吗啡和胆碱能拮抗剂联合给药对小鼠Y迷宫空间记忆提取及活动性的影响(英文）

吗啡和胆碱能系统的相互作用已在多项研究中提到,本实验想查明吗啡是否能和胆碱能拮抗剂、东莨菪碱以及阿托品共同作用对小鼠的Y迷宫空间识别记忆提取产生影响。采用测试前腹腔给药的方法,选用3种剂量的吗啡(5、1.5、0.5mg/kg),两种剂量的东莨菪碱(1、0.1mg/kg),以及两种剂量的阿托品(0.5、0.1mg/kg),剂量由高到低相配对作为联合给药的手段。其结果表明:1)0.5mg/kg低剂量吗啡与0.1mg/kg低剂量的东莨菪碱,或与0.1mg/kg低剂量的阿托品联合给药的小鼠,在记忆提取测试中,空间探查行为(各臂停留时间百分比)对新异臂没有偏好,而新奇探索行为(各臂访问次数百分比)仍保持了对新异臂的偏好,而相应剂量药物单独给药的小鼠记忆提取均没有被损害;2)吗啡能和东莨菪碱相互作用使小鼠的活动性显著增强。暗示吗啡和胆碱能拮抗剂对小鼠空间记忆提取的破坏存在一定程度的相互作用。     

Caffeine-induced locomotor activity: Possible involvement of GABAergic-dopaminergic-adenosinergic interaction

Caffeine (10–40 mg/kg, p.o.) enhanced locomotor activity (LA). Administration of GABA antagonist, bicuculline (0.5–1.0 mg/kg, i.p.), potentiated this caffeine-induced increase of LA, as well as LA of control rats. Treatment with the GABA agonist, muscimol (0.25–1 mg/kg, i.p.) or dopaminergic antagonist, haloperidol (0.25–1 mg/kg, i.p.) or muscarinic receptor blocker, atropine (3.75–5 mg/kg, i.p.), or inhibitor of acetylcholine esterase physostigmine (0.05–0.30 mg/kg, i.p.) or nicotine (0.5–1.5 mg/kg, i.p.) an nicotinic receptor agonist all decreased the LA of both caffeinetreated and control rats. Haloperidol-induced reduction in caffeine-induced increase in LA was found to be withdrawn with higher dose of caffeine. The dopamine agonist L-Dopa (75–150 mg/kg, p.o.) along with carbidopa (10 mg/kg, p.o.) increased the LA in control rats and potentiated the LA of caffeine treated rats. The haloperidol attenuated the bicuculline-induced increase in LA and atropine or physostigmine attenuated the bicuculline or L-Dopa+carbidopa-induced increase in LA in both caffeine treated and control rats when those drugs were administered concomitantly with bicuculline or L-Dopa+carbidopa. These results suggest that (a) the GABAergic system has direct role in the regulation of LA, and (b) caffeine potentiates LA by antagonism of the adenosine receptor and activation of the dopaminergic system which, in turn, reduces GABAergic activity through the reduction of cholinergic system.     

Sex differences in the cholinergic status of white rats]

Female rats injected with organophosphate inhibitor of acetylcholinesterase chlorophose at doses of 10 mg/kg and 360 mg/kg showed less considerable decrease in blood acetylcholinesterase activity than did male animals. Females compared with males also demonstrated less expressed clinical symptoms of poisoning (salivation, convulsion) after injection of chlorophose at dose of 360 mg/kg. The value of LD50 in female rats was 860 mg/kg, whereas the comparable value in male animals was 700 mg/kg. Following the injection of atropine at doses of 0.1, 0.3, 0.6 mg/100 g female rats showed 2-3 fold increases in basal adrenal and plasma corticosterone levels, but significant decreases in stress-induced corticosterone levels. As for males, the basal and stress-induced values of corticosterone were not significantly affected by atropine administration. These results suggest that functional reserves of cholinergic system and responsiveness of the hypothalamic-pituitary-adrenal axis to cholinergic influence are greater in females than in males. It is concluded that cholinergic status is significantly higher in female rats than in male ones.     

Relationship between cortical electrical and cardiac autonomic activities in the awake lizard, Gallotia galloti

ECG and EEG signals were simultaneously recorded in lizards, Gallotia galloti, both in control conditions and under autonomic nervous system (ANS) blockade, in order to evaluate possible relationships between the ANS control of heart rate and the integrated central nervous system activity in reptiles. The ANS blockers used were prazosin, propranolol, and atropine. Time-domain summary statistics were derived from the series of consecutive R-R intervals (RRI) of the ECG to measure beat-to-beat heart rate variability (HRV), and spectral analysis techniques were applied to the EEG activity to assess its frequency content. Both prazosin and atropine did not alter the power spectral density (PSD) of the EEG low frequency (LF: 0.5-7.5 Hz) and high frequency (HF: 7.6-30 Hz) bands, whereas propranolol decreased the PSD in these bands. These findings suggest that central beta-adrenergic receptor mechanisms could mediate the reptilian waking EEG activity without taking part any alpha(1)-adrenergic and/or cholinergic receptor systems. In 55% of the lizards in control conditions, and in approximately 43% of the lizards under prazosin and atropine, a negative correlation between the coefficient of variation of the series of RRI value (CV(RRI)) and the mean power frequency (MPF) of the EEG spectra was found, but not under propranolol. Consequently, the lizards' HRV-EEG-activity relationship appears to be independent of alpha(1)-adrenergic and cholinergic receptor systems and mediated by beta-adrenergic receptor mechanisms.     

Carbaryl-induced elevation of corticosterone level and cholinergic mechanism

Administration of a single dose (200 mg/kg, p.o.) of carbaryl to rats produced a significant rise in adrenal and plasma corticosterone levels and an increase of tyrosine alpha-ketoglutarate transaminase activity in the liver cytosol. Synaptosomal acetylcholinesterase activity of the hypothalamic and the striatal regions of rat brain was decreased by carbaryl treatment under similar conditions. Pretreatment (0.5 h) with atropine sulphate (10 mg/kg, i.p.) failed to counteract the carbaryl-induced elevation of adrenal and plasma corticosterone levels and hence the liver tyrosine alpha-ketoglutarate transaminase activity. Present results suggest that the carbaryl-induced rise in the corticosterone level in the adrenal gland and plasma is not due to a cholinergic mechanism.     

Regulation of Histamine Turnover via Muscarinic and Nicotinic Receptors in the Brain

To clarify the regulation of central histaminergic (HAergic) activity by cholinergic receptors, the effects of drugs that stimulate the cholinergic system on brain histamine (HA) turnover were examined, in vivo, in mice and rats. The HA turnover was estimated from the accumulation of tele-methylhistamine (t-MH) during the 90-min period after administration of pargyline (65 mg/kg, i.p.). In the whole brain of mice, oxotremorine, at doses higher than 0.05 mg/kg, s.c., significantly inhibited the HA turnover, this effect being completely antagonized by atropine but not by methylatropine. A large dose of nicotine (10 mg/kg, s.c.) also significantly inhibited the HA turnover. This inhibitory effect was antagonized by mecamylamine but not by atropine or hexamethonium. A cholinesterase inhibitor, physostigmine, at doses higher than 0.1 mg/kg, s.c., significantly inhibited the HA turnover. This effect was antagonized by atropine but not at all by mecamylamine. None of these cholinergic antagonists used affected the steady-state t-MH level or HA turnover by themselves. In the rat brain, physostigmine (0.1 and 0.3 mg/kg, s.c.) also decreased the HA turnover. This inhibitory effect of physostigmine was especially marked in the striatum and cerebral cortex where muscarinic receptors are present in high density. Oxotremorine (0.2 mg/kg, s.c.) and nicotine (1 mg/kg, s.c.) also decreased the HA turnover in the rat brain. However, these effects showed no marked regional differences. These results suggest that the stimulation of central muscarinic receptors potently inhibits the HAergic activity in the brain and that strong stimulation of central nicotinic receptors can also induce a similar effect.     

Effect of subdiaphragmatic vagotomy and cholinergic agents in the hypothalamic-pituitary-adrenal axis activity.

In the present study, we examined whether the vagus nerve is involved in mediating the stimulation of hypothalamic-pituitary-adrenal (HPA) axis by cholinergic muscarinic and nicotinic agonists, carbachol and nicotine. The site of HPA axis muscarinic stimulation was determined using peripheral (i.p.) and intracerebroventricular (i.c.v.) administration of carbachol, atropine sulphate (AtrS) and atropine hydrobromide (AtrBr). The i.p. carbachol-(0.5 mg/kg)-induced corticosterone response was significantly reduced by i.p. pretreatment with AtrBr (0.1 mg/kg), but was not diminished by i.c.v. AtrS (0.1 mug). The increase in corticosterone secretion induced by i.c.v. carbachol (2 microg) was totally abolished by i.c.v. pretreatment with AtrS (0.1 microg) but was not altered by i.p. AtrBr. Subdiaphragmatic vagotomy performed 2 weeks earlier substantially decreased the i.p. carbachol (0.2 mg/kg)-induced ACTH response and markedly augmented ACTH and corticosterone response to a higher dose of carbachol (0.5 mg/kg) in comparison with the responses in sham operated rats. Vagotomy abolished the stimulatory effect of i.p. nicotine in a low dose (1 mg/kg) on ACTH and corticosterone secretion; the ACTH response to higher dose (2.5 mg/kg) was considerably reduced, while corticosterone response remained unaffected. These results suggest that carbachol given i.c.v. evokes considerable corticosterone response by stimulation of central cholinergic muscarinic receptors. A major part of the i.p. carbachol-induced corticosterone secretion results from peripheral cholinergic muscarinic receptor stimulation. Subdiaphragmatic vagotomy moderately intensified the carbachol-induced ACTH and corticosterone secretion. Vagotomy significantly reduced the nicotine-induced ACTH secretion, possibly by the involvement of vagal afferents. The nicotine-induced corticosterone secretion is not exclusively regulated by circulating ACTH but by various intra-adrenal regulatory components.     

Biphasic effects of atropine on sensory-evoked hippocampal rhythmical slow activity in urethane-anaesthetized rats

This study investigated the response of hippocampal RSA, recorded from electrodes in CA1 and the contralateral dentate gyrus of urethane-anaesthetized rats, to atropine sulphate administered at 15 min intervals in a cumulative dose-response schedule (1, 3, 10, 50 and 50 mg x kg(-1) i.p.). The power of CA1 and dentate gyrus RSA in the 3-7 Hz band was increased after administering the first 3 doses of atropine (1, 3 and 10 mg x kg(-1) cumulatively) in rats held in the stereotaxic frame or removed from the frame and given electrical sensory stimulation to the base of the tail. This increase in RSA was dependent on sensory input, since it was not seen in animals outside the frame unless sensory stimulation was given, and it was abolished by increasing the dose of atropine (an additional 50 and 50 mg x kg(-1) cumulatively). Methylatropine (6 mg x kg(-1) i.p.) did not increase RSA power. The biphasic effect of atropine on sensory-evoked hippocampal RSA activity may be explained by differential effects at pre- and post-synaptic sites e.g. in the septo-hippocampal system or on pathways processing sensory information.     

Reduction by atropine of phencyclidine hypertension and apneusis

The aim of this study was to assess the possible role of a central cholinergic component phencyclidine (PCP)-induced hypertension. Sprague-Dawley rats, lightly anesthetized with urethane, exhibited a dose related pressor response following 0.1–1.0 mg/kg PCP i.v. After i.v. atropine pre-treatment, the PCP dose-response curve was shifted to the right, and the magnitude of the pressor responses was reduced by about 50%. In addition, atropine reduced the incidence of apneusis, but had no effect on the bradycardia that accompanied the pressor responses. Methylatropine (i.v.) did not reduce the PCP pressor responses, nor did it prevent the apneusis induced by PCP. These results suggest that in addition to its direct pressor effects the activation of central cholinergic systems contribute significantly to the cardiovascular and respiratory toxicity induced by PCP.     

The GABA-ergic system and brain edema

It has been shown in rats with experimental toxic and traumatic edemas that picrotoxin (1 mg/kg) removes the antiedematous action of diazepam, phenazepam, phenibut and amizyl and reduces the action of phentolamine. When the dose of picrotoxin is minimized to 0.5 mg/kg such an effect is not observed. Prolonged daily administration of picrotoxin in a dose of 1 mg/kg results in the development of brain edema. It is recommended that GABA-positive drugs be included into a complex of treatment measures for edema.     

Effect of gamma-aminobutyric acid and muscimol on corticosterone secretion in rats.

The effect of gamma-aminobutyric acid-receptor agonists, GABA and muscimol on the pituitary-adrenocortical activity, measured indirectly through corticosterone secretion, and the receptors involved were investigated in conscious rats. GABA given ip induced a dual effect, in lower dose (10 mg/kg) it significantly decreased the resting serum corticosterone levels while in higher doses (100-500 mg/kg) it considerably raised that level. Muscimol (0.5 mg/kg ip) also increased the corticosterone concentration. Both GABA and muscimol given intracerebroventricularly (icv) induced a significant, dose-related increase in serum corticosterone levels. Bicuculline, a GABAA-receptor antagonist, totally abolished the corticosterone response to GABA but did not influence the response to muscimol. Pretreatment with atropine did not affect the corticosterone response to GABA but significantly diminished the response to muscimol. These results suggest that GABA moderately inhibits the pituitary-adrenal axis at the pituitary level but significantly stimulates it at the hypothalamic level. The stimulatory effect of GABA, but not muscimol, is mediated by hypothalamic GABAA-receptors, and in the effect of muscimol hypothalamic cholinergic, muscarinic receptors are involved to a significant extent.     

Effect of autonomic blockers on heart period variability in calves: evaluation of the sympathovagal balance

This study was designed to validate the measures of heart period variability for assessing of autonomic nervous system control in calves. Eight calves received an injection of either 0.5 mg/kg atenolol (sympathetic tone blockade), 0.2 mg/kg atropine sulfate (parasympathetic tone blockade), 0.5 mg/kg atenolol + 0.2 mg/kg atropine sulfate (double autonomic blockade) or saline. In the time-domain, we calculated the mean instantaneous heart rate (HR), mean of RR intervals (MeanRR), standard deviation of RR intervals (SDRR) and that of the difference between adjacent intervals (RMSSD). In the frequency-domain, the power of the spectral band 0-1 Hz (TPW), the power of the 0-0.15 Hz band (LF), that of the 0.15-1 Hz band (HF), and the LF/HF ratio were considered. The net vago-sympathetic effect (VSE) was calculated as the ratio of MeanRR in a defined situation to MeanRR during the double blockade. Atenolol injection had no effect on cardiac activity, whereas atropine induced large modifications which were moderated when atenolol was administered at the same time. VSE, HR, MeanRR and RMSSD were found to be valid indicators of the parasympathetic tone of calves because of large variations due to the drug and low individual variations. No measure reflected the sympathetic tone.     

Immune responses in mice to arecoline mediated by lymphocyte muscarinic acetylcholine receptor

There is evidence that lymphocytes possess all the components of the cholinergic system independent of neuronal innervations. Thus, potential therapeutic applications of drugs targeting the neuronal cholinergic system might have side effects on the immune system. This study investigated whether arecoline could affect immunological functions in mice and explored the mechanism of the effect of arecoline on the immune system. To investigate this, arecoline at the dose of 2mg/kg was administered subcutaneously in BALB/c mice for 4 weeks to evaluate changes in immunological function both in vivo and in vitro. Several indices were used to assess immunological activation, including the spleen index, serum hemolysin levels, interleukin (IL)-2 and splenocyte proliferation. Our results showed a significant reduction in treated animals with respect to the control group in the following tests: the spleen index (86%), hemolysin against sheep red blood cells (68%), IL-2 production (73%), and splenocyte proliferation induced by concanavalin A or lipopolysaccharide (76% and 74%, respectively). The muscarinic receptor antagonist atropine (1mg/kg) reversed the inhibition of the four immune-related parameters mentioned above. Chronic atropine alone did not significantly affect the immune response. To our knowledge, this is the first study to demonstrate that arecoline interferes with the immune system by targeting the muscarinic acetylcholine receptors of the non-neuronal cholinergic system.     

The effects of various cognition-enhancing drugs on in vitro rat hippocampal synaptosomal sodium dependent high affinity choline uptake

The purpose of the present study was to compare the effect of seven drugs, that have been reported to enhance cognitive functions, on rat hippocampal cholinergic neuronal activity. The latter was assessed by measuring the effects of the drugs on in vitro sodium-dependent high affinity choline uptake (HACU) into rat hippocampal synaptosomes 30 minutes after their in vivo administration. 3,4-Diaminopyridine (0.1 mg/kg IP), like pramiracetam (44 and 88 mg/kg IP), increased HACU with higher or lower doses being ineffective. Centrophenoxine (100 mg/kg IP) decreased HACU. Piracetam (100 and 500 mg/kg IP), aniracetam (10-200 mg/kg PO), lysine vasopressin (0.005-0.05 mg/kg IM) and 4-aminopyridine (0.01-3.0 mg/kg IP) were ineffective. The results indicate that 3,4-diaminopyridine and centrophenoxine, like pramiracetam may be increasing cognitive function in part by affecting hippocampal cholinergic neuronal activity. In addition, the findings indicate the usefulness of using in vitro HACU as a biochemical measurement to assess the potential effect of cognitive-enhancing drugs on cholinergic neuronal activity in vivo.     

Impact of gender on the cardiac autonomic response to angiotensin II in healthy humans

Premenopausal women have a lower risk of cardiovascular disease (CVD) compared with men of a similar age. Furthermore, the regulation of factors that influence CVD appears to differ between the sexes, including control of the autonomic nervous system (ANS) and the renin-angiotensin system. We examined the cardiac ANS response to angiotensin II (Ang II) challenge in healthy subjects to determine whether differences in women and men exist. Thirty-six healthy subjects (21 women, 15 men, age 38 ± 2 years) were studied in a high-salt balance. Heart-rate variability (HRV) was calculated by spectral power analysis [low-frequency (LF) sympathetic modulation, high-frequency (HF) parasympathetic/vagal modulation, and LF:HF as a measure of overall ANS balance]. HRV was assessed at baseline and in response to graded Ang II infusions (3 ng·kg(-1)·min(-1) × 30 min; 6 ng·kg(-1)·min(-1) × 30 min). Cardiac ANS tone did not change significantly in women after each Ang II dose [3 ng·kg(-1)·min(-1) mean change (Δ)LF:HF (mean ± SE) 0.5 ± 0.3, P = 0.8, vs. baseline; 6 ng·kg(-1)·min(-1) ΔLF:HF (mean ± SE) 0.5 ± 0.4, P = 0.4, vs. baseline], whereas men exhibited an unfavorable shift in overall cardiac ANS activity in response to Ang II (ΔLF:HF 2.6 ± 0.2, P = 0.01, vs. baseline; P = 0.02 vs. female response). This imbalance in sympathovagal tone appeared to be largely driven by a withdrawal in cardioprotective vagal activity in response to Ang II challenge [ΔHF normalized units (nu), -5.8 ± 2.9, P = 0.01, vs. baseline; P = 0.006 vs. women] rather than an increase in sympathetic activity (ΔLF nu, -4.5 ± 5.7, P = 0.3, vs. baseline; P = 0.5 vs. women). Premenopausal women maintain cardiac ANS tone in response to Ang II challenge, whereas similarly aged men exhibit an unfavorable shift in cardiovagal activity. Understanding the role of gender in ANS modulation may help guide risk-reduction strategies in high-risk CVD populations.     

Catalepsy induced by morphine or haloperidol: effects of apomorphine and anticholinergic drugs.

To investigate the extent of cholinergic involvement in opiate-induced catalepsy, the effects of three anticholinergic drugs were studied on morphine-induced catalepsy. Haloperidol-induced catalepsy was also examined. Maximum catalepsy in rats was obtained with 30 mg/kg morphine or 3 mg/kg haloperidol. The anticholinergic drugs atropine, benztropine, and scopolamine were unable to antagonize morphine-induced catalepsy, yet readily antagonized haloperidol-induced catalepsy. Low doses of apomorphine (7.5 mg/kg), on the other hand, readily antagonized morphine catalepsy, but 13-fold higher doses of apomorphine were needed to block haloperidol-induced catalepsy. The results are compatible with the idea that catalepsy can be mediated via the striatum or the amygdala; morphine-dopamine antagonism may occur in the amygdala, whereas morphine-dopamine-cholinergic interactions occur in the striatum.     

D1 agonist SKF 38393 antagonizes pentobarbital-induced narcosis and depression of hippocampal and cortical cholinergic activity in rats

SKF 38393 (5 mg/kg), but not quinpirole, shortened the duration of loss of righting reflex produced in pentobarbital-narcotized rats. This effect was blocked by atropine (2 mg/kg), but not by atropine methylbromide, suggesting involvement of central cholinergic mechanisms. The analeptic effect was also blocked by SCH 23390 (0.2 mg/kg) or raclopride (2 mg/kg). SKF 38393 also increased sodium dependent high affinity choline uptake (HACU) in cortical and hippocampal synaptosomes that had been depressed by pentobarbital. SCH 23390 or raclopride prevented the SKF 38393 reversal of the depressed HACU, indicating that both D1 and D2 mechanisms were involved mediating the analeptic effect. These results provide neurochemical evidence that cortical and hippocampal D1-mediated cholinergic activation results in a behavioral arousal (analeptic) response. They also suggest that DA mechanisms may be involved in regulation of cortical and hippocampal cholinergic neurons.     

Mechanism of action of naphthylvinylpyridine]

Naphthylvinylpyridine (NVP) in the cat cerebral cortex (50 mg/kg) and in the mouse brain (100 and 250 mg kg) caused inhibition of choline acetyltransferase (ChA) and didn't influence the acetyl- and butyrilcholinesterase activity and acetylcholine (Ach) content in the mouse brain. NVP (25 mg/kg) failed to influence the ChA activity. Pretreatment with NVP (25 and 250 mg/kg) increased the duration of hexenal sleep in mice greatly, and a dose of 250 mg/kg (but not of 25 mg/kg) enhanced the atropine activity in mice poisoned with armine. NVP (250 mg/kg) reduced the release of Ach from the cerebral cortex of a cat, spontaneous and evoked by atropine and electrical stimulation of the reticular formation of the brain stem. A conclusion was drawn that the pharmacological effect of NVP when the latter was applied in combination with atropine and armine could be connected with the anti-Cha action and the inhibition of the newly-formed Ach, rather than with depression of the microsomal enzymes.     

Antidote effect of sodium fluoride against organophosphate poisoning in mice

Pretreatment of mice with atropine (17.4 mg/kg) + NaF (5 or 15 mg/kg) had a significant antidotal effect over atropine alone against the lethality produced by soman and sarin. Atropine + NaF (15 mg/kg) was effective against tabun, whereas the lower dose of NaF was not. An effect of NaF on organophosphate inhibited acetylcholinesterase could not account for the antidotal action of NaF. NaF had no effect on liver somanase activity but inhibited aliesterase activity. Aliesterase activity in NaF pretreated somanpoisoned mice was significantly (p < 0.05) higher than in those receiving atropine alone. In CBDP-pretreated mice NaF did not significantly attenuate the toxicity of soman. It is hypothesized that the antidotal effect of NaF versus organophosphate poisoning is due to its antidesensitizing action at nicotinic receptors in the neuromuscular junction and/or sympathetic ganglia in addition to the proposed increased hydrolysis of sarin and direct detoxification of tabun.     

Relations Between the Extracellular Concentrations of Choline and Acetylcholine in Rat Striatum

Abstract: Changes in extracellular levels of acetylcholine (ACh) and choline (Ch) in the striatum of rats were examined by in vivo microdialysis after intraperitoneal injections of drugs. A dopamine D₂ antagonist, sulpiride (20 mg/kg), and a muscarinic antagonist, atropine (3.5 mg/kg), increased ACh levels and decreased Ch levels. On the contrary, the D₂ agonist (±)-2-( N -phenylethyl- N -propyl)amino-5-hydroxytetralin (N-434; 5 mg/kg) and an anesthetic, pentobarbital (50 mg/kg), decreased ACh levels and increased Ch levels. Perfusion of 10 µ M hemicholinium-3 (HC-3), a Ch uptake inhibitor, through the striatum induced a complete inhibition of ACh release and increased Ch levels in all drug-treated groups. The degree of relative increase in the level of Ch induced by HC-3 differed among the drug-pretreated groups; compared with the control group, the relative increase was larger in the sulpiride- and atropine-treated groups and smaller in the N-434 and pentobarbital-treated groups. Thus, we demonstrated reciprocal relations between extracellular concentrations of Ch and ACh after treatments by drugs. The data suggest that in the striatum, which is rich in cholinergic innervation, the extracellular Ch concentration is to a large extent determined by activity of the cholinergic transmission reflected in high-affinity choline uptake.