Interaction between cholinotropic and adrenotropic drugs on the histofluorescence of the central catecholamine structures in the rat

Male Wistar rats were given phentolamine or phenoxybenzamine in the lateral ventricles in doses of 1 mg/kg. After 30 minutes they received in the same way atropine in doses of 1 mg/kg or carbachol in doses of 0.05 mg/kg. The control group was given physiological saline. The animals were decapitated 30 minutes after drug administration. The Falck and Hillarp histofluorescence method was applied. The areas of DA (nigrostriatal and meso-limbic) and NA systems were examined. It was found, that atropine increased the intensity of fluorescence in comparison with the control group, in all areas of DA structures. The action of carbachol was more differentiated. In the substantia nigra (A8 and A9) respectively in the globus pallidus and the nucleus arcuatus (A12) its effect was the same as that of atropine. In other areas it caused weakening of fluorescence or showed no effect. In the NA system atropine weakened the fluorescence considerably while carbachol increased it in five out of eleven areas. The interaction of cholinotropic and adrenotropic drugs is disscused.     

Influence of atropine and carbachol on the fluorescence of catecholaminergic structures in selected areas of the rat brain.

Using the formaldehyde-fluorescence technique, the authors studied the influence of atropine and carbachol, administered intraventricularly to Wistar rats, on the fluorescence of catecholaminergic structures in 20 areas of the CNS, situated within the range of the 10th-46th frontal plane according to KONIG and KLIPPEL. 1. A confirmation of the antagonistic action of atropine and carbachol was obtained. It was expressed by mutually opposed occurrence of the specific fluorescence of the catecholaminergic structures. 2. In 16 out of 20 studied areas of the CNS, carbachol abolished or considerably weakened the specific fluorescence. In 3 areas it was increased by this drug, and one area proved insensitive. 3. Atropine increased the specific fluorescence in the DA (dopaminergic system) areas, while it had varying effects in the NA (noradrenergic system areas. In some areas of the CNS it increased and in others reduced the specific fluorescence of the catecholaminergic structures. 4. An interference between atropine and carbachol is observed, but it seems that the results of the present experiment speak in favour of an interaction between the catecholamine transmitters and ACh in the particular areas of the CNS under the influence of atropine and carbachol. 5. The authors discuss in detail the reactions of the catecholaminergic structures in the particular areas of the CNS, in which, as compared with the control, an increase or a decrease of the specific fluorescence under the influence of the administered drugs was observed.     

交感传出在大鼠糖尿病性痛过敏中的作用

交感传出和前列腺素（ＰＧｓ）在周围神经不全损伤和炎症所引起的痛过敏中起重要作用,它们对糖尿病性痛过敏影响尚不清楚。本工作先给大鼠腹腔注射６－羟多巴胺（６－ＯＨＤＡ）损毁交感节后神经元（ＳＰＧＮｓ）末梢后,再给予链脲佐菌素（ＳＴＺ）以建立６－ＯＨＤＡ糖尿病大鼠模型,在连续４周的观察中这组大鼠伤害性爪回缩阈值（ＮＰＷＴ）和甩尾反向潜伏期（ＴＥＬ）没有明显变化,而糖尿 病组大鼠的痛阈显著降低,并伴有痛过     

Neuromediator adaptation of the cerebral cortex and brain stem structures after radiation exposure]

In experiments with male Wistar rats a decreased receptor binding of 3H-corticosterone and impairment of neuromediator adaptation in the brain structures responsible for the regulation of animal and vegetative functions were observed 6 months after the effect of external radiation (0.5 Gy) and a mixture of external radiation and 131I (6.5 microCi/kg). These processes, being partly arrested by neurotropin, lay the neurochemical basis for the development of diencephalic syndrome.     

Alpha adrenoreceptor mediated alteration of ethanol effects on (Na+ + K+)-ATPase of rat neuronal membranes

Noradrenaline (NA) sensitizes rat brain (Na+ + K+)-ATPase to inhibition by ethanol (EtOH). This effect of NA increases with the degree of enrichment of the enzyme: 0.1 mM NA + 0.05 M EtOH produced 27% inhibition in whole brain homogenates, 40% in 2.5-fold purified P2 fractions, and 45% in 5-fold purified microsomal fractions. The sensitization by NA was prevented by 0.1 microM phentolamine but not by 100 microM propranolol. Adrenaline and phenylephrine also sensitized the enzyme to EtOH inhibition in all of the fractions but isoproterenol did not. For all three alpha agonists the degree of sensitization was concentration dependent and the degree of reversal of this effect varied with the concentration of phentolamine added. These findings suggest that the NA + EtOH interaction is a direct effect on the membrane, probably mediated by an alpha receptor modified perturbation of the membrane microenvironment of the enzyme.     

Mesenchymal stem cell therapy of brain ischemic stroke in rats

Mesenchymal stem cell (MSCs)-based therapy is a promising attempt to improve the recovery after stroke. Our experiments were carried out on inbred Wistar-Kyoto rats. MSCs were isolated, expanded in culture, and labeled with vital fluorescent dye PKH-26. Animals were subjected to middle cerebral artery occlusion (MCAO). After three days, MCAO 5 × 10⁶ isolated MSCs were injected into the tail vein of the experimental rats. The control animal group received PBS injections (negative control). Therapy results were evaluated by the following parameters: behavioral and neurological testing, the inured brain areas, damaged brain structures, neuron state, and vessel quantity in the region close to with necrosis zone. It was shown that control animals (PBS injection) did not return to their initial behavioral and neurological state within 6 weeks, while the experimental animals (MSCs injection), within 2–3 weeks after MCAO, had parameters like intact rats. The size of the damaged region in the control group was larger than in the experimental group by a factor of approximately 1.3. The damage in MSC-treated rats was limited to the neocortex; caudate nucleus, capsula externa and piriform cortex remained uninjured. The small vessel quantity in the “border” regions was twice as high as compared to the control group and approximately equal to the number of vessels in an intact brain. For the first time, we demonstrated that the vessel quantity in the neocortex and caudate nucleus of the contralateral hemisphere after MSC transplantation was twice as high as in control rats. It is concluded that the MSC transplantation exerts a beneficial influence upon the brain tissue reparation after stroke.     

Developmental and Regional Expression of NMDA Receptor Subtypes Containing the NR2D Subunit in Rat Brain

Abstract: The regional and developmental expression of NMDA receptors containing the NR2D subunit was analyzed on the level of the subunit mRNA and protein in rat brain. RNase protection experiments indicated that among two proposed splice variants of the NR2D subunit, only the NR2D-2 subunit is expressed. The regional distribution of the NR2D subunit protein was visualized with a newly developed NR2D-2 subunit-specific antiserum on brain sections using the histoblot technique. In adult brain, NR2D immunoreactivity was mainly restricted to diencephalic, mesencephalic, and brainstem structures. During postnatal development, the NR2D subunit was detected transiently in certain regions, such as the ventro-basal complex of the thalamus, hippocampus, inferior colliculus, and brainstem reticular formation, suggesting that NR2D subunit-containing receptors play a role in these brain areas only during development. The level of NR2D subunit mRNA and protein decreased during late postnatal development. However, significant levels of NR2D subunit mRNA and protein were present in adulthood, in particular, in the globus pallidus, thalamus, subthalamic nuclei, and superior colliculus. These results indicate a functional relevance for NMDA receptors containing the NR2D subunit in the developing and adult brain, although its expression in the adult brain is less prominent and restricted to a few brain areas.     

Significance of the reciprocal relationship of monoaminergic systems of the brain in the pharmacological compensation of 6-hydroxydopamine-induced behavior disorders in animals

The paper studied the methods of compensation of the abnormal emotional behaviour by means of pharmacological substances, which change the content of biogenic amines. The experiments made in the Wistar rats (n-54) whose frustration reaction was diminished by neonatal treatment of 6-OHDA. It was established that recovery of the disturbances in the frustration reaction in the animals with chronic brain system activity deprivation can be achieved not only by the activation of NA system (L-DOPA, DOPS) but also by deactivation of the 5-HT brain system activity (PCPA). These findings confirm suggestion about existence of reciprocal relationship between NA and 5-HT brain systems.     

Pressor effects of systemic administration of methionine and leucine enkephalin in the conscious rat

Experiments were designed using conscious Sprague-Dawley rats to determine the blood pressure (BP) and heart rate (HR) responses to intravenous doses of (1) the adrenal catecholamines noradrenaline (NA) and adrenaline (A), (2) adrenal pentapeptides methionine enkephalin (ME) and leucine enkephalin (LE), (3) combination (i.v.) injections of both ME or LE with NA or A that modulate the hemodynamic responses when the adrenal catecholamines were given alone, and (4) the possible receptor mechanisms mediating the resultant BP and HR response to i.v. pentapeptide administration. NA (0.48 and 2.4 nmol) and A (0.3 and 1.5 nmol) given i.v. evoked potent, dose-related pressor responses associated with reflex bradycardia. ME and LE (1.6 - 48 nmol) elicited transient (10-20 s) increases in mean arterial pressure (MAP), which was associated either with no change in mean heart rate (MHR), such as ME, or with slight bradycardia (i.e., LE). Combining ME or LE (16 nmol) with NA (2.4 nmol) or A (0.3 or 1.5 nmol) did not change MAP and MHR from when these respective doses of NA or A were given alone. However, 16 nmol of ME or LE with a low dose of NA (0.48 nmol) increased the pressor response compared with NA (0.48 nmol) given alone. Other experiments whereby specific receptor blockers (naloxone, diprenorphine, atropine, propranolol, phentolamine or guanethidine) were given i.v. 5 min before subsequent i.v. administration of LE or ME (16 nmol) indicated that only phentolamine or guanethidine could completely suppress the pressor responses of LE and ME. Naloxone and diprenorphine pretreatment attenuated the pressor response of LE but did not affect the BP response to ME.(ABSTRACT TRUNCATED AT 250 WORDS)     

选择性切除交感神经对大鼠心内神经节中去甲肾上腺素、乙酰胆碱和NPY的影响

为了探讨心内神经节中去甲肾上腺素（ＮＡ）、乙酰胆碱（ＡＣｈ）和ＮＰＹ的相互作用,本实验应用６－ＯＨ－ＤＡ选择性切除大鼠心脏交感神经纤维,然后应用荧光和酶组织化学法、免疫组织化学结合图像分析法观察了大鼠心内神经节ＮＡ、ＡＣｈＥ活性和ＮＰＹ的变化。结果显示：实验组大鼠心内神经节中儿茶酚胺荧光反应阳性和ＮＰＹ免疫反应（ＮＰＹ－ＩＲ）阳性的神经纤维明显减少,ＡＣｈＥ阳性神经纤维明显增多,ＡＣｈＥ反应性神经元积分光密度增加,而儿茶酚胺荧光反应和ＮＰＹ－ＩＲ阳性神经元变化不明显。结果提示：１．交感神经化学切除后大鼠心内神经节中ＮＡ、ＡＣｈＥ活性和ＮＰＹ出现不同的变化,体现了心脏交感神经和副交感神经的相互抑制作用;２．心内神经节可能含有两种性质的ＮＰＹ,即交感性和非交感性ＮＰＹ。     

Pharmacological suppression of eating behavior in relation to diencephalic noradrenergic receptors

The effect of the anorexigenic agents fenfluramine and dexamphetamine was studied on the eating behavior elicited by unilateral injections of noradrenaline in the perifornical area of the rat brain. Both agents were able to inhibit the eating response.Bilateral injections of the α-adrenergic receptor blocker phentolamine were performed into the perifornical area and the effect on eating behavior of rats under three different deprivation conditions was studied. Depression of eating behavior by phentolamine was most pronounced in the group of undeprived rats that were given mealworms as highly appetizing food and absent in the group of rats who were deprived of food for 24 hours. These results are discussed in relation to the role of the noradrenergic system in the regulation of food intake.     

Evidence for involvement of prostaglandins in central alpha adrenergic activity and LH release in sheep

Circhoral pulsatile release of immunoreactive luteinising hormone (LH) and prostaglandin F2 alpha (PGF2 alpha) occur synchronously into the jugular vein in ovariectomised sheep. Following a 4-hour control period, intra-carotid injections of phentolamine or intramuscular injections of phenoxybenzamine were given to ovariectomised sheep and the pulsatile release of LH and PGF2 alpha was monitored for a further 6 to 8 hours. Phenoxybenzamine caused a fall in LH and PGF2 alpha in jugular venous plasma. Phentolamine also reduced LH significantly but in this case a marked rise in PGF2 alpha as measured by radioimmunoassay (RIA) occurred after very high doses of phentolamine. Interpretation of the latter results was complicated by the fact that phentolamine at high dose levels interfered with the RIA of PGF2 alpha in plasma. Experiments were repeated in ovariectomised sheep with cannulae placed in the lateral ventricles of the brain for sampling cerebrospinal fluid (CSF). In contrast to the previously observed rise in jugular venous PGF2 alpha following high doses of phentolamine, a fall in CSF levels of immunoreactive PGF2 alpha occurred following intracarotid phentolamine or phenoxybenzamine in 3 out of 7 experiments, while no change was observed in the remaining 4 animals. Phentolamine did not reduce LH significantly in animals with intraventricular cannulae. The work provides support for the view that circhoral pulses of immunoreactive PGF2 alpha in sheep are neural in origin and may be related to sympathetic neurotransmission.     

The influence of prolonged hyper- and hypothyroid states on the noradrenaline content of rat tissues and on the accumulation and efflux rates of tritiated noradrenaline.

The influence of chronic hyper- and hypothyroidism on the uptake and retention of tritiated noradrenaline ([3-H]NA) and on the endogenous noradrenaline (NA) content of various adrenergically innervated tissues was studied in thyroidectomized and sham-operated euthyroid rats. Half of the thyroidectomized rats were treated daily with thyroxine (25 mug/kg) for 3 or 12 weeks to simulate a condition of chronic hyperthyroidism, while the other half was left untreated to form a hypothyroid group. The body weight and the heart rate of each rat were measured at the end of each experiment, and in addition, at the end of the 3 week experiment, the oxygen consumption and the plasma thyroxine levels were measured to confirm the thyroid state of the animals. At the end of both experiments, each animal was given an intravenous injection of [3-H]NA and the [3-H]NA and the total endogenous NA content of the heart and various other adrenergically innervated tissues were measured on a timed schedule, to compare the initial accumulations and the rates of efflux of [3-H]NA under different thyroid states. Although the hyperthyroid rats had higher heart rates and heart weights, they were not significantly different from the euthyroid controls with respect to their body weights, tissue NA content, or accumulation and efflux rates of [3-H]NA. In contrast, the hypothyroid rats showed significantly lower heart and other tissue weights, but higher tissue concentrations of NA and rates of efflux of [3-H]NA than the euthyroid group. In the hypothyroid state, the NA turnover appeared to be increased as the [3-H]NA efflux rate was increased from the hearts and adrenal glands. There were no significant differences between the results of the 3 week and the 12 week experiments and no evidence that prolongation of the hyperthyroid state gave different results from those found by other workers who used much shorter treatment periods and larger doses of thyroxine to develop hyperthyroidism.     

Liver peroxisomes in newborns from clofibrate-treated rats. I. A morphometric study of the recovery period.

Morphological and morphometric parameters (volume density (Vv), numerical density (NA) and mean diameter (D)) of newborn liver peroxisomes were measured throughout the first week of life in rats born to mothers treated with clofibrate (ethyl 2 p-chlorophenoxy isobutyrate) during the last five days of pregnancy. In control studies the same analyses were carried out in newborns from untreated rats. At birth (day 0), treated animals exhibited a proliferated, pleiomorphic peroxisomal population (higher Vv, NA and D, and a spread distribution of profile diameter with respect to the controls). In the subsequent two days, many peroxisomes disappeared (decrease of Vv and NA to values even lower than controls), with a persisting high pleiomorphism (no change of D and diameter distribution) in residual ones. Starting from day 3, and up to day 6, larger peroxisomes were no longer detectable in test animals, and a significant, not pleiomorphic proliferation took place (D and diameter distributions strictly comparable to the controls and progressively increasing Vv and NA). The correlation analysis validated these morphological results, from which it can be surmised that the postnatal peroxisome recovery period consists of a destructive phase followed by a proliferative one. The possible mechanism(s) of disposal of the excess of drug-induced peroxisomes are discussed.     

Catecholamine concentration in discrete brain areas following the withdrawal of barbital dependent rats

Noradrenaline (NA) and dopamine (DA) concentrations were measured in 5 discrete brain areas of barbital dependent rats following 0, 1 or 2 days of drug withdrawal. Statistically significant decreases in NA concentration were observed in the cerebral cortex and the thalamus of 1 day withdrawn rats while NA concentration in the hypothalamus was significantly reduced during the second day of withdrawal. The concentration of DA was significantly elevated in barbital dependent rats but declined following barbital withdrawal. Compared to control or nonwithdrawn rats, the concentration of DA in the thalamus was elevated by the second day of withdrawal. The changes in catecholamine concentration presumably reflect underlying effects of chronic barbital consumption or subsequent withdrawal on the synthesis, metabolism or utilization of these neurohumors.     

Effect of piracetam, a nootropic agent, on rat brain monoamines and prostaglandins

Piracetam is the prototype of a new class of psychotropic drugs, the nootropic agents, which are claimed to selectively improve the higher telencephalic integrative activities. The effect of piracetam on rat brain monoamines and prostaglandins (PGs) was assessed so as to garner information on its mode of action. Two doses of the drug were used, a lower dose (20 mg/kg ip) and a higher dose (100 mg/kg, ip), the latter being known to exert a facilitatory effect on learning and memory. Piracetam produced a dose-related effect on rat brain serotonin (5HT) and noradrenaline (NA), with the lower dose inducing a decrease in 5HT levels and an increase in NA concentrations. The higher dose of piracetam produced the opposite effect. Dopamine (DA) levels were not significantly affected. The lower dose of the drug attenuated 5HT turnover and augmented that of NA, whereas the higher dose of piracetam produced the reverse effects, in clorgyline treated rats. The lower dose of piracetam produced a slight and statistically insignificant increase in rat brain PGE2 and PGF2 alpha. However, the higher dose of the drug produced marked increase in the levels of both the PGs. The observed biochemical effects may provide a basis for the nootropic effect of piracetam. However, they may also be due to the GA-BA-mimetic action of the drug, particularly those observed with the lower dose of piracetam.     

Effect of carbidine on the process of adrenergic neurotransmission]

Methods of physiological analysis were applied to a study of the effect of an original psychotropic agent--carbidine--on the process of adrenergic neurotransmission on a model of an isolated rat Vas deferens. The noradrenaline (NA) content was determined in the same ductus spectrofluorimetrically; the capacity of the neuroleptic to block the consumption of the exogenous NA by the tissue was also investigated. Carbidine proved to possess an adrenomimetic effect caused by it capacity to release NA, leading to a reduction of endogenous neuromediator stores.     

Acetylcholine in the brain of rats exposed to acute irradiation

A two-fold increase in acetylcholine, that can randomly be released by brain synaptosomes, is registered 60 min following whole-body X-irradiation of rats with a dose of 0.21 C/kg; depolarization of the synaptosome membranes by potassium chloride increases the release of acetylcholine the augmentation of the release in this case being lower than that in the control. The initial rate of spontaneous neuromediator release from synaptosomes grows by 80 per cent whereas after depolarization of synaptosome membranes by potassium chloride, by 15 per cent. There is a 2.5-fold increase in the maximum rate of a highly specific uptake of choline with Km value being constant. Acetylcholine content of gray substance of irradiated rat brain is invariable.     

The interstrain differences in the effects of D-amphetamine and raclopride on dorsal striatum dopaminergic system in KM and Wistar rats (microdialysis study)

The levels of dopamine (DA) was determined by intracerebral microdialysis in vivo in KM rats selected for high audiogenic epilepsy, and in Wistar rats selected for nonsusceptibility to loud sound. The basal level of dopamine was 25% higher in the KM rats (P < 0.05). A single amphetamine injection (1 mg/kg body weight, intraperitoneously) caused a significant increase in the DA basal level up to 250-260% in animals of both genotypes. However, in Wistar rats, the level of DA reached maximum as soon as 20 min after amphetamine administration, whereas in KM rats, this happened only after 120 min. After a single injection of the antagonist of D2 and D3 dopamine receptors raclopride (1.2 mg/kg of body weight, intraperitoneously), an increase in the level of DA was similar in amplitude in rats of both genotypes (up to about 210%); however, this occurred 20-30 and 100 min after raclopride administration to Wistar and KM rats, respectively. This evidence suggests that the genetic defect of KM rats, namely, the high level of audiogenic epilepsy, is caused by abnormalities of the neuromediator brain systems and presumably accompanied by the regulatory gene dysfunction.     

Determination of Normetanephrine, 3,4-Dihydroxyphenylethyleneglycol (Free and Total), and 3-Methoxy-4-Hydroxyphenylethyleneglycol (Free and Total) in Rat Brain by High-Performance Liquid Chromatography with Electrochemical Detection and Effects of Drugs on Regional Concentrations

A new, fast and sensitive assay for normetanephrine (NM), free and total 3,4-dihydroxyphenylethyleneglycol (DOPEG), and free and total 3-methoxy-4-hydroxyphenylethyleneglycol (MOPEG) in brain tissue is described. The method is based on high-performance liquid chromatography with electrochemical detection. Small Sephadex G 10 columns were used for prepurification. This permitted the additional isolation and quantification of tyrosine, 3,4-dihydroxyphenylalanine, noradrenaline, dopamine, 3-methoxytyramine, 3,4-dihydroxyphenylacetic acid, homovanillic acid, and 5-hydroxyindoleacetic acid. The compounds were determined in six brain areas (striatum, cortex, hippocampus, hypothalamus, brainstem, and cerebellum). Most DOPEG and MOPEG in rat brain was present in the conjugated form, except for the cerebellum, where about 80% of MOPEG was nonconjugated. No postmortem effects on MOPEG levels were observed; a slight increase in DOPEG in certain brain areas was found in microwave-killed rats. The effects of clonidine, yohimbine, N,N-dipropyl-5,6-ADTN, and chlorpromazine on the concentrations of the five noradrenaline (NA) metabolites were determined. Free and total DOPEG and MOPEG provide similar information on NA metabolism, whereas NM (after monoamine oxidase inhibition) reflects a different type of interaction of drugs with NA metabolism. The similarity in the pattern of drug-induced changes in NA metabolism in the various brain areas suggests that adrenoreceptors mediating NA metabolism are homogeneously distributed throughout the brain.