Biological signals and receptors最新文献

{"title":"Stimulation of HCO3- secretion across cystic fibrosis pancreatic duct cells by extracellular ATP.","authors":"C Y Cheung,&nbsp;X F Wang,&nbsp;H C Chan","doi":"10.1159/000014555","DOIUrl":"https://doi.org/10.1159/000014555","url":null,"abstract":"<p><p>Previous studies have demonstrated that extracellular ATP is able to activate Ca2+-dependent Cl- channels which may be important in circumventing the defective cAMP-dependent pancreatic ductal HCO3- secretion in cystic fibrosis (CF). The present study further investigated the effect of extracellular ATP on the stimulation of HCO3- secretion across CF pancreatic duct cells (CFPAC-1). Cells were grown in culture plate inserts which enabled the access of a pH microelectrode to the apical compartment. Changes in apical pH upon stimulation by extracellular ATP, as an indication of HCO3- secretion, were measured. ATP induced a rapid increase in apical pH, which reached a plateau with an averaged pH unit of 0.3 higher than that measured in unstimulated cells. The effect of ATP was concentration dependent. The ATP-induced change in pH could be blocked by apical addition of Cl- channel blockers, indicating that activation of apical Cl- channel is vital for HCO3- secretion by the pancreatic duct cells. Together with the previous finding, the present study suggests that HCO3- secretion may be stimulated in CF pancreatic duct cells by extracellular ATP via a cAMP-independent pathway.</p>","PeriodicalId":79565,"journal":{"name":"Biological signals and receptors","volume":"7 6","pages":"321-7"},"PeriodicalIF":0.0,"publicationDate":"1998-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1159/000014555","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"20781133","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Vasopressin induces dopamine release and cyclic AMP efflux from the brain of water-deprived rats: inhibitory effect of vasopressin V2 receptor-mediated phosphorylation.","authors":"M G Tyagi,&nbsp;R K Handa,&nbsp;P M Stephen,&nbsp;J S Bapna","doi":"10.1159/000014556","DOIUrl":"https://doi.org/10.1159/000014556","url":null,"abstract":"<p><p>The neurohypophyseal hormone vasopressin (AVP) is widely distributed throughout the central nervous system. It acts as an excitatory transmitter in the CNS and plays an important physiological role in water and electrolyte homeostasis. However, water deprivation has been shown to induce changes in the levels of monoamines, but there is little knowledge about the influence of AVP on monoamine levels after water deprivation. In this study, we investigated the effect of AVP and its receptor antagonists on alterations in dopamine (DA) release and cyclic adenosine 3',5' monophosphate (cAMP) efflux from rat brain slices following water deprivation. Striatal brain slices (500 microm thick) were incubated in a medium with or without AVP (0. 1-1.0 microM) for 30 min. After 2 h of washout in normal medium, high KCl (40 mM)-evoked DA release and cAMP efflux from the rat brain slices were examined. In the brain slices of euhydrated animals, treatment with AVP slightly altered DA release and cAMP efflux from the brain. This increase in DA release and cAMP efflux was not significantly affected by the addition of a calcium/calmodulin-dependent protein phosphatase, calcineurin (20 microM), to the incubation medium or either by a V1 or V2 AVP receptor antagonist. In contrast, AVP significantly increased the DA release and enhanced the cAMP efflux from the brain slices of water-deprived animals. The AVP-induced increase of brain response in the water-deprived animals was significantly attenuated by a V2 receptor antagonist, partially by calcineurin, but not by a V1 receptor antagonist. The present results suggest that AVP may play a role in water-deprivation-induced DA release and cAMP efflux, which is possibly mediated through the activation of the V2 receptor. The V2 receptor action is attenuated by calcium/calmodulin-dependent dephosphorlyation of some cellular proteins critical for signal transduction.</p>","PeriodicalId":79565,"journal":{"name":"Biological signals and receptors","volume":"7 6","pages":"328-36"},"PeriodicalIF":0.0,"publicationDate":"1998-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1159/000014556","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"20781869","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Chronic exposure to hypergravity affects thyrotropin-releasing hormone levels in rat brainstem and cerebellum.","authors":"N G Daunton,&nbsp;F Tang,&nbsp;M L Corcoran,&nbsp;R A Fox,&nbsp;S Y Man","doi":"10.1159/000014557","DOIUrl":"https://doi.org/10.1159/000014557","url":null,"abstract":"In studies to determine the neurochemical mechanisms underlying adaptation to altered gravity we have investigated changes in neuropeptide levels in brainstem, cerebellum, hypothalamus, striatum, hippocampus, and cerebral cortex by radioimmunoassay. Fourteen days of hypergravity (hyperG) exposure resulted in significant increases in thyrotropin-releasing hormone (TRH) content of brainstem and cerebellum, but no changes in levels of other neuropeptides (β-endorphin, cholecystokinin, met-enkephalin, somatostatin, and substance P) examined in these areas were found, nor were TRH levels significantly changed in any other brain regions investigated. The increase in TRH in brainstem and cerebellum was not seen in animals exposed only to the rotational component of centrifugation, suggesting that this increase was elicited by the alteration in the gravitational environment. The only other neuropeptide affected by chronic hyperG exposure was met-enkephalin, which was significantly decreased in the cerebral cortex. However, this alteration in met-enkephalin was found in both hyperG and rotation control animals and thus may be due to the rotational rather than the hyperG component of centrifugation. Thus it does not appear as if there is a generalized neuropeptide response to chronic hyperG following 2 weeks of exposure. Rather, there is an increase only of TRH and that occurs only in areas of the brain known to be heavily involved with vestibular inputs and motor control (both voluntary and autonomic). These results suggest that TRH may play a role in adaptation to altered gravity as it does in adaptation to altered vestibular input following labyrinthectomy, and in cerebellar and vestibular control of locomotion, as seen in studies of ataxia.","PeriodicalId":79565,"journal":{"name":"Biological signals and receptors","volume":"7 6","pages":"337-44"},"PeriodicalIF":0.0,"publicationDate":"1998-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1159/000014557","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"20781870","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Photomodulation of the melanocyte cell cycle by indoleamines.","authors":"B Iyengar","doi":"10.1159/000014558","DOIUrl":"https://doi.org/10.1159/000014558","url":null,"abstract":"<p><p>Melanocytes are photoresponsive cells which respond to varying doses of UV exposure in the G2 phase of the cell cycle by prominent dendricity. This photoresponse is related to indoleamine light sensitivity. The present study highlights the role of indoleamines in the photomodulation of the melanocyte cell cycle. The study was conducted on 40 whole-skin organ cultures taken from the marginal zone of vitiligo. Twenty organ cultures were subjected to G2-phase arrest, while 20 were incubated in tryptamine. The organ cultures were incubated in the dark, exposed to a pulse of 120 s UV at 2 h of incubation and harvested 3 and 6 h after UV exposure. It has been reported that the photosensitive enzymes N-acetyl transferase (NAT) and hydroxyindole-o-methyl transferase (HIOMT) are activated during the G2 phase. The conversion of serotonin to melatonin is inhibited by UV exposure as seen at 3 h. This activity recovers on continued dark incubation 6 h after UV exposure. On incubation with tryptamine, UV exposure results in utilisation of tryptamine as seen by prominent indoleamine positivity. Three hours after UV exposure, there is 75% dendricity indicating G2 phase traverse. There is a corresponding high serotonin positivity with a low melatonin positivity. This is reversed following 6 h of dark incubation with high melatonin positivity indicating reactivation of NAT and HIOMT. This is accompanied by a doubling of the melanocyte number due to mitotic traverse and an arrest in G1 phase with low utilisation of tryptamine. Thus tryptamine is utilised by melanocytes on UV exposure to be synchronised and traversed into G2 phase activating the photosensitive enzymes NAT and HIOMT. When followed by a dark phase, melatonin accumulates to traverse the melanocytes through M-phase of the cell cycle with doubling of the cell number. Thus the uptake and metabolisation of indoleamine precursors photomodulate the melanocyte cell cycle on UV exposure.</p>","PeriodicalId":79565,"journal":{"name":"Biological signals and receptors","volume":"7 6","pages":"345-50"},"PeriodicalIF":0.0,"publicationDate":"1998-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1159/000014558","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"20781137","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Modulations of early and late secretory processes by activation of protein kinases in the rat adrenal medulla.","authors":"A Warashina","doi":"10.1159/000014554","DOIUrl":"https://doi.org/10.1159/000014554","url":null,"abstract":"Modulatory effects of the activation of either protein kinase C (PKC) by phorbol 12,13-dibutyrate (PDBu) or protein kinase A (PKA) by forskolin on stimulant-evoked secretory processes in the perfused rat adrenal medulla were studied. PDBu or forskolin was applied during repetitive stimulation (30 s each at 10-min intervals) with nicotine, bradykinin, muscarine or histamine, and changes in [Ca2+]i (fura-2 microfluorometry) and catecholamine secretions (electrochemical detection) were simultaneously measured. PDBu markedly potentiated the nicotine-evoked secretion without altering the [Ca2+]i response. PDBu partially inhibited the muscarine-evoked secretion and almost completely blocked the histamine-evoked secretion, concomitantly with extensive suppressions of the [Ca2+]i responses to these stimulants. The bradykinin-evoked secretion was enhanced by PDBu despite a slight attenuation of the [Ca2+]i response. PDBu reduced bradykinin-induced intracellular Ca2+ release in a Ca2+-free medium but enhanced the secretion associated with the released Ca2+. These results suggest that PDBu-activated PKC modulates secretory processes at, at least, two different stages. An early-stage modulation may downregulate receptor/G protein systems, which accounts for the inhibitory effect of PDBu on the muscarine- and histamine-evoked responses. A late-stage modulation may generally promote Ca2+-triggered exocytosis after elevation of [Ca2+]i, which explains the potentiation of the nicotine-evoked secretion by PDBu. The late-stage modulation may counteract the early-stage modulation in bradykinin-stimulated cells. Forskolin potentiated the secretory responses to the four secretagogues without increasing the [Ca2+]i responses. PKA may modulate secretory process at a step(s) distal to the rise in [Ca2+]i as is the case with the late-stage modulation by PKC.","PeriodicalId":79565,"journal":{"name":"Biological signals and receptors","volume":"7 6","pages":"307-20"},"PeriodicalIF":0.0,"publicationDate":"1998-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1159/000014554","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"20781867","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Annual Physiology Symposium. Hong Kong, China, April 24-25, 1998. Tainan, Taiwan, October 17-19, 1997. Abstracts.","authors":"","doi":"10.1159/000014551","DOIUrl":"https://doi.org/10.1159/000014551","url":null,"abstract":"pp. 253–285 of this journal issue contains abstracts of the Annual Physiology Symposium 1998","PeriodicalId":79565,"journal":{"name":"Biological signals and receptors","volume":"7 5","pages":"253-306"},"PeriodicalIF":0.0,"publicationDate":"1998-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1159/000014551","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"20898698","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Annual physiology symposium1997. tainan, taiwan, october 17-19, 1997","authors":"","doi":"10.1159/000014552","DOIUrl":"https://doi.org/10.1159/000014552","url":null,"abstract":"pp. 286–304 of this journal issue contains abstracts of the Annual Physiology Symposium 1997","PeriodicalId":79565,"journal":{"name":"Biological signals and receptors","volume":"7 5","pages":"286-304"},"PeriodicalIF":0.0,"publicationDate":"1998-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1159/000014552","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"20684847","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effects of amphetamine and phenylethylamine on catecholamine release in the glomerular layer of the rat olfactory bulb.","authors":"A Mesfioui,&nbsp;F Math,&nbsp;K Jmari,&nbsp;A El Hessni,&nbsp;M K Choulli,&nbsp;J L Davrainville","doi":"10.1159/000014548","DOIUrl":"https://doi.org/10.1159/000014548","url":null,"abstract":"<p><p>In the present work, we have shown electrochemically that in the rat olfactory bulb (OB), extracellular dopamine (DA) was highest in the glomerular layer (GL), whereas extracellular noradrenaline (NA) appeared to be more uniformly distributed across layers. The GL catecholamine (CA) responses to amphetamine (AMPH) and phenylethylamine (PEA) were also characterized electrochemically using an in vivo model. Results of this investigation show that at a lower dose (1 mg/kg), PEA had no effect on CA release. In contrast, at a higher dose (10 mg/kg), it produced similar increases in either extracellular DA (17.5 +/- 7%) or extracellular NA (14 +/- 3%), and DA exhibited dose-independent increases to AMPH (93 +/- 8%: 1 mg/kg vs. 97 +/- 6%: 10 mg/kg) whereas NA exhibited dose-dependent increases to AMPH (24.5 +/- 6%: 1 mg/kg vs. 39 +/- 7%: 10 mg/kg). These data indicate that (i) PEA may increase CA release but less efficiently than AMPH. (ii) AMPH is more efficient on the DAergic than on the NAergic system since AMPH-induced DA release exceeded 2-4 times the AMPH-induced NA release.</p>","PeriodicalId":79565,"journal":{"name":"Biological signals and receptors","volume":"7 4","pages":"235-43"},"PeriodicalIF":0.0,"publicationDate":"1998-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1159/000014548","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"20644771","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Prospects of the clinical utilization of melatonin.","authors":"G A Bubenik,&nbsp;D E Blask,&nbsp;G M Brown,&nbsp;G J Maestroni,&nbsp;S F Pang,&nbsp;R J Reiter,&nbsp;M Viswanathan,&nbsp;N Zisapel","doi":"10.1159/000014545","DOIUrl":"https://doi.org/10.1159/000014545","url":null,"abstract":"<p><p>This review summarizes the present knowledge on melatonin in several areas on physiology and discusses various prospects of its clinical utilization. Ever increasing evidence indicates that melatonin has an immuno-hematopoietic role. In animal studies, melatonin provided protection against gram-negative septic shock, prevented stress-induced immunodepression, and restored immune function after a hemorrhagic shock. In human studies, melatonin amplified the antitumoral activity of interleukin-2. Melatonin has been proven as a powerful cytostatic drug in vitro as well as in vivo. In the human clinical field, melatonin appears to be a promising agent either as a diagnostic or prognostic marker of neoplastic diseases or as a compound used either alone or in combination with the standard cancer treatment. Utilization of melatonin for treatment of rhythm disorders, such as those manifested in jet lag, shift work or blindness, is one of the oldest and the most successful clinical application of this chemical. Low doses of melatonin applied in controlled-release preparation were very effective in improving the sleep latency, increasing the sleep efficiency and rising sleep quality scores in elderly, melatonin-deficient insomniacs. In the cardiovascular system, melatonin seems to regulate the tone of cerebral arteries; melatonin receptors in vascular beds appear to participate in the regulation of body temperature. Heat loss may be the principal mechanism in the initiation of sleepiness caused by melatonin. The role of melatonin in the development of migraine headaches is at present uncertain but more research could result in new ways of treatment. Melatonin is the major messenger of light-dependent periodicity, implicated in the seasonal reproduction of animals and pubertal development in humans. Multiple receptor sites detected in brain and gonadal tissues of birds and mammals of both sexes indicate that melatonin exerts a direct effect on the vertebrate reproductive organs. In a clinical study, melatonin has been used successfully as an effective female contraceptive with little side effects. Melatonin is one of the most powerful scavengers of free radicals. Because it easily penetrates the blood-brain barrier, this antioxidant may, in the future, be used for the treatment of Alzheimer's and Parkinson's diseases, stroke, nitric oxide, neurotoxicity and hyperbaric oxygen exposure. In the digestive tract, melatonin reduced the incidence and severity of gastric ulcers and prevented severe symptoms of colitis, such as mucosal lesions and diarrhea.</p>","PeriodicalId":79565,"journal":{"name":"Biological signals and receptors","volume":"7 4","pages":"195-219"},"PeriodicalIF":0.0,"publicationDate":"1998-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1159/000014545","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"20644767","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Adaptation-dependent differences in electroretinographic latency patterns in uniform and variegated horseshoe crabs.","authors":"B Kim,&nbsp;G S Wasserman","doi":"10.1159/000014547","DOIUrl":"https://doi.org/10.1159/000014547","url":null,"abstract":"<p><p>The carapaces of horseshoe crabs (Limulus polyphemus) differ. Some individuals have uniform carapaces and clear eyes while others have variegated carapaces and dark eyes. These differences have been reported to be correlated with latency differences in the electroretinogram (ERG) of the lateral eye. Such a result might have had a neural basis in the mechanisms underlying visual transduction but it could also have reflected a visual screening pigment difference. A direct experiment was therefore designed to choose between these two hypotheses by varying the relative state of adaptation. The results were as follows. In uniform animals, dark adaptation had the kind of effect seen in single photoreceptor cells - latencies were longer in dark-adapted eyes and latencies were also longer for dim flashes. However, variegated animals showed a significant adaptation interaction: in light adaptation, dimmer flashes produced the usual effect, namely a longer ERG latency, while in dark adaptation, latencies were close to equilatent, being within experimental error of each other for both flash energies. These data make it unlikely that the photoreceptor transduction mechanism is the locus of the visual differences between the two types of animals. Instead, they are consistent with an interaction of screening pigment effects with photoreceptor transduction effects.</p>","PeriodicalId":79565,"journal":{"name":"Biological signals and receptors","volume":"7 4","pages":"227-34"},"PeriodicalIF":0.0,"publicationDate":"1998-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1159/000014547","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"20644769","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}