The effects of neurotensin, vasoactive intestinal polypeptide and other neuropeptides on the secretion of somatostatin from cerebral cortical cells

We have examined the effects of several neuropeptides on the release of immunoreactive somatostatin from cerebral cortical cells in vitro. Neurotensin and vasoactive intestinal polypeptide induced large increases in somatostatin release, whereas cholecystokinin, gonadotropin releasing hormone and Met-enkephalin induced only modest increases. Thyrotropin releasing hormone and insulin had no effect. These results demonstrate a complex interaction amongst neuropeptides in the cerebral cortex, which must be considered in future studies of the roles of peptides in cortical function.     

Topographical differences in the trigeminal sensitivity of the human nasal mucosa

The aim of the study was to investigate differences in the distribution of intranasal trigeminal receptors in humans using an electrophysiological measure of trigeminally induced activation, the negative mucosa potential. A total of 29 young, healthy volunteers participated, results were on the basis of data from 18 participants. The trigeminal irritant CO2 was presented using a computer-controlled olfactometer. Negative mucosa potential recording sites included the anterior olfactory cleft, the anterior septum, and the lower turbinate. Lowest amplitudes of the negative mucosa potential were found in the olfactory cleft, maximum amplitudes at the septum. Intranasal measurements of CO2 concentrations suggested that these differences were not due to the intranasal distribution of CO2. These results are compatible with the idea that the trigeminal system acts as a sentinel of the human airways.     

The effects of neuropeptides on discrete-trial conditioned avoidance responding

The effects of intracerebroventricular administration of several peptides on discrete-trial, conditioned avoidance responding were assessed in the rat. Three peptides (neurotensin, bombesin and beta-endorphin) produced a neuroleptic-like effect (i.e. a decrease in avoidance responding with no effect on escape responding). A low dose (0.6 nmol) of each peptide elicited a significant effect. Neurotensin and bombesin produced a significant but partial decrease in avoidance responding; larger doses of these peptides did not produce a greater effect. beta-Endorphin elicited dose-related decrements in avoidance responding. In addition, the effect of neurotensin, but not bombesin or beta-endorphin, was antagonized by simultaneous administration of an equimolar dose of thyrotropin-releasing hormone. Hence, the 3 peptides do not appear to produce decreases in avoidance responding by the same mechanism. Thyrotropin-releasing hormone, luteinizing hormone-releasing hormone, bradykinin, substance P, des-Tyr1-gamma-endorphin and melanotropin inhibiting factor did not significantly affect avoidance responding. These findings, taken together with previous findings, suggest that intracerebroventricular administration of certain endogenous peptides (neurotensin, bombesin and beta-endorphin) may exert neuroleptic-like effects.     

The effects of L-dopa on in vitro dopamine release from striatum

We have examined the effects of L-dihydroxyphenylalanine (L-DOPA) on endogenous dopamine (DA) and dihydroxyphenylacetic acid (DOPAC) efflux from superfused striatal slices prepared from adult male rats. Superfusion with L-DOPA (10 microM) caused a modest elevation in the tissue levels of DA and greatly increased the basal efflux and stimulation-evoked overflow of DA. Stimulation of slices under Ca2(+)-free conditions abolished DA overflow occurring in the absence of L-DOPA, but reduced DA overflow in the presence of L-DOPA by only 56%. Ca2(+)-independent DA release was not reduced by nomifensine. Destruction of DA terminals by pretreatment with 6-hydroxydopamine did not alter the capacity of L-DOPA to elevate tissue DA content. However, it attenuated the impact of L-DOPA on DA efflux, although this effect was somewhat smaller than was the apparent loss of DA terminals. These results suggest the following conclusions: (1) L-DOPA increases both the spontaneous and depolarization-induced release of DA; (2) some of the DA formed from L-DOPA can be released in response to depolarization by a process that does not involve either Ca2(+)-dependent exocytosis or reverse transport; and (3) most but not all of the DA efflux occurring in the presence of L-DOPA represents DA released from DA terminals. Furthermore, the observations suggest that the loss of DA terminals due to the progression of Parkinson's disease may be importantly involved in the gradual loss of clinical efficacy of the drug during chronic treatment.     

The bidirectional phase-shifting effects of melatonin on the arginine vasopressin secretion rhythm in rat suprachiasmatic nuclei in vitro

In vivo melatonin serves as a feedback signal to the circadian pacemaker located in the suprachiasmatic nuclei (SCN) and in vitro it phase advances the circadian rhythm of electrical activity in pacemaker cells. However, the occurrence and nature of phase shifting in secretion by cultured SCN neurons has not yet been established. Here we studied the effects of melatonin on the pattern of spontaneous arginine vasopressin (AVP) release in organotypic SCN slices. This culture mimicked the in vivo circadian AVP secretory rhythm, with low release during the subjective night and with peaks in secretion during the middle of subjective day. The endogenous period of the AVP secretory rhythm in organotypic culture ranged between 23 and 26 h, with the mean period of 24.1 +/- 0.3 h. Melatonin (10 nM) had variable effects on the pattern of AVP secretion depending on time of its application directly to the medium with organotypic SCN slices. When introduced at circadian time 22, 2 and 6 (the times corresponding to the late night and early day), melatonin delayed the AVP secretory rhythm by 1-4 h. When applied at circadian time 10 (late day), however, melatonin advanced the AVP secretory rhythm by about 2 h. At other circadian times, melatonin was ineffective. These results indicate that melatonin exhibits the bidirectional phase-shifting effects on circadian secretory rhythm clock, which depends on the time-window of its application.     

In vitro nerve-growth-promoting activity of human plasma alpha 1-acid glycoprotein

Human plasma alpha 1-acid glycoprotein or orosomucoid (OR), and its derivatives, prepared by sequential enzymatic cleavage of the carbohydrate units, were tested for their nerve-growth-promoting activities with explants of whole dorsal root ganglia from chick embryos. The results showed that the OR derivatives with terminal galactose, N-acetylglucosamine, or mannose have marked neurite-promoting activities. These preparations at a concentration of 100 micrograms/ml are equivalent to 5% fetal bovine serum (protein concentration 3,000 micrograms/ml) in their ability to elicit extensive neurite outgrowth and collateral branching. The asialo-OR, or ASOR, is the most potent form: its activity is estimated to be 20 times higher than that of transferrin and 100 times over that of fibronectin; it is approximately 1/1,500 that of NGF. The neurite-promoting activity of OR is independent of the non-neuronal cells and their products and can be blocked by a specific antiserum against OR. The mode of action of OR on the in vitro nerve growth is discussed and the pathophysiological significance of this plasma glycoprotein is considered in light of data from recent clinical and pathological studies.     

Neuropathy and anti-myelin-associated glycoprotein IgM M proteins: T cell regulation of M protein secretion in vitro

In patients with plasma cell dyscrasia, individual clones of antibody-producing cells proliferate abnormally and secrete monoclonal antibodies or M proteins in excess. The cause of the monoclonal proliferation of lymphocytes and M protein secretion is unknown and it is not known whether the M protein-secreting B cells are autonomous or capable of responding to regulatory T cells. We carried out experiments using lymphocytes from a patient with neuropathy and plasma cell dyscrasia whose IgM M protein bound to the myelin-associated glycoprotein (MAG) to determine whether secretion of the M protein in vitro was responsive to T cell help or suppression. M protein secretion was measured by an enzyme-linked immunosorbent assay system for measuring anti-MAG IgM, and the number of M protein-secreting lymphocytes was enumerated by a reverse hemolytic plaque assay specific for the M protein idiotype. The patient's B cells were maximally stimulated by pokeweed mitogen-activated autologous OKT4+ T-helper cells and the helper effect was inhibited by OKT8+ suppressor/cytotoxic T cells. Low levels of M protein secretion in the absence of T cells were also observed and there was partial stimulation of M protein secretion by T cells in the absence of pokeweed mitogen.     

Platelet membrane glycoprotein V: characterization of the thrombin-sensitive glycoprotein from human platelets

Human platelets contain a single membrane glycoprotein which is susceptible to thrombin proteolysis, glycoprotein V. We have purified 1 mg of glycoprotein V from 10(13) platelets using a combination of gel filtration, hydroxylapatite and ion-exchange chromatographies. Glycoprotein V has a blocked amino-terminus. Following proteolysis by human alpha-thrombin, a major fragment, termed glycoprotein Vf1, had the sequence Gly-Pro-Phe-X-Arg-Pro-Ala-Ala-Asp-Glu-Ser-Val-Glu-Ala-Pro-Val-Asn-Gln-Al a-Glu- Ala-Pro-. The purified glycoprotein was not a substrate for human gamma-thrombin. Glycoprotein V contained 17.5% carbohydrate, with the majority of the carbohydrate consisting of neutral hexoses. Deglycosylated glycoprotein V had a molecular weight of 57.5 kDa compared to the glycosylated protein's 82 kDa and the deglycosylated protein was recognized by polyclonal antibodies raised against glycoprotein V. Immunoelectrophoresis of human and rat platelets and megakaryocytes gave a single immunoreactive band, with the rat glycoprotein having a slightly larger molecular mass. Glycoprotein V is most likely an integral membrane protein.     

利培酮和氯氮平对体外培养大鼠胰岛分泌功能的影响

目的探讨利培酮与氯氮平对体外培养胰岛分泌功能的影响。方法 利用细胞培养技术,在不同的葡萄糖浓度(3.3 mmoL／L或16.7 mmol／L)和不同作用时间(1 h或4 h)下,以1 μmol／L利培酮或氯氮平分别作用于体外培养大鼠胰岛,用放射免疫法测定培养上清液中胰岛素浓度,并与相应的对照组比较。结果(1)培养液葡萄糖浓度为3.3 mmol／L,作用1 h,利培酮组和氯氮平组胰岛素分泌量与对照组比较,差异无显著性意义(均P>0.05);作用4 h,氯氮平抑制胰岛素分泌[相对胰岛素分泌量为65％(53％-73％)],差异有显著性意义(P<0.05)。培养液葡萄糖浓度为16.7 mmol／L,作用1 h或4 h,利培酮组和氯氮平组胰岛素分泌量与对照组比较,差异无显著性意义(均P>0.05)。(2)培养液葡萄糖浓度为3.3 mmol／L时,氯氮平作用4 h对胰岛素分泌的抑制程度明显低于作用1 h时[相对胰岛素分泌量为88％(77％~137％)],差异有非常显著性意义(P<0.01),其余的差异无显著性。结论 氯氮平抑制离体大鼠胰岛分泌胰岛素,而利培酮对之无影响;二者引起血糖代谢障碍的机制可能不同。     

IL-4基因修饰抗人脑胶质瘤效应的体外研究

目的 探讨人ＩＬ－４基因修饰对人脑胶质瘤的抑瘤效应及可能机制。方法 以逆转录病毒载体将人ＩＬ－４基因导入人脑胶质瘤细胞系ＳＨＧ４４细胞,用３Ｈ掺入法及流式细胞仪分析ＩＬ－４基因转染对人脑胶质瘤细胞增殖及细胞周期的影响;＾３Ｈ掺入法、＾５１Ｃｒ释放法检测ＩＬ－４基因修饰瘤苗对健康人外周血单个核细胞（ＰＢＭＣ）增殖、细胞毒性Ｔ细胞（ＣＴＬ）反应的影响。结果 与野生型瘤细胞比较,ＩＬ－４基因修饰瘤细胞增     

保存人鼻中隔软骨活性的3种体外方法比较*★

背景：软骨损伤后难以自身修复，以活性软骨进行修复效果较好，但活性软骨的可靠来源尚未根本解决。 目的：以3种不同方法体外保存成人鼻中隔软骨块的活性比较。 设计、时间及地点：单一样本观察，实验于2007-06/2008-03在解放军第四军医大学唐都医院耳鼻喉科实验室及西京医院全军耳鼻咽喉-头颈外科中心实验室完成。 材料：材料为临床常规手术中切除的成人正常鼻中隔软骨20块，按国务院2006年《医疗机构管理条例》规定，已与患者签订知情同意书。 方法：将所取软骨，块剪成大小约15 mm×10 mm×2 mm软骨块，分别置于4，-20，-80 ℃ 冷冻及RPMI-1640液于37 ℃培养保存，于保存24 h，7，14，21 d和30 d时取样品。 主要观察指标：以苏木精-伊红、AB/PAS及Masson 三色染色和锥虫蓝排斥试验检测软骨活性。 结果：用RPMI-1640培养液保存的成人鼻中隔软骨，在整个保存期中均能保持较好活性，软骨细胞活性率保持在80%左右。以-80 ℃冷冻保存7 d及-20 ℃保存14 d时，软骨基本失去活性, 当4 ℃保存在21 d时，软骨可保持较好活性，保存30 d时，软骨活性明显降低。 结论：与低温保存方法相比，用组织培养法保存成人软骨块能较好地保持其活性，有望为临床治疗提供一种取材方便、新型有效的软骨修复材料。     

The interrelationship between thromboxane biosynthesis, aggregation and 5-hydroxytryptamine secretion in human platelets in vitro

Platelet aggregation, secretion of 5-hydroxy tryptamine and production of thromboxane B2 were monitored simultaneously in human platelet suspensions in the absence and presence of cyclooxygenase or thromboxane synthetase inhibitors. Aggregation, secretion and thromboxane B2 formation in response to either sodium arachidonate or epinephrine were blocked by aspirin or by 1-N-butyl inidazole suggesting that thromboxane biosynthesis was an essential requirement for platelet activation by these agents. In contrast, thrombin and collagen could apparently induce aggregation and secretion via two pathways: at low doses involving thromboxane production, but at higher doses by a direct mechanism independent of thromboxane biosynthesis. In the case of ADP, inhibition of thromboxane production blocked secretion but had little effect on aggregation, indicating that secretion was probably dependent on thromboxane biosynthesis which probably occurred as a result of aggregation. Thus it appears that although the processes of thromboxane production, release of dense granule constituents and aggregation may often be intimately linked, each process can occur independently of the other, depending upon the stimulus used.     

Effect of various neurotransmitters and neuropeptides on the release of corticotropin-releasing hormone from the rat cortex in vitro.

Corticotropin-releasing hormone (CRH), in addition to its neuroendocrine role, may act as a central neurotransmitter. Cerebral cortical CRH may have an important role in behavioral and neurodegenerative disorders. To gain an understanding of factors that may influence cortical CRH, we investigated the effect of several neurotransmitters and neuropeptides on the release of immunoreactive CRH (iCRH) from various cerebral cortical regions [frontal (FC), parietal (PC), temporal (TC), and occipital (OC)] in vitro. The hypothalamic release of iCRH was also evaluated under the same experimental conditions. Basal release of iCRH was approximately 2-fold, and KCl-stimulated iCRH release was approximately 4-fold higher in the hypothalamus than in any of the cortical regions. Cortical iCRH release was stimulated by 10 nM somatostatin (SRIF) in PC and 1 nM neuropeptide Y (NPY) in TC. Cortical iCRH release was inhibited by 1 and 10 nM acetylcholine (ACh), 0.1 microM glutamate, and 10 nM NPY. These effects were confined to the FC and/or PC. Hypothalamic iCRH release was stimulated by 1 and 10 nM ACh, 10 microM GABA, and 1 and 10 nM serotonin but was inhibited by 10 nM SRIF and 1 microM GABA. Growth hormone-releasing hormone did not affect cortical or hypothalamic iCRH release. These results demonstrate that CRH release from the cerebral cortex and the hypothalamus are under different regulatory mechanism(s). Furthermore, they indicate that the release of CRH in various cortical regions may be regulated differentially by the same neurotransmitter.     

Acute effects of steroid hormones and neuropeptides on human social-emotional behavior: a review of single administration studies

Steroids and peptides mediate a diverse array of animal social behaviors. Human research is restricted by technical-ethical limitations, and models of the neuroendocrine regulation of social-emotional behavior are therefore mainly limited to non-human species, often under the assumption that human social-emotional behavior is emancipated from hormonal control. Development of acute hormone administration procedures in human research, together with the advent of novel non-invasive neuroimaging techniques, have opened up opportunities to systematically study the neuroendocrinology of human social-emotional behavior. Here, we review all placebo-controlled single hormone administration studies addressing human social-emotional behavior, involving the steroids testosterone and estradiol, and the peptides oxytocin and vasopressin. These studies demonstrate substantial hormonal control over human social-emotional behavior and give insights into the underlying neural mechanisms. Finally, we propose a theoretical model that synthesizes detailed knowledge of the neuroendocrinology of social-emotional behavior in animals with the recently gained data from humans described in our review.     

Chromatographic characterization of neuropeptides in post mortem human brain

Reverse phase high performance liquid chromatography was used to establish the immunoreactive species of five neuropeptides (thyrotropin-releasing hormone, luteinising hormone-releasing hormone, neurotensin, substance-P and somatostatin) in three areas of post mortem human brain--the hypothalamus, amygdala and cortex. In the majority of cases the major immunoreactive peak corresponded to the authentic peptide, although other peaks of immunoreactivity were observed in several instances. It was established that somatostatin-14 was present as the major immunoreactive form and that somatostatin-28 did not occur in any of the three brain areas, although other somatostatin-immunoreactive peaks of unknown structure were detected. In addition to authentic neurotensin in the cortex, a substantial peak of immunoreactivity corresponding to the elution time of neurotensin (1-11) was observed. LH-RH was not detected in the amygdala, but was present in the cortex as a minor component of overall immunoreactivity. The major peak of substance-P immunoreactivity in all three brain areas corresponded to authentic substance-P; in addition immunoreactive material eluting in the region of [Met-O] substance-P, substance-P (5-11) and substance-P (6-11) were detected. TRH occurred as the major peak in all three areas, although minor peaks of immunoreactivity were seen in the amygdala.     

Cerebral chemosensory evoked potentials elicited by chemical stimulation of the human olfactory and respiratory nasal mucosa

A stimulation method was employed by which chemosensory evoked potentials were recorded without tactile somatosensory contamination. The purpose of the study was to determine whether potential components evoked by stimulation of the chemoreceptors of the trigeminal nerve can be distinguished from those of the olfactory nerve. The stimulants (vanillin, phenylethyl alcohol, limonene, menthol, anethol, benzaldehyde, carbon dioxide and a mixture of vanillin and carbon dioxide) were presented in a randomized order to 13 volunteers. Chemosensory evoked potentials to substances which anosmics are unable to perceive (vanillin, phenylethyl alcohol) were termed olfactory evoked potentials; potentials to CO2, which effected no olfactory sensations were termed chemo-somatosensory potentials. Analysis of variance revealed that the different substances resulted in statistically significant changes in the amplitudes and latencies of the evoked potentials, and also in the subjective estimates of intensity. An increased excitation of the somatosensory system resulted in reduced latencies and enhanced amplitudes of the evoked potentials. Responses to the mixture of carbon dioxide and vanillin appeared significantly earlier (50-150 msec) than responses to either substance alone.