摘要:

AbstractPain processing in the trigeminal complex has been thought to reside primarily in the spinal subnucleus caudalis (Vc). However, trigeminal tractotomies eliminating primary afferent input to Vc and severance of secondary trigemino‐thalamic fibers from Vc do not disturb pain perception from the central face and oral cavity. Furthermore, large numbers of neurons that are highly responsive to noxious stimuli and suppressed by inputs from the periaqueductal gray and raphe complex have been identified in subnuclei interpolaris (Vi) and oralis (Vo). Therefore, the purpose of this study was to assess the distribution and spatial arrangements of nociceptive modulatory transmitters with nociceptive afferents and trigemino‐thalamic relay cells in the rostral portion of the spinal trigeminal nuclear complex.The dental pulp contains predominantly nociceptors that project to all three subdivisions of the trigeminal spinal complex. These projections were visualized by anterograde transganglionic transport of horseradish peroxidase or by degeneration following administration of toxic ricin to the pulp chambers. The spatial arrangements of dental primary afferents with enkephalinergic (ENK) and serotoninergic (5HT) inputs was then assessed by employing avidin‐biotin peroxidase and protein‐A colloidal gold double‐labeling immunocytochemistry. Trigemino‐thalamic relay cells were also labeled by retrograde transport of HRP after stereotaxic injections into the ventrobasal thalamus. ENK and 5HT immunoreactivity was found in the ventrolateral quadrant and lateral margin of Vi, together with the adjacent interstitial nucleus (IN). This activity extended from the caudal pole of Vi and the periobex region, where it was most dense, rostrally to a position approximately 2.9 mm from the Obex. Neither ENK nor 5HT immunoreactivity was observed in Vo. Primary dental afferents projected into the ventromedial quadrant of rostral Vi and were found in the ventrolateral quadrant and dorsal aspect of the subnucleus farther caudally. They appeared as simple boutons with single contacts or as larger, sometimes scalloped terminals that formed multiple contacts. Postsynaptic elements were usually small dendritic profiles, although relay cell somata rarely received primary afferent inputs. Many primary afferents entered areas of synaptic clustering and contacted enkephalinergic dendrites, some of which were also postsynaptic to serotoninergic synapses. Alternatively, primary afferents contacted unlabeled processes that were also postsynaptic to the enkephalinergic element to form a triad arrangement. The least common occurrence was axo‐axonic contacts in which enkephalinergic synapses were presynaptic to primary afferents. Both enkephalinergic and serotoninergic synaptic categories displayed round vesicles and generally formed asymmetric junctions. The most complex junctional arrangements were found in the lateral marginal area of Vi. This study shows that the Vi has relatively circumscribed areas that contain nociceptive modulatory transmitters important in pain processing. These occur in synaptic complexes displaying spatial arrangements comparable to those previously described for the spinal and medullary dorsal horns (Basbaum and

ISSN:0887-4476    

DOI:10.1002/syn.890040303

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1989

数据来源: WILEY

摘要:

AbstractCorticotropin‐releasing factor (CRF) is the major physiological regulator of the hypothalamic‐pituitary‐adrenal (HPA) axis. However, considerable evidence indicates that CRF may be responsible for integrating not only the endocrine, but the autonomic and behavioral responses of an organism to stress as well. In addition, clinical studies indicate that CRF of both hypothalamic and extrahypothalamic origin may be hypersecreted in major depression as well as other psychiatric disorders.These findings, taken together, led to the hypothesis that the efficacy of antidepressant and/or anxiolytic drugs may be related to their actions on CRF‐containing neural pathways in the central nervous system (CNS). Therefore, alterations of CRF concentrations in 18 rat brain regions were studied after acute administration of a tricyclic antidepressant (imipramine) or one of two triazolobenzodiazepines (alprazolam or adinazolam) that possess anxiolytic properties typical of benzodiazepines, as well as purported antidepressant activity unique to these compounds.Treatment with alprazolam or adinazolam increased hypothalamic CRF concentrations, which was associated with lower plasma ACTH concentrations. In contrast, the concentration of CRF was markedly reduced in the locus coeruleus, amygdala, and several cortical regions by either triazalobenzodiazepine. Acute treatment with imipramine was without effect on CRF concentrations in any brain region studied.Of particular interest is the finding that the two triazolobenzodiazepines exert effects on CRF concentrations in the locus coeruleus and hypothalamus that are opposite to CRF changes seen after

ISSN:0887-4476    

DOI:10.1002/syn.890040304

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1989

数据来源: WILEY

摘要:

AbstractIn order to determine if post‐mortem delays could account for the apparent absence of 5‐HT1Bsites reported in human brain, 5‐HT1Bbinding parameters were determined in fresh and fresh‐frozen cortical biopsies and compared to results obtained in post‐mortem tissues. Binding parameters and in vitro receptor autoradiography were performed by using two different ligands which have been shown to label 5‐HT1Bsites, namely [3H]5‐HT, in presence of 100 nM 8‐OH‐DPAT, and [125I]cyanopindolol, in presence of 10 μM (–)isoproterenol. No specific binding was detected with [125I] cyanopindolol in either fresh cortical biopsies or post‐mortem tissues, suggesting that the apparent absence of 5‐HT1Breceptor sites reported earlier was not related to long post‐mortem delays. Some specific labelling was seen with [3H]5‐HT, in presence of 8‐OH‐DPAT. This binding, which is unlikely to be to the 5‐HT1Btype, could represent labelling to the 5‐HT1Dor 5‐HT1Esites (Herrick‐Davis and Titeler:J. Neurochem., 50:1624–1631, 1988; Peroutka:Trends Neurosci., 11:496–500, 1988; Titeler and Herrick‐Davis:Soc. Neurosci. Abst., 14:553, 1988;

ISSN:0887-4476    

DOI:10.1002/syn.890040305

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1989

数据来源: WILEY

摘要:

AbstractMorphological parameters were compared for dendritic spines of spiny stellate neurons in layer IV of the barrel region of mouse somatosensory cortex, which synapse with degenerated thalamocortical afferents (TC spines) and with intact, unidentified axon terminals (UI spines). Spiny stellate neurons were labeled for light and electron microscopic identification by Golgi impregnation and gold toning. Dendritic spines were examined in series of thin sections, and TC spines were ultrastructurally detectable because of the degeneration‐induced characteristic appearance of the TC axon terminals. Results show that the means of the width of the spine head and of the length of the spine stalk were significantly higher in TC spines than in UI spines by about 11 and 25%, respectively. The variability of these two morphological parameters was significantly lower for TC spines. The mean of the spine stalk width at the narrowest cross section of the stalk was about 0.12 μm, with no significant difference observed between the two spine groups. No specific relationship was found in either the TC or the UI groups of spines between the length of the spine stalk and the width of the spine stalk at its narrowest profile.As structural features typifying transneuronal degeneration were not observed along the dendritic spines examined, it is speculated that the morphological differences encountered between the TC and UI spines may result, at least in part, from the degeneration‐induced synaptic inactivity of the TC axospinous synapses, rather than exclusively from any direct effects of the degeneration pro

ISSN:0887-4476    

DOI:10.1002/syn.890040306

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1989

数据来源: WILEY

摘要:

AbstractConcentrations of preprosomatostatin‐mRNA and preprocholecystokinin‐mRNA were determined by Northern blot analysis in rats 2, 10, and 30 days after strong seizures induced by a single intraperitoneal injection of kainic acid. At all time intervals examined, levels of preprosomatostatin‐mRNA were increased in the frontal cortex; so were levels of preprosomatostatin‐mRNA in the striatum. Transient increases, i.e., 2 days after kainic acid, of preprocholecystokinin‐mRNA were observed in the frontal cortex and the substantia nigra. Preprocholecystokinin‐mRNA was reduced in the hippocampus 2 and 10 days after kainic acid. Both preprosomatostatin‐ and preprocholecystokinin‐mRNA levels showed a tendency to be reduced in the amygdala/pyriform cortex at all three time intervals.The increases in mRNA levels suggest enhanced rates of synthesis of the respective neuropeptides subsequent to kainic acid‐induced seizures. They may also reflect a prolonged increase in the activity of the respective peptide‐containing neurons. This is of special interest in the frontal cortex, since in this area both neuropeptides are found in interneurons and are widely colocalized with

ISSN:0887-4476    

DOI:10.1002/syn.890040307

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1989

数据来源: WILEY

摘要:

AbstractEvidence from experiments performed in turtle and fish retina suggests that dopamine (DA) modulates the permeability of gap junctions. The present experiment was aimed at determining if DA has a similar role in the mammalian neostriatum. Adults rats received one of four treatments: Unilateral electrolytic substantia nigra lesions, unilateral injection of 6‐hydroxydopamine (6‐OHDA) into the substantia nigra, unilateral neocortical aspiration, or no treatment. After 3–5 weeks, neostriata from both sides of the brain were prepared for in vitro intracellular recordings. Recorded neurons (N α 150) were filled with Lucifer Yellow (LY), a low molecular weight dye that crosses gap junctions. In animals with electrolytic nigral lesions, dye‐coupling in the ipsilateral neostriatum occurred after 38% of the intracellular injections. After 6‐OHDA lesions, 19% of the injections produced dye‐coupling in the ipsilateral neostriatum. This difference may have been accounted for by the fact that electrolytic lesions produced a greater degree of DA loss than 6‐OHDA injections. Both of these percentages contrast with the very small percentage of dye‐coupling found in intact animals or in animals with neocortical lesions. Dye‐coupling occurred only between medium‐sized spiny cells. No morphological differences between dye‐coupled and non‐dye‐coupled cells were observed with light microscopy. Overall, passive and active electrophysiological properties of dye‐coupled and single neurons were similar. The results suggest that DA may function in the neostriatum to control p

ISSN:0887-4476    

DOI:10.1002/syn.890040308

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1989

数据来源: WILEY

摘要:

AbstractPhysiological and morphological evidence for coupling between neostriatal neurons was obtained from the developing rat. Intracellular injections of Lucifer Yellow‐CH (LY) were made in rat neostriatal slices to study dye transfer (coupling) between neurons. The incidence of interneuronal coupling was 70% in early postnatal (P) periods and declined gradually to 10% in the adult. The number of neurons filled by a single intracellular injection also declined with age. LY injection into single neurons commonly marked aggregates of 4 to 6 cells in neonates. Single injections never produced more than one coupled pair in P20 or older rats. Neurons in which fast prepotentials (FPPs) could be evoked were consistently found to be dye‐coupled. FPPs were resistant to collision with action potentials generated by intracellular current injection. When chemical synaptic transmission was blocked by Mn2+, short‐latency depolarization (SLDs) could be evoked by extracellular stimulation. The SLDs were distinguished from chemical synaptic potentials by their “all or none” nature and by their insensitivity to changes in membrane potential. No SLDs were observed in adult neurons. FPPs and SLDs may be indicators of electrotonic transmission between coupled cells. The high incidence of coupling early in development might reflect intercellular communication that contributes to the differentiation and growth of neostriata

ISSN:0887-4476    

DOI:10.1002/syn.890040309

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1989

数据来源: WILEY

摘要:

AbstractRecent findings have demonstrated the existence of dopaminergic (DA) markers in the nbM of the human brain and a reduction of these markers in both the nbM and the striatum of patients suffering from Alzheimer's disease (AD). To investigate the source of the DA synaptic markers found in the nbM, rats received unilateral 6‐OHDA lesions of the substantia nigra pars compacta (SNc). The SNc lesions caused signigificant reductions in DA and DOPAC but not HVA in the nbM and the striaum;3H‐sulpiride binding to D2receptors ipsilateral to the SNc lesion was significantly increased in the stratum (16%), consistent with denervation supersensitivity, but single‐point analysis showed no significant changes in the nbM. These data suggest that the decreases in DA and3H‐spiperone binding levels observed in the nbM of AD patients may be due to partial destruction of DA nbM afferent projections from the br

ISSN:0887-4476    

DOI:10.1002/syn.890040310

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1989

数据来源: WILEY

摘要:

Abstract(+)‐Pentazocine, a potent sigma ligand that lacks affinity for PCP receptors, produced dose‐dependent contralateral circling behavior following microinjections in the substantia nigra of rats. This effect was attenuated by 6‐hydroxydopamine (6‐OHDA) lesions of ascending dopamine neurons and enhanced by systemic injections of amphetamine. 6‐OHDA lesions also attenuated the circling produced by another selective sigma ligand, 1,3‐di‐o‐tolylguanidine (DTG). These findings suggest that sigma receptors are involved in the neural control of movement and the regulation of the ascending dopamine system. Since all typical antipsychotic drugs tested bind to sigma receptors with Ki values less than 1 μM, these findings further suggest that sigma receptors may mediate some of the motor side effects of antipsycho

ISSN:0887-4476    

DOI:10.1002/syn.890040311

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1989

数据来源: WILEY

摘要:

AbstractThe ontogeny of oxytocin receptors in rat forebrain was studied using the selective oxytocin receptor antagonist125I‐d(CH2)5[Try(Me)2, THR4, Tyr‐NH29]OVT ([125I]‐OTA). With in vitro receptor autoradiography, binding was noted on the first postnatal day in dorsal subiculum and thalamus. On postnatal days 5–18, intense labeling was evident in posterior cingulate cortex, dorsal subiculum, lateral septum and the CA1 subfield of hippocampus. Of these regions only the lateral septum expressed oxytocin receptors in adult brain. Competition studies on coronal sections through posterior cinguulate, septum, and dorsal subiculum at P10 demonstrated that transient binding sites in these areas were indeed oxytocin selective (OXY>AVP>V1V2). Results of saturation studies on cingulate membranes from 10‐day‐old pups agreed favorably with previous reports of the kinetics of [125I]‐OTA binding to adult oxytocin receptors (Kd= 0.1 nM in P10 cingulate cortex vs. 0.07 nM for adult ventral subiculum). In contast to these evanescent developmental sites, oxytocin receptors in the bed nucleus of the stria terminalis and the ventromedial nucleus of the hypothalamus only appeared in adulthood, presumably in response to the surge of gonadal steroi

ISSN:0887-4476    

DOI:10.1002/syn.890040312

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1989

数据来源: WILEY