47

To study the hormonal perturbations in FMS patients we injected sixteen FMS patients and seventeen controls a cocktail of the hypothalamic releasing hormones: Corticotropin-releasing hormone (CRH), Thyrotropin-releasing hormone (TRH), Growth hormone-releasing hormone (GHRH), and Luteinizing hormone-releasing hormone (LHRH) and observed the hormonal secretion pattern of the pituitary together with the hormones of the peripheral endocrine glands. We found in FMS patients elevated basal values of ACTH and cortisol, lowered basal values of insulin-like growth factor I (IGF-I) and of triiodothyronine (T3), elevated basal values of follicle-stimulating hormone (FSH) and lowered basal values of estrogen. Following injection of the four releasing-hormones, we found in FMS patients an augmented response of ACTH, a blunted response of TSH, while the prolactin response was exaggerated. The effects of LHRH stimulation were investigated in six FMS patients and six controls and disclosed a significantly blunted response of LH in FMS. We explain the deviations of hormonal secretion in FMS patients as being caused by chronic stress, which, after being perceived and processed by the central nervous system (CNS), activates hypothalamic CRH neurons. CRH, on the one hand, activates the pituitary-adrenal axis, but also stimulates at the hypothalamic level somatostatin secretion which, in turn, causes inhibition of GH and TSH at the pituitary level. The suppression of gonadal function may also be attributed to elevated CRH by its ability to inhibit hypothalamic LHRH release, although it could act also directly on the ovary by inhibiting FSH-stimulated estrogen production. We conclude that the observed pattern of hormonal deviations in FMS patients is a CNS adjustment to chronic pain and stress, constitutes a specific entity of FMS, and is primarily evoked by activated CRH neurons.
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PMID:Secretory pattern of GH, TSH, thyroid hormones, ACTH, cortisol, FSH, and LH in patients with fibromyalgia syndrome following systemic injection of the relevant hypothalamic-releasing hormones. 1002 90

The symptomatology of the fibromyalgia syndrome (FMS) often resembles an alteration in central nervous set points at least in three systems. The patients suffer under chronic pain in the region of the locomotor system, presumably reflecting a disturbed central processing of pain. Anxiety and depression often characterizes the clinical picture. Almost all of the hormonal feedback mechanisms controlled by the hypothalamus are altered. Characteristic for FMS patients are the elevated basal values of ACTH, follicle-stimulating hormone (FSH), and cortisol as well as lowered basal values of insulin-like growth factor 1 (IGF-1, somatomedin C), free triiodothyronine (FT3), and oestrogen. In FMS patients, the systemic administration of the relevant releasing hormones of corticotropin-releasing hormone (CRH), growth hormone-releasing hormone (GHRH), thyreotropin-releasing hormone (TRH), and luteinizing hormone-releasing hormone (LHRH) leads to increased secretion of ACTH and prolactin, whereas the degree to which TSH can be stimulated is reduced. The stimulation of the hypophysis with LHRH in female FMS patients during their follicular phase results in a significantly reduced LH response. All in all, the typical alterations in set points of hormonal regulation that are typical for FMS patients can be explained as a primary stress activation of hypothalamic CRH neurons caused by the chronic pain. In addition to the stimulation of pituitary ACTH secretion, CRH activates somatostatin on the hypothalamic level, which in turn inhibits the release of GH and TSH on the hypophyseal level. The lowered oestrogen levels could be accounted for both via an inhibitory effect of the CRH on the hypothalamic release of LHRH or via a direct CRH-mediated inhibition of the FSH-stimulated oestrogen production in the ovary. Serotonin (5HT), precursors like tryptophan (5HTP), drugs which release 5HT or act directly on 5HT receptors stimulate HPA axis, indicating a stimulatory serotonergic influence on HPA axis function. Therefore activation of the HPA axis may reflect an elevated serotonergic tonus in the central nervous system of FMS patients.
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PMID:Neuroendocrine and hormonal perturbations and relations to the serotonergic system in fibromyalgia patients. 1102 24

A large body of data from a number of different laboratories worldwide has demonstrated a general tendency for reduced adrenocortical responsiveness in CFS. It is still not clear if this is secondary to CNS abnormalities leading to decreased activity of CRH- or AVP-producing hypothalamic neurons. Primary hypofunction of the CRH neurons has been described on the basis of genetic and environmental influences. Other pathways could secondarily influence HPA axis activity, however. For example, serotonergic and noradrenergic input acts to stimulate HPA axis activity. Deficient serotonergic activity in CFS has been suggested by some of the studies as reviewed here. In addition, hypofunction of sympathetic nervous system function has been described and could contribute to abnormalities of central components of the HPA axis. One could interpret the clinical trial of glucocorticoid replacement in patients with CFS as confirmation of adrenal insufficiency if one were convinced of a positive therapeutic effect. If patient symptoms were related to impaired activation of central components of the axis, replacing glucocorticoids would merely exacerbate symptoms caused by enhanced negative feedback. Further study of specific components of the HPA axis should ultimately clarify the reproducible abnormalities associated with a clinical picture of CFS. In contrast to CFS, the results of the different hormonal axes in FMS support the assumption that the distortion of the hormonal pattern observed can be attributed to hyperactivity of CRH neurons. This hyperactivity may be driven and sustained by stress exerted by chronic pain originating in the musculoskeletal system or by an alteration of the CNS mechanism of nociception. The elevated activity of CRH neurons also seems to cause alteration of the set point of other hormonal axes. In addition to its control of the adrenal hormones, CRH stimulates somatostatin secretion at the hypothalamic level, which, in turn, causes inhibition of growth hormone and thyroid-stimulating hormone at the pituitary level. The suppression of gonadal function may also be attributed to elevated CRH because of its ability to inhibit hypothalamic luteinizing hormone-releasing hormone release; however, a remote effect on the ovary by the inhibition of follicle-stimulating hormone-stimulated estrogen production must also be considered. Serotonin (5-HT) precursors such as tryptophan (5-HTP), drugs that release 5-HT, or drugs that act directly on 5-HT receptors stimulate the HPA axis, indicating a stimulatory effect of serotonergic input on HPA axis function. Hyperfunction of the HPA axis could also reflect an elevated serotonergic tonus in the CNS of FMS patients. The authors conclude that the observed pattern of hormonal deviations in patients with FMS is a CNS adjustment to chronic pain and stress, constitutes a specific entity of FMS, and is primarily evoked by activated CRH neurons.
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PMID:Neuroendocrine perturbations in fibromyalgia and chronic fatigue syndrome. 1108 55

The peptide somatostatin [somatotropin release-inhibiting factor (SRIF)] is widely distributed in the body and exerts a variety of hormonal and neural actions. Several lines of evidence indicate that SRIF is important in nociceptive processing: (1) it is localized in a subset of small-diameter dorsal root ganglion cells; (2) activation of SRIF receptors results in inhibition of both nociceptive behaviors in animals and acute and chronic pain in humans; (3) SRIF inhibits dorsal horn neuronal activity; and (4) SRIF reduces responses of joint mechanoreceptors to noxious rotation of the knee joint. The goal of the present study is to show that cutaneous nociceptors are under the tonic inhibitory control of SRIF. This is accomplished using behavioral and electrophysiological paradigms. In a dose-dependent manner, intraplantar injection of the SRIF receptor antagonist cyclo-somatostatin (c-SOM) results in nociceptive behaviors in normal animals and enhancement of nociceptive behaviors in formalin-injected animals, and these actions can be blocked when c-SOM is coapplied with three different SRIF agonists. Furthermore, intraplantar injection of SRIF antiserum also results in nociceptive behaviors. Electrophysiological recordings using an in vitro glabrous skin-nerve preparation show increased nociceptor activity in response to c-SOM, and this increase is blocked by the same three SRIF agonists. Parallel behavioral and electrophysiological studies using the opioid antagonist naloxone demonstrate that endogenous opioids do not maintain a tonic inhibitory control over peripheral nociceptors, nor does opioid receptor antagonism influence peripheral SRIF effects on nociceptors. These findings demonstrate that SRIF receptors maintain a tonic inhibitory control over peripheral nociceptors, and this may contribute to mechanisms that control the excitability of these terminals.
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PMID:Tonic control of peripheral cutaneous nociceptors by somatostatin receptors. 1135 91

The present article concentrates on mechanisms that lead to the excitation of nociceptors in soft tissues and nociceptive neurones in the spinal dorsal horn. These mechanisms may contribute to the so-called unspecific low back pain. Properties of nociceptors in soft tissues: A nociceptive ending in soft tissue contains a multitude of receptor molecules in its membrane. The molecular receptors include binding sites for algesic substances that are released during painful stimulation or pathologic alterations of the tissue: bradykinin (BK), serotonin (5-HT), prostaglandin E2 (PG E2), adenosine triphosphate (ATP) and protons (H(+)). The excitation and sensitisation of nociceptors by these substances can be explained by the binding of the substances to the receptor molecules in the membrane of the receptive ending and ensuing opening of ion channels or activation of metabolic cascades. Purinergic receptor molecules in the membrane of nociceptors are activated by ATP. These receptors may be of particular importance for deep somatic pain, because ATP is present in large amounts in muscle tissue and is released during muscle damage. ATP-sensitive nociceptors appear to be distinct from nociceptors that can be excited by protons. The conduction of nociceptive information from muscle to the spinal cord is partly carried by unmyelinated fibres that possess tetrodotoxin-resistant (TTX-r) Na(+)-channels. Therefore, a drug that specifically blocks TTX-r Na(+)-channels would be a new attractive tool in the treatment of patients with deep somatic pain. Chronic muscle lesions such as a myositis have been shown to be associated with a higher innervation density of the tissue with free nerve endings that contain the neuropeptide substance P (SP). Many of these endings are likely to be nociceptors. Since a painful stimulus that acts on a muscle with increased nociceptor density will excite more nociceptors and elicit more pain, the increase in nociceptor density constitutes a peripheral mechanism for hyperalgesia. In muscle free nerve endings - many of which are nociceptive - the neuropeptides SP, calcitonin gene-related peptide (CGRP) and somatostatin have been shown to be present. These substances are released from the receptive endings in muscle when they are stimulated. SP and CGRP have a strong effect on blood vessels and induce local vasodilatation and oedema. The local oedema in the vicinity of the nociceptor is associated with the release of BK from plasma proteins, which increases the excitability of the nerve ending (see below). Thus, a local vicious cycle forms that may contribute to the formation of trigger points. Sensitisation of nociceptors and peripheral hyperalgesia: Nociceptors are easily sensitised, i.e. following a conditioning stimulus they are more sensitive to the unconditioned stimulus. In animals and humans, the responses to injections of BK can be increased by 5-HT or PG E2. The responses of muscle nociceptors to mechanical stimuli are likewise enhanced after administration of BK. During overuse, ischemia or inflammation of soft tissues, the tissue concentrations of BK, PG E2, and 5-HT are elevated and sensitise muscle nociceptors. A sensitised nociceptor is excited and elicits pain when innocuous mechanical stimuli act on the muscle, e.g. during contractions or stretch. Therefore, in chronically altered soft tissues, weak everyday stimuli are likely to cause pain. Mechanisms at the spinal level: In experiments on rats in which a myositis of the gastrocnemius-soleus (GS) muscle was induced experimentally, the effects of a peripheral painful lesion on the discharge behaviour of sensory dorsal horn neurones were studied. One of the main effects of the myositis was an expansion of the input (target) region of the muscle nerve, i.e. the population of dorsal horn neurones responding to an electrical standard stimulus applied to the GS muscle nerve grew larger. One reason for the myositis-induced expansion of the input region is hyperexcitability of the neurones caused by the release of SP and glutamate from the spinal terminals of muscle afferents with ensuing activation of NMDA channels in dorsal horn neurones (central sensitisation). The central sensitisation is of clinical importance because it can explain the hyperalgesia and spread of pain in patients. In contrast to excitability, the resting activity of dorsal horn neurones - which is likely to induce spontaneous pain in patients - does not appear to depend on the release of SP and glutamate but on the concentration of nitric oxide (NO) in the spinal cord. A pharmacological block of the NO synthesis led to a significant increase in background activity without affecting the excitability of the dorsal horn neurones. Such an increase in background activity was observed exclusively in nociceptive neurones, i.e. a local lack of NO in the spinal cord induces spontaneous pain. According to data from animal experiments, a decrease in the spinal NO concentration occurs as a sequel of a chronic muscle lesion; therefore, a lack of NO is a probable factor for the induction of chronic spontaneous pain. Normally, lesion-induced pain subsides and does not develop into chronic pain. The mechanisms governing the return to normal neuronal behaviour after a peripheral lesion are not well studied. Probably, the activation of inhibitory mechanisms, e.g. increased spinal synthesis of GABA or elevated activity of the descending antinociceptive system contribute to the restoration of normal function. The final step in the transition from acute to chronic pain are structural changes that perpetuate the functional changes. In the rat myositis model, an increase in the number of synapses on the surface of NO-snythesizing cells was present 8 h following induction of the myositis. These data show that structural changes appear quite early in the development of a painful disorder. A novel hypothesis for the development of chronic pain states that a strong nociceptive input to the spinal cord leads to cell death predominantly in inhibitory interneurones. Most of these interneurones are assumed to be tonically active; when their number decreases, the nociceptive neurones are chronically disinhibited and elicit continuous pain also in the absence of a noxious stimulus.
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PMID:[Pathophysiology of low back pain and the transition to the chronic state - experimental data and new concepts]. 1179 44

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