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Hagan DW, Ferreira SM, Santos GJ, Phelps EA. The role of GABA in islet function. Front Endocrinol (Lausanne) 2022; 13:972115. [PMID: 36246925 PMCID: PMC9558271 DOI: 10.3389/fendo.2022.972115] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/17/2022] [Accepted: 08/29/2022] [Indexed: 11/13/2022] Open
Abstract
Gamma aminobutyric acid (GABA) is a non-proteinogenic amino acid and neurotransmitter that is produced in the islet at levels as high as in the brain. GABA is synthesized by the enzyme glutamic acid decarboxylase (GAD), of which the 65 kDa isoform (GAD65) is a major autoantigen in type 1 diabetes. Originally described to be released via synaptic-like microvesicles or from insulin secretory vesicles, beta cells are now understood to release substantial quantities of GABA directly from the cytosol via volume-regulated anion channels (VRAC). Once released, GABA influences the activity of multiple islet cell types through ionotropic GABAA receptors and metabotropic GABAB receptors. GABA also interfaces with cellular metabolism and ATP production via the GABA shunt pathway. Beta cells become depleted of GABA in type 1 diabetes (in remaining beta cells) and type 2 diabetes, suggesting that loss or reduction of islet GABA correlates with diabetes pathogenesis and may contribute to dysfunction of alpha, beta, and delta cells in diabetic individuals. While the function of GABA in the nervous system is well-understood, the description of the islet GABA system is clouded by differing reports describing multiple secretion pathways and effector functions. This review will discuss and attempt to unify the major experimental results from over 40 years of literature characterizing the role of GABA in the islet.
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Affiliation(s)
- D. Walker Hagan
- J. Crayton Pruitt Family Department of Biomedical Engineering, University of Florida, Gainesville, FL, United States
| | - Sandra M. Ferreira
- J. Crayton Pruitt Family Department of Biomedical Engineering, University of Florida, Gainesville, FL, United States
| | - Gustavo J. Santos
- Islet Biology and Metabolism Lab – I.B.M. Lab, Department of Physiological Sciences, Center of Biological Sciences, Federal University of Santa Catarina - UFSC, Florianópolis, Brazil
| | - Edward A. Phelps
- J. Crayton Pruitt Family Department of Biomedical Engineering, University of Florida, Gainesville, FL, United States
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2
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Amair-Pinedo F, Matos I, Saurí T, Hernando J, Capdevila J. The Treatment Landscape and New Opportunities of Molecular Targeted Therapies in Gastroenteropancreatic Neuroendocrine Tumors. Target Oncol 2018; 12:757-774. [PMID: 29143176 DOI: 10.1007/s11523-017-0532-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Neuroendocrine neoplasms (NENs) are a heterogeneous group of neoplasms that originate from neuroendocrine stem cells and express both neural and endocrine markers. They are found in almost every organ, and while NENs are mostly associated with slow growth, complications due to the uncontrolled secretion of active peptides, and metastatic disease, may significantly impair the quality of life and can ultimately lead to the death of affected individuals. Expanding knowledge of the genetic, epigenetic, and proteomic landscapes of NENs has led to a better understanding of their molecular pathology and consequently increased treatment options for patients. Here, we review the principal breakthroughs in NEN treatment management, owing largely to omics technologies over the last few years, current recommendations of systemic treatment, and ongoing research into the identification of predictive and response biomarkers based on molecular targeted therapies.
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Affiliation(s)
| | - Ignacio Matos
- Vall d'Hebron University Hospital, Barcelona, Spain.,Vall d'Hebron Institute of Oncology (VHIO), Barcelona, Spain
| | - Tamara Saurí
- Vall d'Hebron University Hospital, Barcelona, Spain.,Vall d'Hebron Institute of Oncology (VHIO), Barcelona, Spain
| | - Jorge Hernando
- Vall d'Hebron University Hospital, Barcelona, Spain.,Vall d'Hebron Institute of Oncology (VHIO), Barcelona, Spain
| | - Jaume Capdevila
- Vall d'Hebron University Hospital, Barcelona, Spain. .,Vall d'Hebron Institute of Oncology (VHIO), Barcelona, Spain.
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3
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Lambert GA, Zagami AS. Does somatostatin have a role to play in migraine headache? Neuropeptides 2018; 69:1-8. [PMID: 29751998 DOI: 10.1016/j.npep.2018.04.006] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/09/2018] [Revised: 03/05/2018] [Accepted: 04/15/2018] [Indexed: 11/24/2022]
Abstract
Migraine is a condition without apparent pathology. Its cardinal symptom is the prolonged excruciating headache. Theories about this pain have posited pathologies which run the gamut from neural to vascular to neurovascular, but no observations have detected a plausible pathology. We believe that no pathology can be found for migraine headache because none exists. Migraine is not driven by pathology - it is driven by neural events produced by triggers - or simply by neural noise- noise that has crossed a critical threshold. If these ideas are true, how does the pain arise? We hypothesise that migraine headache is a consequence of withdrawal of descending pain control, produced by "noise" in the cerebral cortex. Nevertheless, there has to be a neural circuit to transform cortical noise to withdrawal of pain control. In our hypothesis, this neural circuit extends from the cortex, synapses in two brainstem nuclei (the periaqueductal gray matter and the raphe magnus nucleus) and ultimately reaches the first synapse of the trigeminal sensory system. The second stage of this circuit uses serotonin (5HT) as a neurotransmitter, but the neuronal projection from the cortex to the brainstem seems to involve relatively uncommon neurotransmitters. We believe that one of these is somatostatin (SST). Temporal changes in levels of circulating SST mirror the temporal changes in the incidence of migraine, particularly in women. The SST2 receptor agonist octreotide has been used with some success in migraine and cluster headache. A cortical to PAG/NRM neural projection certainly exists and we briefly review the anatomical and neurophysiological evidence for it and provide preliminary evidence that SST may the critical neurotransmitter in this pathway. We therefore suggest that the withdrawal of descending tone in SST-containing neurons, might create a false pain signal and hence the headache of migraine.
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Affiliation(s)
- Geoffrey A Lambert
- Prince of Wales Clinical School, UNSW, Australia; School of Medicine, University of Western Sydney, Australia.
| | - Alessandro S Zagami
- Prince of Wales Clinical School, UNSW, Australia; Institute of Neurological Sciences, Prince of Wales Hospital, Australia
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4
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Cives M, Simone V, Rizzo FM, Silvestris F. NETs: organ-related epigenetic derangements and potential clinical applications. Oncotarget 2016; 7:57414-57429. [PMID: 27418145 PMCID: PMC5302998 DOI: 10.18632/oncotarget.10598] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2016] [Accepted: 06/30/2016] [Indexed: 12/15/2022] Open
Abstract
High-throughput next-generation sequencing methods have recently provided a detailed picture of the genetic landscape of neuroendocrine tumors (NETs), revealing recurrent mutations of chromatin-remodeling genes and little-to-no pathogenetic role for oncogenes commonly mutated in cancer. Concurrently, multiple epigenetic modifications have been described across the whole spectrum of NETs, and their putative function as tumorigenic drivers has been envisaged. As result, it is still unclear whether or not NETs are epigenetically-driven, rather than genetically-induced malignancies. Although the NET epigenome profiling has led to the identification of molecularly-distinct tumor subsets, validation studies in larger cohorts of patients are needed to translate the use of NET epitypes in clinical practice. In the precision medicine era, recognition of subpopulations of patients more likely to respond to therapeutic agents is critical, and future studies testing epigenetic biomarkers are therefore awaited. Restoration of the aberrant chromatin remodeling machinery is an attractive approach for future treatment of cancer and in several hematological malignancies a few epigenetic agents have been already approved. Although clinical outcomes of epigenetic therapies in NETs have been disappointing so far, further clinical trials are required to investigate the efficacy of these drugs. In this context, given the immune-stimulating effects of epidrugs, combination therapies with immune checkpoint inhibitors should be tested. In this review, we provide an overview of the epigenetic changes in both hereditary and sporadic NETs of the gastroenteropancreatic and bronchial tract, focusing on their diagnostic, prognostic and therapeutic implications.
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Affiliation(s)
- Mauro Cives
- Department of Biomedical Sciences and Human Oncology, Section of Internal Medicine and Clinical Oncology, University of Bari “Aldo Moro”, Bari, Italy
| | - Valeria Simone
- Department of Biomedical Sciences and Human Oncology, Section of Internal Medicine and Clinical Oncology, University of Bari “Aldo Moro”, Bari, Italy
| | - Francesca Maria Rizzo
- Department of Biomedical Sciences and Human Oncology, Section of Internal Medicine and Clinical Oncology, University of Bari “Aldo Moro”, Bari, Italy
| | - Franco Silvestris
- Department of Biomedical Sciences and Human Oncology, Section of Internal Medicine and Clinical Oncology, University of Bari “Aldo Moro”, Bari, Italy
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Verrotti A, Basciani F, De Simone M, Trotta D, Morgese G, Chiarelli F. Insulin resistance in epileptic girls who gain weight after therapy with valproic acid. J Child Neurol 2002; 17:265-8. [PMID: 12088081 DOI: 10.1177/088307380201700405] [Citation(s) in RCA: 63] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Valproic acid is effective for treatment of many types of epilepsy, but its use in epileptic patients can be associated with an increase in body weight that could interfere with treatment compliance. The weight gain may result from different mechanisms, but the exact pathogenesis is still unknown. To evaluate insulin sensitivity in adolescents who gained weight during treatment with valproic acid, we studied 20 girls with different types of epilepsy: 15 patients had primary generalized seizures, including absence seizures (3 cases), and 5 patients had partial seizures. After 1 year of valproic acid treatment, the obese patients had serum insulin levels significantly higher than patients who did not gain weight (51.4 +/- 25.3 versus 28.2 +/- 12.9). Moreover, we observed that epileptic patients who gained weight were also insulin resistant in comparison with nonobese epileptic subjects. At the end of treatment, all patients showed normal levels of serum testosterone, androstenedione, dehydroepiandrosterone sulfate, follicle-stimulating hormone (FSH), and luteinizing hormone. We found no significant correlation between insulinemia and serum valproic acid concentrations in obese and nonobese patients treated with valproic acid. Our study demonstrates that basal hyperinsulinemia and insulin resistance can be present in patients who develop obesity during valproic acid treatment. Therefore, these obese patients could be exposed to the risks related to these metabolic abnormalities; if these data are confirmed in longer studies, these side effects may raise some concerns about the safety of valproic acid.
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Affiliation(s)
- Alberto Verrotti
- Department of Medicine, University of Chieti, Ospedale Policlinico, Italy.
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Abstract
Weight gain is a common side effect of valproate treatment. Several mechanisms have been suggested for its pathophysiology; of these, impairment of beta-oxidation of fatty acids and increased insulin secretion have been supported by clinical studies. To investigate whether changes in carnitine and insulin levels had a role in the weight gain occurring with valproate treatment in children, 20 patients with epilepsy were randomly assigned to receive either carnitine or placebo supplementation in addition to valproate. After a follow-up period of 3 months, weight gain was observed in both groups. The mean insulin concentration and insulin/glucose ratios increased. Weight gain did not correlate with carnitine levels. These results suggest that weight gain during valproate treatment is not related to a decrease in carnitine levels. However, an increase in insulin levels together with a decrease in glucose levels may cause weight gain, possibly by stimulating appetite.
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Affiliation(s)
- E Demir
- Department of Pediatric Neurology, Hacettepe University, Ankara, Turkey
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7
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Chappell KA, Markowitz JS, Jackson CW. Is valproate pharmacotherapy associated with polycystic ovaries? Ann Pharmacother 1999; 33:1211-6. [PMID: 10573322 DOI: 10.1345/aph.19096] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
OBJECTIVE To review and evaluate the published data associating the use of valproate with the development of polycystic ovaries. DATA SOURCES A computerized search of MEDLINE (1966-May 1999) and Current Contents was performed. Also, bibliographies were cross-referenced to yield additional pertinent publications. All articles written in English were considered for review. STUDY SELECTION AND DATA EXTRACTION All pertinent clinical studies and review articles associating valproate with polycystic ovaries and other endocrinologic disorders were evaluated. DATA SYNTHESIS Valproate is among the most commonly used medications today effective in the treatment of a variety of neurologic and psychiatric disorders. An accumulating body of literature has suggested an increase in the incidence of polycystic ovarian syndrome among women treated with valproate. The syndrome is characterized as hyperandrogenism and chronic anovulation in the absence of identifiable adrenal or pituitary pathology. It is a highly prevalent syndrome, affecting 2-22% of women in the general population. CONCLUSIONS Although a number of studies have found clear evidence of neuroendocrine perturbations in patients treated with valproate, there are presently limited data from large controlled studies involving valproate monotherapy. Nonetheless, there appears to be a greater incidence of polycystic ovaries associated with valproate use in comparison with other anticonvulsants. The mechanism by which valproate may induce polycystic ovarian syndrome is unknown, but could possibly be secondary to valproate-induced weight gain or direct interference with steroid metabolism. Further study of the potential association of valproate treatment with the development of polycystic ovarian syndrome is warranted. Until the issue is clarified, clinicians should at least be aware of the possibility of valproate-induced polycystic ovarian syndrome and monitor patients accordingly.
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Isojärvi JI, Laatikainen TJ, Knip M, Pakarinen AJ, Juntunen KT, Myllylä VV. Obesity and endocrine disorders in women taking valproate for epilepsy. Ann Neurol 1996; 39:579-84. [PMID: 8619542 DOI: 10.1002/ana.410390506] [Citation(s) in RCA: 240] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
We recently reported the frequent occurrence of polycystic ovaries and hyperandrogenism in women taking valproate for epilepsy, especially when the medication was started before the age of 20 years. In the present study we evaluated the association of obesity and hyperinsulinemia with valproate-related polycystic ovaries and hyperandrogenism in women with epilepsy. Sixty-five women participated in the study. Twenty-two received valproate monotherapy and 43 received carbamazepine monotherapy. In addition to clinical examination, vaginal ultrasonography was performed to determine ovarian size, and the concentrations of serum sex hormones, insulin, insulin-like growth factor 1, and the insulin-like growth factor-binding proteins 1 and 3 (IGFBP-1 and IGFBP-3) were measured. Fifty-nine percent of the women on valproate were obese, and in a retrospective analysis an indisputable weight gain (mean, 21 kg; range, 8-49 kg) was found in 50% of the women taking valproate. Fourteen (64%) of the women on valproate had polycystic ovaries, hyperandrogenism, or both. These women were obese, and in addition to elevated serum androgen levels, they had high concentrations of fasting serum insulin and low levels of serum insulin-like growth factor-binding protein 1. Valproate therapy for epilepsy is associated with weight gain during treatment in approximately 50% of women patients. The weight gain can be progressive, and is associated with hyperinsulinemia and low serum levels of insulin-like growth factor-binding protein 1, which may lead to hyperandrogenism and polycystic ovaries.
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Affiliation(s)
- J I Isojärvi
- Department of Neurology, University of Oulu, Finland
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Okamoto T, Kusunoki M, Kusuhara K, Yamamura T, Utsunomiya J. Water and electrolyte balance after ileal J pouch-anal anastomosis in ulcerative colitis and familial adenomatous polyposis. Int J Colorectal Dis 1995; 10:33-8. [PMID: 7745321 DOI: 10.1007/bf00337584] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The water and electrolyte balance was studied in 31 patients with ulcerative colitis (UC) and 22 with familial adenomatous polyposis (FAP) who underwent staged surgery involving colectomy and ileal J pouch-anal anastomosis (IAA), preoperatively, after terminal ileostomy, after high ileostomy, and after ileostomy closure. Serum electrolytes did not differ between each surgical stage. After terminal or high ileostomy, daily urine volume and urinary sodium loss was significantly lower, and daily fecal weight and fecal sodium loss was significantly higher than preoperatively. After ileostomy closure, urinary and fecal sodium loss became closer to preoperative value. Daily urinary potassium loss was significantly higher and fecal loss was lower after terminal and high ileostomy than preoperatively and did not show a significant change after ileostomy closure. The urinary sodium to potassium ratio after ileostomy closure was lower than preoperatively, but was higher than that after terminal and high ileostomy. Plasma aldosterone and renin levels were only significantly increased after high ileostomy. These findings indicate that high or terminal ileostomy caused chronic dehydration, which was compensated for by activation of the renin-aldosterone axis, while the water and electrolyte balance became closer to normal after ileostomy closure following ileoanal anastomosis.
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Affiliation(s)
- T Okamoto
- Second Department of Surgery, Hyogo College of Medicine, Japan
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10
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Lado Abeal J, Rey Losada C, Cabezas Agricola JM, Cabezas-Cerrato J. Influence of sodium valproate on medium-late luteal phase pulsatile LH secretion in normal women. Clin Endocrinol (Oxf) 1994; 40:127-31. [PMID: 8306471 DOI: 10.1111/j.1365-2265.1994.tb02454.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
OBJECTIVE It is not known whether gamma-aminobutyric acid (GABA) is involved in control of pulsatile LH secretion in human beings. Previous work by our group has shown that manipulation of the GABAergic system with sodium valproate does not affect pulsatile LH secretion in normal women in the late follicular phase. However, it has been suggested that steroid levels are critical for the influence of GABA upon hormone secretion; in particular, progesterone has been said to enhance inhibition by GABA. In this work we studied the effect of sodium valproate on pulsatile LH secretion in medium-late luteal phase of normal women. DESIGN Six normal young women were studied over an 8-hour period in two successive menstrual cycles. On each occasion blood samples were taken every 10 minutes between 1000 and 1800 h. We administered 400 mg of sodium valproate every 8 hours on the 7 days preceding their second cycle and additional 400 mg at 0900 and 1400 h on the day of the study. Ovulation day was estimated by means of serial ovarian ultrasound examinations and confirmed by serum progesterone concentrations. MEASUREMENTS In each cycle, LH, oestradiol and progesterone were determined by radioimmunoassay and sodium valproate by repolarization fluorescence spectrophotometry. The series of LH levels was smoothed for 1-minute sampling periods by means of a spline function and analysed by means of a program developed in our laboratory and written in Fortran 77. The program deconvolved the signal and calculated the pulse area, pulse duration, interpulse interval and number of pulses. LH pulse identification on the deconvolved signals was performed using our own method based on Friedman's non-parametric statistic. The statistical significance of differences between parameters was estimated using the Mann-Whitney test and Wilcoxon signed rank test. RESULTS There were no significant differences in LH pulse area, pulse duration, interpulse interval or number of pulses with the administration of sodium valproate. CONCLUSIONS Activation of the GABAergic system with sodium valproate had no biologically significant effect on the mid-late luteal phase pulsatile LH secretion in normal women.
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Affiliation(s)
- J Lado Abeal
- Cátedra de Patologia General (Departamento de Medicina), Hospital General de Galicia, Spain
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Vorum H, Gram L, Honoré B. Valproate and palmitate binding to serum albumin in valproate-treated patients. Relation to obesity. Epilepsy Res 1993; 16:55-64. [PMID: 8243440 DOI: 10.1016/0920-1211(93)90040-e] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Binding of valproate and palmitate to serum albumin was studied in 29 valproate-treated epileptic patients. The results were compared with similar observations in a reference group of 43 non valproate-treated individuals. The binding affinity for palmitate was decreased (P < 0.0001) resulting in increased availability of long-chain fatty acids (P = 0.008) due to competitive valproate binding in the valproate-treated patients. The findings support a hypothesis on the pathogenesis of obesity as a complication of valproate treatment of epilepsy.
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Affiliation(s)
- H Vorum
- Institute of Medical Biochemistry, University of Aarhus, Denmark
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12
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Kusuhara K, Kusunoki M, Okamoto T, Sakanoue Y, Utsunomiya J. Reduction of the effluent volume in high-output ileostomy patients by a somatostatin analogue, SMS 201-995. Int J Colorectal Dis 1992; 7:202-5. [PMID: 1293241 DOI: 10.1007/bf00341221] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Twelve ileostomy patients were given subcutaneous SMS 201-995 therapy (100 micrograms t.d.s. for 5 days) in a randomized placebo-controlled trial. All patients had ileostomies constructed 60 cm proximal to the terminal ileum (proximal ileostomy) following restorative proctocolectomy. SMS 201-995 reduced the daily ileostomy output from 997 +/- 52 g to 736 +/- 28 g, P < 0.05, along with a decrease in daily sodium and chloride excretion (sodium: 92.60 +/- 8.51 to 75.22 +/- 8.64 mEq, chloride: 143.46 +/- 8.54 to 113.60 +/- 15.84 mEq; both P < 0.05). There were no significant changes in the plasma levels of glucagon, C peptide, insulin, renin or aldosterone with SMS 201-995 therapy. Patients developed no severe side effects and reported easier management of the ileostomy and a reduction in thirst. Our results suggest a possible clinical role for SMS 201-995 in the management of proximal ileostomy.
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Affiliation(s)
- K Kusuhara
- Second Department of Surgery, Hyogo College of Medicine, Japan
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13
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Kusunoki M, Shoji Y, Sakanoue Y, Yanagi H, Fujita S, Yamamura T, Utsunomiya J. gamma-Aminobutyric acid enhances the tone of human internal anal sphincter. J Surg Res 1991; 51:293-6. [PMID: 1656145 DOI: 10.1016/0022-4804(91)90110-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The effect of gamma-aminobutyric acid (GABA) on the human internal anal sphincter was investigated. Cumulative applications of GABA produced concentration-dependent contractions (10(-8)-10(-5) M) of the isolated human sphincter. Pretreatment with bicuculline (GABAA antagonist) turned them to relaxation. Muscimol, a GABAA agonist, induced concentration-dependent contractions (10(-8)-10(-5) M); however, baclofen (GABAB agonist, 10(-8)-10(-5) M) promoted concentration-dependent relaxation of the strips. These results suggested that both excitatory GABAA receptors and inhibitory GABAB receptors exist in the internal anal sphincter. Oral administration of sodium valproate (1600 mg/day), a GABA transaminase inhibitor, enhanced the anal canal resting pressure in 10 normal volunteers. Anal manometry showed a significant elevation in tonus without affecting amplitudes or frequencies. These results indicated that endogenous GABA, which was increased by sodium valproate, produced elevations in the anal canal resting pressure through its specific receptors in the human internal anal sphincter.
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Affiliation(s)
- M Kusunoki
- Second Department of Surgery, Hyogo College of Medicine, Japan
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Gilon P, Mallefet J, De Vriendt C, Pauwels S, Geffard M, Campistron G, Remacle C. Immunocytochemical and autoradiographic studies of the endocrine cells interacting with GABA in the rat stomach. HISTOCHEMISTRY 1990; 93:645-54. [PMID: 1970340 DOI: 10.1007/bf00272208] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
There are now increasing evidences suggesting that GABA is able of direct interaction with certain endocrine cells. In the present study, highly specific anti-GABA-glutaraldehyde antibodies and 3H-GABA uptake were used at the light and electron microscope levels to investigate the occurrence of cells containing endogenous GABA or taking up exogenous GABA in the mucosal antrum and corpus of the rat stomach. Only certain endocrine cell types of both regions were immunostained or grain-labelled. However, the morphology of their secretory granules did not allow to identify the nature of their hormone with certainty but suggested that somatostatin-like cells could interact with GABA. The combination of gastrin and somatostatin immunodetection with 3H-GABA uptake autoradiography at the light microscope level, revealed that a subpopulation of somatostatin-like cells and other still unidentified endocrine cells are able to take up GABA, while the gastrin-like cells are not. These results reinforce the hypothesis that certain endocrine cell types of the diffuse endocrine system of the digestive tract are able to directly interact with GABA.
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Affiliation(s)
- P Gilon
- Laboratoire de Biologie Cellulaire, Université Catholique de Louvain, Belgium
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