摘要:

Some features of the morphofunctional organization of the CNS have been analysed.Different types of hierarchical organization have been recognized, each of which could deeply affect the circulation (communicational aspect) and elaboration (computational aspect) of information. These two aspects have been discussed on the basis of the existence of two types of electrochemical transmission in the CNS: wiring and volume transmission.By evaluating the CNS operations at different levels of analysis a ‘computational hierarchical organization’ has been delineated.This concept is very relevant to the understanding of the ‘computational power’ of the brain (Agnati&Fuxe 1984, Conrad 1985a).In fact, it leads to the distinction between horizontal and vertical elaboration of information.The hypothesis is introduced that in the vertical elaboration of information a central role may be played by the neuronal membrane. In fact, this structure can not only be influenced by the extra‐ and intracellular signals, but also effectively interconvert the electrical coding into the chemical coding of information. These aspects are discussed in the frame of the possible organization of the membrane into ‘domains’, each domain being a patch of membrane in which pre‐selected molecular movements are possible, resulting in molecular interactions. The movement of a molecule outside its domain is considered energetically unfavourable. The possible formal treatment of this hypothesis is mentioned in Conrad

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1989.tb08570.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

An extracellular recording method is described which permits in suitable model tissues (e. g.guinea‐pig or mouse vas deferens) study of the nerve impulse in sympathetic terminals and the release of transmitter from sites inside or outside the recording electrode. Negative‐ or positive‐going potentials were assumed to reflect the excitatory junction current (EJC) caused by transmitter released inside or outside the electrode, respectively, and hence termed ‘EJCi’ (ifor inside) or ‘EJCo’ (oforoutside).The EJCo were shown to be Ca2+‐dependent, blocked by addition of tetrodotoxin or guanethidine, resistant to theα1adrenoceptor blocking agent prazosin but suppressed by desensitization of P2‐purinoceptors byα,β‐methylene ATP, and hence, presumably, are caused by release of ATP as a sympathetic co‐transmitter. The amplitude of the EJCo was voltage‐dependent and increased with the length and frequency of stimulus trains within the range of 1–50 shocks at 0.1–2.5 Hz.In conclusion, combined use of EJCi and EJCo provides a useful tool for physiological and pharmacological analysis of pre‐ and post‐junctional events associated with the secretion of a sympathe

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1989.tb08571.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Extracellular recording in guinea‐pig or mouse vas deferens or rat tail artery was used to study the effects of some pharmacological agents on the nerve terminal spike (NTS) and the secretion of a sympathetic co‐transmitter (presumably ATP), as reflected in the excitatory junction current (EJC).A negative‐going EJCi (ifor inside) was assumed to reflect release from sites inside, and a positive‐going EJCo (oforoutside) release from sites outside the recording electrode. Passage into or out of the electrode seemed to be slow. Tetrodotoxin (TTX) in the outer medium blocked the NTS and ECJo as well as EJCi; TTX in the pipette blocked stimulus‐evoked but not spontaneous EJCi. The dihydropyridine Ca2+channel blocking agent, nifedipine, was without effect, but Cd2+in the external medium blocked EJCo and also, by an effect apparently ‘upstream’ of varicosities, inhibited EJCi (i. e.release within the patch) but not the NTS.When present in the outer medium theα2‐adrenoceptor agonists, clonidine and xylazine, blocked both EJCo and EJCi, but not the NTS.The effects of clonidine were blocked by yohimbine, which in itself increased the EJCo by about 50%.Neuropeptide Y and met‐enkephalin in the outer medium blocked EJCo; the effect of met‐enkephalin was blocked by naloxone. The K+channel blocking agents, tetraethylammonium and 4‐aminopyridine, inside or outside the electrode, increased dramatically the size of EJCi

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1989.tb08572.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Acute experiments were performed on anaesthetized rats using standard techniques of electrical stimulation and single‐unit recording in order to study the responses of the bed nucleus of the stria terminalis (BNST) neurons to homo‐ and contralateral stria terminalis (ST) inputs. Satisfactory records were obtained from 174 BNST neurons. The majority of these fired spontaneously at variable rates, with single random‐occurring spikes. The stria terminalis inputs are able to influence the discharges of many BNST neurons. Homolaterally the response patterns consisted of: (a) an excitatory–inhibitory sequence with variable latency in 61% of the cells; (b) a pure inhibitory period in 23% of the cells; (c) an inhibitory period followed by excitation in 2%; (d) no changes in 13% of the cells. The most frequent response to contralateral ST stimulation was excitation followed by inhibition (46%) and pure inhibition (28%).A high proportion of the cells (27%) did not show any change. These results correlate well with neuro‐anatomical studies of ST distribution on the BNST nucleus. Our finding of the high proportion of BNST cells affected in their discharge frequency by ST stimulation together with the variability of the observed responses is an indication of the close amygdala‐BNST relationship and also of the diverse functions in which both structures a

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1989.tb08573.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

In parotid, sublingual and submaxillary glands stimulated by continuous intravenous infusion of isoprenaline at various doses for 3 h, the concentrations of the polyamines putrescine, spermidine, spermine and N1‐acetylspermidine as well as the activities of ornithine decarboxylase and spermidine/spermine‐N'‐acetyltransferase were determined. Ornithine decarboxylase is the enzyme that catalyses the formation of putrescine from ornithine. The most striking effect was observed in parotid glands. Here, the β‐adrenergic agonist increased the activity of spermidine/spermine‐N1‐acetyltransferase markedly, but only slightly (if at all) that of ornithine decarboxylase. It also increased the concentrations of N1‐acetylspermidine and putrescine markedly. The result obtained in this gland indicates interconversion of higher polyamines

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1989.tb08574.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Polyamines are important for protein synthesis and tissue growth. In rat salivary glands, the activity of ornithine decarboxylase (ODC), the enzyme catalysing the formation of putrescine, and the content of putrescine, spermidine, spermine and N1‐acetylspermidine were assayed after parasympathetic or sympathetic nerve stimulation in the presence of various autonomic receptor blockers. Increases in ODC activity occurred on activation of non‐adrenergic and non‐cholinergic receptors in response to parasympathetic nerve stimulation and on activation of α(α1)‐ as well as of β(β1)‐adrenoceptors in response to sympathetic nerve stimulation. Moreover, in parotid glands, a β(β1)‐adrenoceptor‐mediated inverse pathway for putrescine formation seemed to exist: from spermidine via

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1989.tb08575.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Formation of inositol phosphates in response to carbachol, phenylephrine and vasoactive intestinal polypeptide (VIP) was studied after labelling with [3H]myo‐inositol in rat submandibular gland fragments. Carbachol enhanced the accumulation of inositol phosphates in a concentration‐dependent manner. This effect was independent of calcium in the incubation medium and totally antagonized by atropine (IC50= approx.1 nM).Phenylephrine also induced an increase in inositol phosphate accumulation, which was totally antagonized by prazosin but not by atropine. Vasoactive intestinal polypeptide, isoproterenol and forskolin, compounds known to enhance the levels of cAMP in rat salivary gland, or addition of dibutyryl‐cAMP (DB‐cAMP) failed to alter basal or carbachol‐evoked accumulation of inositol phosphates.It is concluded that the formation of inositol phosphates during muscarinic receptor stimulation with carbachol in rat submandibular gland fragments is not affected by adrenoceptor occupation or by cAMP.In particular, addition of VIP, which coexists with acetylcholine, did not alter the muscarinic inositol phosphate

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1989.tb08576.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Cholecystokinin (CCK) receptor antagonists may be valuable tools for investigating the physiological role of CCK in islet function. In this study, the effects of the three different CCK receptor antagonists, proglumide, CR 1409 and L‐364, 718, on basal and stimulated insulin and glucagon secretion were investigatedin vivoin the mouse. Each of the CCK antagonists was injected intravenously, either alone or together with one of the secretagogues CCK‐8 (5.3 nmol kg‐1), carbachol (0.16μmol kg‐1) or glucose (2.8 mmol kg‐1).At a low dose level, proglumide (28 μmol kg‐1) inhibited selectively CCK‐8‐induced insulin and glucagon secretion. However, at a higher dose level (280μmol kg‐1), proglumide inhibited also carbachol‐ and glucose‐induced insulin secretion. Furthermore, proglumide elevated basal plasma levels of both glucagon and glucose. CR 1409 inhibited CCK‐8‐induced insulin secretion at a high (21μmol kg‐1) but not at a low (0.21μmol kg‐1) dose level. In contrast, CCK‐8‐induced glucagon secretion was not affected by CR 1409.L‐364, 718 (2.4μmol kg‐1) inhibited both CCK‐8‐induced insulin and glucagon secretion. In contrast, L‐364, 718 did not affect basal plasma levels of insulin, glucagon or glucose or those levels after stimulation with carbachol or glucose. We conclude that, of these three CCK antagonists, L‐364,718 is the most specific CCK receptor antagonist for studies o

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1989.tb08577.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

During interdigestive periods, there is a resistance to flow in the biliary tract exerted by the sphincter of Oddi, resulting in a pressure gradient between the common bile duct and the duodenum. In this experimental study, this flow resistance was studied with both a constant‐flow and a constant‐perfusion technique in fasted, anaesthetized cats. The flow resistance exerted by the sphincter is higher when it is perfused by a constant flow compared to when the common bile duct pressure is kept constant and the flow varies in response to its muscular activity. It was demonstrated with each method that the flow resistance in the choledocho‐duodenal junction is reduced in response to distension of the biliary tree and gallbladder and also by distension of the duodenum. Cholecystokinin was shown to reduce the flow resistance in the choledocho‐duodenal junction as estimated with either

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1989.tb08578.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Experiments were performed on acutely vagotomized cats during chloralose anaesthesia. Gastric H‐and HCO‐3secretions were calculated from the pH and Pco2in a luminal perfusate. Gastric motility was reflected by changes in hydrostatic pressure within the luminal perfusion system (‘intragastric pressure’).Duodenal HCO‐3secretion was monitored by pH titrationin situ.Animals with an intact sympatho‐adrenal system (group 1) were compared with others subjected to splanchnicotomy (group 2), adrenal gland ligation (group 3), and splanchnicotomy plus adrenal gland ligation (group 4).Basal gastric H+secretion, as well as vagally induced H‐secretory responses, did not differ significantly between groups. Basal gastric HCO‐3secretion was lower in all groups with a manipulated sympatho‐adrenal system compared to the intact controls. Vagally induced increases in gastric HCO‐3secretion were enhanced in the splanchnicotomized groups (groups 2 and 4).Basal as well as vagally induced increases in intragastric pressure and duodenal HCO‐3secretion were enhanced in animals subjected to splanchnicotomy, with or without simultaneous adrenal gland ligation (groups 2 and 4).Adrenal gland ligationper sehad no such effects. The results suggest that the adrenal glands exert a stimulatory action on basal gastric HCO‐3secretion. Basal intragastric pressure and basal duodenal HCO‐3secretion are inhibited by post‐ganglionic sympathetic neurons, not involving the adrenal glands. Also, vagal excitatory effects on gastric motility, as well as on gastric and duodenal HCO‐3secretions, are inhibited by s

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1989.tb08579.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY