家兔若干与下行抑制有关的中枢部位中去甲肾上腺素、5-羟色胺和脑啡肽在针刺镇痛中的变化

应用推挽灌流技术、去甲肾上腺素(NA)放射酶学法和亮-脑啡肽放射免疫法观察不同脑区 NA 和脊髓背角亮-脑啡肽的释放。应用分子筛柱层析分离家兔不同脑区的5-羟色胺(5-HT)和5-羟吲哚乙酸(5-HIAA),并对它们进行荧光微量测定。以此来阐明针刺镇痛时 NA、5-HT 和亮-脑啡肽在下行抑制中的作用。1.家兔电针20 min,痛阈显著提高,此时中脑导水管周围灰质(PAG)和中缝大核(NRM)的 NA 释放显著减少,而 Al 核团和脊髓背角的 NA释放显著增加。2.电针镇痛时,PAG、延脑中缝核区和脊髓的5-HT 和5-HIAA 含量均有显著增加,除 PAG 外,这种增加的出现较 NA 为晚。提示可能在针刺镇痛的下行抑制中,NA 的参予较5-HT 为早。3.针刺镇痛时脊髓背角亮-脑啡肽的释放也明显增加。     

Relationship between hypothalamic noradrenergic neuronal activity and serum 3-methoxy-4-hydroxyphenylethylene glycol in the rat

It has been suggested that the circulating levels of 3-methoxy-4-hydroxyphenylethylene glycol (MHPG), a major end metabolite of noradrenaline (NA), may provide an index of central NA neuronal activity. The aim of this study was to examine in the rat the relationship between serum MHPG and hypothalamic NA neuronal activity during basal conditions, and when hypothalamic NA neuronal activity was stimulated or suppressed. Hypothalamic NA neuronal activity was assessed from the concentrations of the primary neuronal NA metabolite 3,4-dihydroxyphenylethyleneglycol (DHPG), MHPG, and the DHPG/NA and MHPG/NA ratios. Following 2-deoxyglucose (2DG) and cysteamine administration, hypothalamic NA neuronal activity and serum MHPG rose significantly. In contrast, hypothalamic NA neuronal activity and serum MHPG fell significantly in gentled rats. Serum MHPG correlated significantly with hypothalamic DHPG and the DHPG/NA ratio in control rats, and with hypothalamic DHPG, MHPG, and the DHPG/NA and MHPG/NA ratios in gentled, 2DG- and cysteamine-treated rats. In the latter two groups, serum MHPG also correlated significantly with serum glucose, which is itself closely related to hypothalamic NA neuronal activity. These studies demonstrate a significant relationship between serum MHPG and hypothalamic NA neuronal activity in the rat, so that serum MHPG provides an index of hypothalamic NA neuronal activity in the rat.     

Simultaneous determination of noradrenaline and 3-methoxy-4-hydroxyphenylglycol in plasma with high-performance liquid chromatography using electrochemical detection

We herein report the simultaneous determination of the levels of noradrenaline (NA), and 3-methoxy-4-hydroxyphenylglycol (MHPG), a major metabolite of NA. The sample was subjected to a Sep Pak C18 cartridge prior to the NA and MHPG assay by high-performance liquid chromatography with an electrochemical detector. The results correlated well with the established methods. The average percentage of recovery was 91.2 and 98.7% for NA and MHPG, respectively. The intraassay coefficients of variation were 3.7 and 4.6% for NA and MHPG. The interassay coefficients of variation were 3.5 and 7.5% for NA and MHPG, respectively.     

Acupuncture analgesia in rats and its changes under the effect of morphine and naloxone

It was established in chronic experiments on rats that electric acupuncture of the acupuncture point noticeably decreases pain reaction to electric stimulation of the tail. Morphine given in a subanalgetic dose (5 mg/kg) potentiated acupuncture analgesia, while 5 mg/kg of naloxone completely abolished it. Potential mechanisms of analgesia realization during electric acupuncture are discussed.     

Determination of the primary metabolite of central nervous system norepinephrine, 3-methoxy-4-hydroxy-phenethyleneglycol, in mouse brain and brain perfusate by high-performance liquid chromatography with electrochemical detection

Assays are described for the determination of picomole levels of 3-methoxy-4-hydroxy-phenethyleneglycol (MHPG) in mouse brain and in the perfusate of an intact mouse brain. High-performance liquid chromatography with electrochemical detection yielded a MHPG detection limit of 0.37 pmol. This technique offers a sensitive and inexpensive alternative to gas chromatography with mass spectrometry.     

Mass Fragmentographic Analysis of Monoamine Metabolites in the Spinal Cord of Rat After the Administration of Morphine

Abstract: A mass fragmentographic method was used in which homovanillic acid (HVA), methoxyhydroxyphenylglycol (MHPG), and 5-hydroxyindoleacetic acid (5-HIAA) were measured from a single sample. The results describe the effect of morphine on the metabolism of the major monoamines, dopamine (DA), noradrenaline (NA), and 5-hydroxytryptamine (5-HT) in the spinal cord. Morphine has very little effect on the metabolism of DA and NA in the spinal cord. However, morphine causes a significant increase in the metabolism of spinal 5-HT. The increase in 5-HIAA induced by morphine is not restricted to the dorsal horn. The three main functional regions of the cord—dorsal horn (sensory), zona intermedia (autonomic), and ventral horn (somatic motor)—are affected to the same degree. The results indicate that morphine causes a generalized activation of serotonin neurons in the spinal cord. There appears to be little or no selectivity for those serotonergic neurons that innervate the dorsal horn. The results are discussed with reference to current data which indicate a fairly strong link between descending serotonergic nerves and the mechanism of action of morphine-induced analgesia.     

Acupuncture modulates extracellular ATP levels in peripheral sensory nervous system during analgesia of ankle arthritis in rats

As an ancient analgesia therapy, acupuncture has been practiced worldwide nowadays. A good understanding of its mechanisms will offer a promise for its rational and wider application. As the first station of pain sensation, peripheral sensory ganglia express pain-related P2X receptors that are involved in the acupuncture analgesia mechanisms transduction pathway. While the role of their endogenous ligand, extracellular ATP (eATP), remains less studied. This work attempted to clarify whether acupuncture modulated eATP levels in the peripheral sensory nerve system during its analgesia process. Male Sprague–Dawley rats underwent acute inflammatory pain by injecting Complete Freund’s Adjuvant in the unilateral ankle joint for 2 days. A twenty-minute acupuncture was applied to ipsilateral Zusanli acupoint. Thermal hyperalgesia and tactile allodynia were assessed on bilateral hind paws to evaluate the analgesic effect. eATP of bilateral isolated lumbar 4-5 dorsal root ganglia (DRGs) and sciatic nerves were determined by luminescence assay. Nucleotidases NTPDase-2 and -3 in bilateral ganglia and sciatic nerves were measured by real-time PCR to explore eATP hydrolysis process. Our results revealed that acute inflammation induced bilateral thermal hyperalgesia and ipsilateral tactile allodynia, which were accompanied by increased eATP levels and higher mechano-sensitivity of bilateral DRGs and decreased eATP levels of bilateral sciatic nerves. Acupuncture exerted anti-nociception on bilateral hind paws, reversed the increased eATP and mechanosensitivity of bilateral DRGs, and restored the decreased eATP of bilateral sciatic nerves. NTPDase-2 and -3 in bilateral ganglia and sciatic nerves were inconsistently modulated during this period. These observations indicate that eATP metabolism of peripheral sensory nerve system was simultaneously regulated during acupuncture analgesia, which might open a new frontier for acupuncture research.     

Urinary excretion of bioactive amines and their metabolites in psychiatric patients receiving phenelzine

Phenelzine [2-phenylethylhydrazine] (PLZ), a potent inhibitor of monoamine oxidase (MAO)-A and-B, is used widely in psychiatry. We have studied the effects of PLZ administration on urinary excretion of several bioactive amines and their metabolites in psychiatric patients. Urine samples (24-hour) were collected prior to treatment and again at 2 and 4 weeks of treatment with PLZ (30–90 mg daily in divided doses). Amines and metabolites analyzed included 2-phenylethylamine (PEA), m-and p-tyramine (m-and p-TA), phenylacetic acid (PAA), m-and p-hydroxyphenylacetic acid (m-and p-OH-PAA), tryptamine (T), 5-hydroxytryptamine (5-HT), 5-hydroxyindoleacetic acid (5-HIAA), normetanephrine (NME), 3-methoxy-4-hydroxyphenylglycol (MHPG), 3-methoxytyramine (3-MT), and homovanillic acid (HVA). Levels of PEA, p-TA, 5-HT, and T were elevated during treatment with PLZ, but no significant changes in urinary excretion of the acid metabolites PAA, p-OH-PAA, and 5-HIAA were observed. Urinary levels of the noradrenaline metabolites NME and MHPG were increased and decreased, respectively; a similar pattern was observed with the dopamine metabolites 3-MT and HVA. There was an elevation in levels of m-TA and a decrease in its acid metabolite m-OH-PAA during the treatment with PLZ.     

HOMOVANILLIC ACID AND 3-METHOXY-4- HYDROXYPHENYLETHYLENEGLYCOL PRODUCTION BY THE MONKEY SPINAL CORD

The release of homovanillic acid (HVA) and 3-methoxy-4-hydroxyphenylethyleneglycol (MHPG) into CSF by the monkey spinal cord was investigated with spinal subarachnoid perfusion of 20 rhesus monkeys. The preperfusion concentration of HVA in lumbar CSF was 365 ng/ml and in cisternal CSF was 365 ng/ml, while the concentrations of MHPG were 28.3 and 40.4 ng/ml respectively. HVA originating from the spinal cord appeared in the perfusate at a rate of 2.4 and MHPG at 1.4 ng/min. Treatment with probenecid either intraperitoneally or intrathecally did not alter the rate of release into CSF of these metabolites by the spinal cord but did significantly increase the rate of appearance in the cisterna magna of HVA originating from the brain. MHPG and HVA in lumbar CSF are therefore derived in part from spinal cord metabolism.     

Neurotensin perfused in hypothalamus of sated or fasted rat: HPLC analysis of release of DA, NE and 5-HT and their metabolites

This investigation was undertaken in the unrestrained rat to determine the localized effect of neurotensin (NT) on the profile of release and turnover of norepinephrine (NE), dopamine (DA) and serotonin (5-HT) within the hypothalamus. Following stereotaxic implantation of a permanent guide tube, artificial CSF was perfused in the hypothalamus of the freely moving animal by means of push-pull cannulae at a rate of 20 μl/min and for an interval of 5.0 min. After three 5.0 min control samples were collected, NT in a concentration of 0.1 μg/μl was perfused followed by additional CSF controls. Assay by HPLC-EC of each perfusate showed that when the rat was sated, NT evoked a significant increase in the release of DA and DOPAC from the hypothalamus as well as augmented NE turnover, as reflected by a significant efflux in MHPG. However, when the rat was fasted for 22 hr, the perfusion of NT reduced DA and DOPAC concentrations in the diencephalic perfusate significantly as well as levels of both MHPG and VMA. Under both sated and fasted conditions, NT failed to produce notable changes in the release of 5-HT or its metabolism to 5-HIAA. These findings thus reveal a functional interaction between NT and both of the catecholamine neurotransmitters within hypothalamic neurons, which is clearly dependent upon the nutritional status of the animal.     

Increased Cerebrospinal Fluid Dopamine and 3,4-Dihydroxyphenylacetic Acid Levels in Huntington''s Disease: Evidence for an Overactive Dopaminergic Brain Transmission

Levels of dopamine (DA), 3,4-dihydroxyphenylacetic acid (DOPAC), homovanillic acid (HVA), noradrenaline (NA), 3-methoxy-4-hydroxyphenylglycol (MHPG), and 5-hydroxyindoleacetic acid (5-HIAA) in the CSF of patients with Huntington's disease (HD) were measured by HPLC. CSF DA, DOPAC, and MHPG levels were found to be increased in HD patients. Levels of HVA, 5-HIAA, and NA in the CSF of HD patients did not differ from those of controls. Changes in CSF DA and DOPAC levels were consistent with previous findings of increased DA tissue content in some brain areas of patients with HD. These results suggest that CSF DOPAC levels could be a more reliable index of overactive dopaminergic brain systems in HD than CSF HVA levels.     

Effects of naloxone-precipitated withdrawal after a single dose of morphine on catecholamine concentrations in guinea-pig brain

The effect of naloxone-precipitated withdrawal after acute morphine was studied on the concentrations of noradrenaline (NA), 4-hydroxy-3-methoxyphenylethyleneglycol (MHPG), dopamine (DA), 3,4-dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA), and on the metabolite/parent amine ratios MHPG/NA, DOPAC/DA and HVA/DA, in eight regions of the guineapig brain. Guinea-pigs were treated with a single dose of morphine sulphate (15 mg/kg s.c.) or saline (control) and 2h later with naloxone hydrochloride (15 mg/kg s.c.) to precipitate withdrawal. The animals were decapitated at 0.5 h or 1 h after naloxone injections and their brains analysed for monoamine concentrations by HPLC-ECD. At 0.5 h after naloxone-precipitated withdrawal NA and MHPG levels, and the MHPG/NA ratio, were increased in the hypothalamus, and the NA levels were increased in the hypothalamus, medulla/pons and cortex 1 h after naloxone. Naloxoneprecipitated withdrawal also produced increased DA metabolism in the cortex, midbrain and medulla 0.5 h later, and in the cortex, hypothalamus and striatum 1 h later. Hence naloxone-precipitated withdrawal from acute morphine treatment produced a complex pattern of increased synthesis and metabolism of NA and DA which varied over time and with the brain region examined.     

The role of alpha 1-adrenergic stimulation in inositol phosphate metabolism during post-ischaemic reperfusion.

The aim of this study was to elucidate the mechanism of enhanced inositol phosphate metabolism during reperfusion. Inositol phosphate stores were prelabelled by perfusing isolated rat hearts for 1 h with [3H]inositol (1.5 microCi/ml). LiCl (10 mM) and prazosin (0.3 microM) were subsequently added 15 min before (i) 20 min control perfusion; (ii) 20 min normothermic ischaemic cardiac arrest (NICA); (iii) 20 min NICA followed by 1 min reperfusion. The ventricles were freeze-clamped before determination of isotopical incorporation of [3H]inositol into the inositol phosphates (Dowex anion exchange chromatography) and InsP3 levels (Amersham InsP3 assay system). In addition, noradrenaline release into the perfusate was also assessed (HPLC and electrochemical detection). The results showed: (i) increased noradrenaline release into the perfusate immediately after the onset of reperfusion; (ii) significant depression of [3H]inositol incorporation into inositol phosphates and InsP3 levels after 20 min NICA; (iii) reperfusion caused an immediate significant increase in isotopical incorporation of [3H]inositol into inositol phosphates as well as InsP3 levels; (iv) the alpha 1-adrenergic blocker, prazosin (0.3 microM), completely inhibited the reperfusion-induced increase in inositol phosphate metabolism. These observations suggested that increased alpha 1-adrenergic receptor stimulation by noradrenaline might be responsible for the stimulation of ventricular inositol phosphate metabolism during postischaemic reperfusion.     

Catecholamine Content Changes in Brain Regions of Spontaneously Hypertensive Rats Under Immobilization Stress

We compared the effect of immobilization stress on noradrenaline (NA) and 3-methoxy-4-hydroxyphenylethyleneglycol (MHPG) content in two brain regions--diencephalon and pons-medulla oblongata--in young and adult spontaneously hypertensive rats (SHR) and Wistar-Kyoto rats (WKY). In SHR, NA content decreased with time after the onset of the stress, whereas levels of its metabolite MHPG increased. In WKY, NA and MHPG showed no change. The MHPG/NA ratio in both regions increased relative to the duration of the stress in SHR, whereas it remained almost constant in WKY. The rate of increase in the ratio was much higher in the diencephalon of adult (12-week-old) than of young (4-week-old) SHR. In SHR, NA turnover in the brain is readily affected by environmental stress, and these changes in the noradrenergic system may induce or sustain hypertension.     

Relationship of CSF neurotransmitter metabolite levels to disease severity and disability in multiple sclerosis

Axonal degeneration and brain tissue loss occur during disease progression in multiple sclerosis (MS) and are expected to influence neurotransmitter activities, with consequences on neurologic and psychiatric symptomatology. We searched for relationships of disease duration, disability, and severity of MS patients to CSF levels of the major metabolites of noradrenaline, dopamine, and serotonin, MHPG, methoxyhydroxyphenylglycol (MHPG), homovanillic acid, and 5-hydroxyindoleacetic acid (5-HIAA), respectively, in 39 patients with relapsing–remitting (RR) MS in remission, and 26 patients with progressive (PR) MS. Disability and Disease Severity were assessed by the Expanded Disability Status Scale (EDSS) and the Multiple Sclerosis Severity Score (MSSS). Compared with the levels of 50 control subjects, MHPG levels were not different in either MS group, correlated negatively to duration of illness and number of relapses in the RRMS group, but not to EDSS score or to MSSS. Homovanillic acid levels were significantly lower only in the PRMS group, with a negative correlation to duration of illness, and a strong negative correlation to EDSS score, but not to MSSS. 5-HIAA was significantly lower in both RRMS and PRMS groups. In the RRMS group, 5-HIAA levels were negatively related to EDSS and to MSSS. Multiple regression analyses revealed a significant association of MHPG to duration of illness, and a strong negative association of 5-HIAA to MSSS rather than to EDSS. The strong negative correlation of MSSS to CSF 5-HIAA levels in RRMS group of patients indicates that deficits in central serotonergic activity are related to the rate of disability accumulation in RRMS, and could be linked to the reported reduction of disease activity by serotonergic drugs.     

Effects of chlorpromazine on hypothalamic aminergic neurons and stress responses in moderate cold

Guinea-pigs were treated with chlorpromazine or 0.9% NaCl and exposed to +4 degrees C or +23 degrees C for 2 h. Hypothalamic noradrenaline (NA), dopamine (DA), 5-hydroxytryptamine (5-HT), 3-methoxy-4-hydroxyphenylethylene-glycol (MHPG), homovanillinic acid (HVA) and 5-hydroxyindoleacetic acid (5-HIAA) were determined by high-performance liquid chromatography. Serum and urinary catecholamines, muscle and liver glycogen and blood glucose were also measured. Chlorpromazine caused deep hypothermia at this moderately cold temperature and slight hypothermia at room temperature. Cold increased the activity of noradrenergic and serotonergic neurons, as indicated by the increase in hypothalamic MHPG and 5-HIAA and also the MHPG:NA and 5-HIAA:5-HT ratios. A tendency towards drug-induced inhibition of hypothalamic serotonergic neurons was seen, although this was not significant. A drug-induced inhibition of noradrenergic neurons could not be ruled out. Increased drug-induced turnover of DA was observed in the cold, and a tendency in the same direction was seen at room temperature. Excretion of DA into the urine was induced by chlorpromazine. The hypothermic guinea-pigs had low serum catecholamines, indicating diminished sympathetic activity, but high urinary catechols, a sign of cold stress.     

Biochemical studies on monoamine contents in spinal cord of patients with multiple system atrophy

Monoamine contents were measured in the cervical spinal cord of patients with multiple system atrophy (MSA) by high-performance liquid chromatography with electrochemical detection. The concentrations of noradrenaline (NA) and its metabolite 4-methyl-4-hydroxyphenylglycol (MHPG) were highest in ventral horn compared with other regions of the spinal cord in controls. Both NA and MHPG contents were reduced in all regions in 4 MSA patients. But in one case (case 5), which did not show an autonomic dysfunction, NA as well as MHPG level was similar to controls. Similarly, the concentrations of 5-hydroxytryptamine (5-HT) and its metabolite 5-hydroxyindoleacetic acid (5-HIAA) were highest in ventral horn and reduced in all regions in 4 MSA patients who showed mild motor weakness. In one case (case 5), which revealed clinical motor weakness associated with fasciculation and areflexia and pathological degeneration of ventral horn, 5-HT content showed higher values than controls whereas the 5-HIAA level was lower than controls. These results probably indicate that the cell loss of supraspinal monoaminergic nuclei may be one of the causes responsible for neurological dysfunction such as autonomic failures and motor weakness in MSA.     

The involvement of GABA(A) receptors in the control of GnRH and beta-endorphin release, and catecholaminergic activity in the ventromedial-infundibular region of hypothalamus in anestrous ewes.

To examine the role of the GABA(A) receptor mediating systems in the control of gonadotropin-releasing hormone (GnRH) release from the ventromedial-infundibular region (VEN/IN) of anestrous ewes, the extracellular concentrations of GnRH, beta-endorphin, noradrenaline (NE), dopamine (DA), 4-hydroxy-3-methoxy-phenylglycol (MHPG) and 3,4-dihydroxy-phenylacetic acid (DOPAC) were quantified during local stimulation or blockade of GABA(A) receptors with muscimol or bicuculline respectively. In most animals stimulation of GABA(A) receptors significantly attenuates GnRH release with concomitant increase of beta-endorphin and DA release, and MHPG and DOPAC levels. Blockade of the GABA(A) receptors generally did not affect GnRH and NE release but inhibited in most animals beta-endorphin release and decreased dopaminergic activity. These results suggest, that GABA may suppress GnRH release directly by GABA(A) receptor mechanism on the axon terminal of GnRH neurons or indirectly by GABA(A) receptor processes activating beta-endorphin-ergic and dopaminergic neurons in the VEN/NI. On the basis of these results in could not be distinguish between these two events. The decrease in extracellular beta-endorphin and dopamine concentration without evident changes in the GnRH level during GABA(A) receptor blockade may suggest that other neuronal systems are involved in this effect.     

脚内核在电针镇痛及兴奋尾壳核镇痛中的作用

用行为学和电生理学的方法 ,探讨脚内核在电针镇痛及兴奋尾壳核镇痛中的作用。脚内核微量注射红藻氨酸 7d后 ,电针对辐射热引起的大鼠缩腿潜伏期无明显影响 ,电针或兴奋尾壳核对丘脑束旁核神经元的伤害性反应亦无明显影响。与正常对照组电针或兴奋尾壳核产生的抑制作用相比有显著性差异 (P <0 .0 5 ) ;与脚内核微量注射生理盐水 7d后 ,电针可提高大鼠缩腿潜伏期 ,及电针或兴奋尾壳核对束旁核神经元伤害性反应的抑制作用相比 ,有显著性差异 (P <0 0 5 )。上述结果提示 ,脚内核在电针及兴奋尾壳核镇痛中发挥重要作用     

Ventricular Cerebrospinal Fluid Monoamine Transmitter and Metabolite Concentrations Reflect Human Brain Neurochemistry in Autopsy Cases

Concentrations of dopamine (DA), its metabolites 3-methoxytyramine and homovanillic acid (HVA), noradrenaline (NA), its metabolites normetanephrine (NM) and 3-methoxy-4-hydroxyphenylglycol (MHPG), 5-hydroxytryptamine (5-HT, serotonin), and its metabolite 5-hydroxyindoleacetic acid (5-HIAA) were measured in 14 brain regions and in CSF from the third ventricle of 27 human autopsy cases. In addition, in six cases, lumbar CSF was obtained. Monoamine concentrations were determined by reversed-phase liquid chromatography with electrochemical detection. Ventricular/lumbar CSF ratios indicated persistence of rostrocaudal gradients for HVA and 5-HIAA post mortem. Ventricular CSF concentrations of DA and HVA correlated positively with striatal DA and HVA. CSF NA correlated positively with NA in hypothalamus, and CSF MHPG with levels of MHPG in hypothalamus, temporal cortex, and pons, whereas CSF NM concentration showed positive correlations with NM in striatum, pons, cingulate cortex, and olfactory tubercle. CSF 5-HT concentrations correlated positively with 5-HT in caudate nucleus, whereas the concentration of CSF 5-HIAA correlated to 5-HIAA levels in thalamus, hypothalamus, and the cortical areas. These data suggest a specific topographic origin for monoamine neurotransmitters and their metabolites in human ventricular CSF and support the contention that CSF measurements are useful indices of central monoaminergic activity in man.