Mechanisms of antidiarrhoeal activity of methanol leaf extract of Combretum hypopilinum diels (combretaceae): Involvement of opioidergic and (α1 and ß)-adrenergic pathways.

ETHNOPHARMACOLOGICAL RELEVANCE: The plant Combretum hypopilinum Diels (Combretaceae) is used in traditional medicine for the treatment of diarrhoea and other diseases in Africa. Previously, the antidiarrhoeal activity of its methanol leaf extract was reported. However, the mechanism(s) responsible for this activity is yet to be evaluated. AIM OF THE STUDY: This study aimed to elucidate the possible mechanism(s) of antidiarrhoeal activity of methanol leaf extract of Combretum hypopilinum (MECH) in mice. MATERIALS AND METHODS: Phytochemical screening and acute toxicity study were conducted according to standard methods. Adult mice were orally (p.o) administered distilled water (10 ml/kg), MECH (1000 mg/kg) and loperamide (5 mg/kg). The probable mechanisms of antidiarrhoeal activity of MECH were investigated following pretreatment with naloxone (2 mg/kg, subcutaneously), prazosin (1 mg/kg, s.c), yohimbine (2 mg/kg, intraperitoneally), propranolol (1 mg/kg, i.p), pilocarpine (1 mg/kg, s.c) and isosorbide dinitrate (150 mg/kg, p.o) 30 min before administration of MECH (1000 mg/kg). The mice were then subjected to castor oil-induced intestinal motility test. RESULTS: The oral median lethal dose (LD50) of MECH was found to be higher than 5000 mg/kg. There were significant (p < 0.05) decrease in the charcoal movement in the mice treated with the MECH (1000 mg/kg) and loperamide (5 mg/kg). The pretreatment of the mice with naloxone, prazosin and propranolol each significantly (p<0.05) reversed the antidiarrhoeal activity produced by MECH. CONCLUSION: The results obtained in this study suggest the probable involvement of opioidergic and (α1 and ß)-adrenergic systems in the antidiarrhoeal activity of the methanol leaf extract of Combretum hypopilinum.

Interaction of aqueous leaf extract of Aegle marmelos (L.) Corr. with cholinergic, serotonergic and adrenergic receptors: an ex vivo study.

OBJECTIVES: The aim was to study interaction of aqueous leaf extract of Aegle marmelos (AM) with cholinergic, serotonergic, and adrenergic receptor systems using appropriate rat tissues-ileum, fundus and tracheal chain, respectively. MATERIALS AND METHODS: Cumulative concentration-response curves (CRC) were constructed at various doses on each tissue for AM and respective standard agonist. The CRC was again plotted in presence and absence of respective standard antagonist to confirm the interaction of receptor system and AM. RESULTS: AM induced concentration-dependent contractions in isolated rat ileum (0.2-6.4 mg/ml) and fundus (0.2-3.2 mg/ml) that were inhibited significantly (P < 0.05) in the presence of atropine (10(-7) M) and ketanserin (10(-6) M), respectively. The relaxant effect, produced by AM (0.2 mg/ml) on carbachol (10(-5) M) precontracted rat tracheal chain, was also inhibited significantly (P < 0.05) by propranolol (1 ng/ml). CONCLUSION: It may be concluded that AM possesses agonistic activity on cholinergic, serotonergic and adrenergic receptors.

Differential effects of non-nicotine tobacco constituent compounds on nicotine self-administration in rats.

Tobacco smoking has been shown to be quite addictive in people. However, nicotine itself is a weak reinforcer compared to other commonly abused drugs, leading speculation that other factors contribute to the high prevalence of tobacco addiction in the human population. In addition to nicotine, there are over 5000 chemical compounds that have been identified in tobacco smoke, and more work is needed to ascertain their potential contributions to tobacco's highly addictive properties, or as potential candidates for smoking cessation treatment. In this study, we examined seven non-nicotine tobacco constituent compounds (anabasine, anatabine, nornicotine, myosmine, harmane, norharmane, and tyramine) for their effects on nicotine self-administration behavior in rats. Young adult female Sprague-Dawley rats were allowed to self-administer nicotine (0.03 mg/kg/50 µl infusion) under a fixed ratio-1 schedule of reinforcement. Each self-administration session lasted 45 min. Doses of each tobacco constituent compound were administered subcutaneously 10 min prior to the start of each session in a repeated measures, counterbalanced order two times. Anabasine displayed a biphasic dose-effect function. Pretreatment with 0.02 mg/kg anabasine resulted in a 25% increase in nicotine self-administration, while 2.0mg/kg of anabasine reduced nicotine infusions per session by over 50%. Pretreatment with 2.0mg/kg anatabine also significantly reduced nicotine self-administration by nearly half. These results suggest that some non-nicotine tobacco constituents may enhance or reduce nicotine's reinforcing properties. Also, depending upon the appropriate dose, some of these compounds may also serve as potential smoking cessation agents.

Plant alkaloids that cause developmental defects through the disruption of cholinergic neurotransmission.

The exposure of a developing embryo or fetus to alkaloids from plants, plant products, or plant extracts has the potential to cause developmental defects in humans and animals. These defects may have multiple causes, but those induced by piperidine and quinolizidine alkaloids arise from the inhibition of fetal movement and are generally referred to as multiple congenital contracture-type deformities. These skeletal deformities include arthrogyrposis, kyposis, lordosis, scoliosis, and torticollis, associated secondary defects, and cleft palate. Structure-function studies have shown that plant alkaloids with a piperidine ring and a minimum of a three-carbon side-chain α to the piperidine nitrogen are teratogenic. Further studies determined that an unsaturation in the piperidine ring, as occurs in gamma coniceine, or anabaseine, enhances the toxic and teratogenic activity, whereas the N-methyl derivatives are less potent. Enantiomers of the piperidine teratogens, coniine, ammodendrine, and anabasine, also exhibit differences in biological activity, as shown in cell culture studies, suggesting variability in the activity due to the optical rotation at the chiral center of these stereoisomers. In this article, we review the molecular mechanism at the nicotinic pharmacophore and biological activities, as it is currently understood, of a group of piperidine and quinolizidine alkaloid teratogens that impart a series of flexure-type skeletal defects and cleft palate in animals.

On the action and mechanism of withaferin-A from Withania somnifera, a novel and potent melanin dispersing agent in frog melanophores.

The present work was carried out to determine the effects of lyophilized root extracts of Withania somnifera along with pure withaferin-A, on the isolated skin melanophores of frog, Rana tigerina which are disguised type of smooth muscle cells and offer excellent in vitro opportunities for studying the effects of pharmacological and pharmaceutical agents. The lyophilized extract of W. somnifera and its active ingredient withaferin-A induced powerful dose-dependent physiologically significant melanin dispersal effects in the isolated skin melanophores of R. tigerina, which were completely blocked by atropine as well as hyoscine. The per se melanin dispersal effects of lyophilized extracts of W. somnifera and its active ingredient withaferin-A got highly potentiated by neostigmine. It appears that the melanin dispersal effects of the extracts of W. somnifera and withaferin-A is mediated by cholino-muscarinic like receptors having similar properties.

Pharmacological mechanism responsible for the Atractylodes japonica-induced distal colonic contraction in rats.

BACKGROUND AND AIM: Atractylodes japonica Koidz (Compositae) has been commonly used to treat the gastrointestinal (GI) disorders in Korean traditional medicine, but its pharmacological roles in the regulation of GI motility have not been clarified yet. METHODS: Atractylodes japonica was sequentially partitioned with MeOH, n-hexane, CHCl(3), EtOAc and n-BuOH saturated with H(2)O, and the effects of Atractylodes japonica extracts on the spontaneous contractility of GI muscle strips prepared from rats were measured. RESULTS: Among five different fractionations, EtOAc extracts of Atractylodes japonica (AJEA) dose-dependently increased the low frequency contraction of distal colon longitudinal muscles (DCLM), and the ED(50) values were revealed to be 1.71×10(-9) g/ml. Among GI tracts, a prominent contractile response to AJEA was observed only in the DCLM. The contractile patterns produced by AJEA remarkably differed from those caused by acetylcholine and 5-HT. 4-DAMP and methoctramine at 0.5 µM significantly blocked the AJEA (1.0 µg/ml)-induced contraction of DCLM, but ondansetron, GR113808 and methysergide at 1.0 µM in combination did not change the AJEA-induced DCLM contractions. Acetylethylcholine mustard (5.0 µM) significantly diminished the AJEA-induced DCLM contractions, whereas p-chlorophenyl alanine (1.0 µM) did not affect the stimulatory effects of AJEA on the DCLM contractions. CONCLUSION: The present results suggest that AJEA may specifically act on the DCLM among GI smooth muscles, and AJEA-induced DCLM contraction is likely mediated, at least, by activation of ChAT and acetylcholinergic muscarinic receptors.

Hexane extract of Poncirus trifoliata (L.) Raf. stimulates the motility of rat distal colon.

AIM OF THE STUDY: Poncirus trifoliata (L.) Raf. (Rutaceae, PT) has been commonly used for treating gastrointestinal (GI) disorders in Korean traditional medicine, but its pharmacological roles in the regulation of colonic motility have not been clarified. This study investigated the regulatory effects of PT on the colonic motility. MATERIALS AND METHODS: Immature fruits of PT were sequentially partitioned with MeOH, n-hexane, CHCl(3), EtOAc, n-BuOH and H(2)O, and the effects of PT extracts on the contractility of colonic strips and colonic luminal transit in rats were measured in vitro and in vivo, respectively. RESULTS: Among six different extracts, only hexane extract of PT (PTHE) dose-dependently increased the low frequency contraction of longitudinal muscle in distal colonic strips, and the ED(50) value was revealed to be 0.71 microg/ml. The contractile patterns induced by PTHE were remarkably different from those caused by acetylcholine (ACh) and serotonin (5-HT). The stimulatory effects of PTHE on the whole distal colonic strips were more prominent than on the mucosa/submucosa-denuded segments. The M(2) receptor-preferring, methoctramine (0.5 microM), and M(3) receptor-preferring antagonist, 4-DAMP (0.5 microM) significantly blocked the PTHE (1 microg/ml)-induced contraction of distal colon longitudinal muscles, whereas the 5-HT receptor antagonists (1.0 microM, alone or in combination) selective for 5-HT(3) (ondansetron), 5-HT(4) (GR113808) and 5-HT(1, 2, 5-7) (methysergide) receptors did not change the PTHE (1 microg/ml)-induced contractility of distal colon longitudinal muscles. SNAP (0.1mM), a NO donor, enhanced the stimulatory effects of PTHE on the longitudinal muscle of distal colon, but l-NAME (0.1mM), a NO synthesis inhibitor, had no effects. PTHE (10-100mg/kg) caused a dose-dependent increase of colonic luminal transit. CONCLUSIONS: Collectively, these findings suggest that PTHE specifically acts on the longitudinal muscle of distal colon in rats, and these stimulatory effects are likely mediated, at least, by activation of acetylcholinergic M(2) and M(3) receptors.

Filicene obtained from Adiantum cuneatum interacts with the cholinergic, dopaminergic, glutamatergic, GABAergic, and tachykinergic systems to exert antinociceptive effect in mice.

In the present study, we describe the antinociceptive effect of filicene, a triterpene isolated from Adiantum cuneatum (Adiantaceae) leaves, in several models of pain in mice. When evaluated against acetic acid-induced abdominal constrictions, filicene (10, 30 and 60 mg/kg, i.p.) produced dose-related inhibition of the number of constrictions, being several times more potent [ID(50)=9.17 (6.27-13.18) mg/kg] than acetaminophen [ID(50)=18.8 (15.7-22.6) mg/kg], diclofenac [ID(50)=12.1(9.40-15.6) mg/kg] and acetylsalicylic acid [ID(50)=24.0(13.1-43.8) mg/kg] in the same doses as those used for the standard drugs. Filicene also produced dose-related inhibition of the pain caused by capsaicin and glutamate, with mean ID(50) values of 11.7 (8.51-16.0) mg/kg and <10 mg/kg, respectively. Its antinociceptive action was significantly reversed by atropine, haloperidol, GABA(A) and GABA(B) antagonists (bicuculline and phaclofen, respectively), but was not affected by L-arginine-nitric oxide, serotonin, adrenergic and the opioid systems. Together, these results indicate that the mechanisms involved in its action are not completely understood, but seem to involve interaction with the cholinergic, dopaminergic, glutamatergic, GABAergic and tachykinergic systems.

Cholinergic properties of soy.

OBJECTIVES: Soybeans have been shown to have numerous health benefits, but the underlying mechanisms are poorly understood. The aim of this study was to characterize some pharmacologic properties of active substances in aqueous soy extract. METHODS: The pharmacologic actions of the extract were tested by measuring mechanical activity of isolated guinea-pig ileum in an organ bath. RESULTS: The ileum contracted in response to soy extract in a concentration-dependent manner. This response was unaffected by the nerve blocker tetrodotoxin (10(-6) M) but was completely inhibited by atropine (10(-9) M), indicating an action via muscarinic receptors on the muscle. In the presence of the M(3) muscarinic antagonist 1,1-dimethyl-4-diphenylacetoxypiperidinium iodide and to a lesser extent in the presence of the M(2) muscarinic antagonist 11-([2-[(diethylamino)methyl]-1-piperidinyl]acetyl)-5,11-dihydro-6H-pyrido[2,3-b][1,4]benzodiazepine-6-one, the response was decreased. When acetylcholine (ACh) esterase inhibitors were added to the medium before the addition of soy extract, the response to the extract was potentiated. Preincubation of the extract with exogenous ACh esterase reduced its activity. The response to choline, ACh, and phosphorylcholine was also tested, and none of these substances accurately replicated the response to soy extract. However, some qualitative similarities were observed between the effect of choline and ACh to that of the extract. CONCLUSION: These results indicate the presence of an ACh-like substance in soy. Due to the abundance and importance of muscarinic receptors, the presence of a cholinergic substance in soy could have numerous implications. The role of this substance in the beneficial effect of soy on various body systems merits further investigation.

A role for acetylcholine receptors in their own aggregation on muscle cells.

Both neurotrophic factors and activity regulate synaptogenesis. At neuromuscular synapses, the neural factor agrin released from motor neuron terminals stimulates postsynaptic specialization by way of the muscle specific kinase MuSK. In addition, activity through acetylcholine receptors (AChRs) has been implicated in the stabilization of pre- and postsynaptic contacts on muscle at various stages of development. We show here that activation of AChRs with specific concentrations of nicotine is sufficient to induce AChR aggregation and that this induction requires the function of L-type calcium channels (L-CaChs). Furthermore, AChR function is required for agrin induced AChR aggregation in C2 muscle cells. The same concentrations of nicotine did not induce observable tyrosine phosphorylation on either MuSK or the AChR beta subunit, suggesting significant differences between the mechanisms of agrin and activity induced aggregation. The AChR/L-CaCh pathway provides a mechanism by which neuromuscular signal transmission can act in concert with the agrin-MuSK signaling cascade to regulate NMJ formation.

Increase in cochlear microphonic potential after toluene administration.

Human and animal studies have shown that toluene can cause hearing loss. In the rat, the outer hair cells are first disrupted by the ototoxicant. Because of their particular sensitivity to toluene, the cochlear microphonic potential (CMP) was used for monitoring the cochlea activity of anesthetized rats exposed to both noise (band noise centered at 4 kHz) and toluene. In the present experiment, the conditions were specifically designed to study the toluene effects on CMP and not those of its metabolites. To this end, 100-microL injections of a vehicle containing different concentrations of solvent were made into the carotid artery connected to the tested cochlea. Interestingly, an injection of 116.2-mM toluene dramatically increased in the CMP amplitude (approximately 4 dB) in response to an 85-dB SPL noise. Moreover, the rise in CMP magnitude was intensity dependent at this concentration suggesting that toluene could inhibit the auditory efferent system involved in the inner-ear or/and middle-ear acoustic reflexes. Because acetylcholine is the neurotransmitter mediated by the auditory efferent bundles, injections of antagonists of cholinergic receptors (AchRs) such as atropine, 4-diphenylacetoxy-N-methylpiperidine-methiodide (mAchR antagonist) and dihydro-beta-erythroidine (nAchR antagonist) were also tested in this investigation. They all provoked rises in CMP having amplitudes as large as those obtained with toluene. The results showed for the first time in an in vivo study that toluene mimics the effects of AchR antagonists. It is likely that toluene might modify the response of protective acoustic reflexes.

The psychopharmacology of European herbs with cognition-enhancing properties.

Extensive research suggests that a number of plant-derived chemicals and traditional Oriental herbal remedies possess cognition-enhancing properties. Widely used current treatments for dementia include extracts of Ginkgo biloba and several alkaloidal, and therefore toxic, plant-derived cholinergic agents. Several non-toxic, European herbal species have pan-cultural traditions as treatments for cognitive deficits, including those associated with ageing. To date they have not received research interest commensurate with their potential utility. Particularly promising candidate species include sage (Salvia lavandulaefolia/officinalis), Lemon balm (Melissa officinalis) and rosemary (Rosmarinus officinalis). In the case of sage, extracts possess anti-oxidant, estrogenic, and anti-inflammatory properties, and specifically inhibit butyryl- and acetyl-cholinesterase. Acute administration has also been found to reliably improve mnemonic performance in healthy young and elderly cohorts, whilst a chronic regime has been shown to attenuate cognitive declines in sufferers from Alzheimer's disease. In the case of Melissa officinalis, extracts have, most notably, been shown to bind directly to both nicotinic and muscarinic receptors in human brain tissue. This property has been shown to vary with extraction method and strain. Robust anxiolytic effects have also been demonstrated following acute administration to healthy humans, with mnemonic enhancement restricted to an extract with high cholinergic binding properties. Chronic regimes of aromatherapy and essential oil respectively have also been shown to reduce agitation and attenuate cognitive declines in sufferers from dementia. Given the side effect profile of prescribed cholinesterase inhibitors, and a current lack of a well tolerated nicotinic receptor agonist, these herbal treatments may well provide effective and well-tolerated treatments for dementia, either alone, in combination, or as an adjunct to conventional treatments.

Tardive dyskinesia and essential fatty acids.

Tardive dyskinesia (TD) is a movement disorder described in individuals who have been treated with anti-dopaminergic agents. The pathophysiology of this condition remains to be fully elucidated. Several mechanisms like dopaminergic supersensitivity, dysfunction of striatonigral, GABAergic neurons and disturbed balance between dopaminergic and cholinergic systems have been described. Essential fatty acids (EFAs) are important components of neuronal membrane and the EFA content of these membranes can significantly influence neuronal functioning. Lower levels of EFAs have been reported in red blood cells (RBC) and plasma of individuals with moderate to severe TD. Supplementation with EFAs (omega-3 and omega-6 and ethyl-EPA) have been tried to alleviate TD in open and double-blind clinical trials and in some animal models of TD. In addition, antioxidants (Vitamin E) and melatonin have been tried. However, smaller numbers of patients and shortened length of clinical studies make it difficult to draw any definitive conclusions. Large multi-centre studies with sound methodology of both EFAs and antioxidants are needed.

Effects of Salvia officinalis L. (sage) leaves on memory retention and its interaction with the cholinergic system in rats.

OBJECTIVE: The leaves of sage (Salvia officinalis L., Lamiaceae) are reported to have a wide range of biological activities, such as anti-bacterial, fungistatic, virustatic, astringent, eupeptic and anti-hydrotic effects. To determine the mnemogenic effect of sage leaves, we investigated the effects of ethanolic extract of sage leaves and its interaction with cholinergic system on memory retention of passive avoidance learning in rats. METHODS: Post-training intracerebroventricular (i.c.v.) injections were carried out in all the experiments except ethanolic extract (i.p. intraperitoneally). RESULTS: Administration of ethanolic extract (50 mg/kg), pilocarpine (0.5 and 1 mg/rat), the muscarinic cholinoceptor agonist, and nicotine (0.1 and 1 microg/rat) increased, while mecamylamine (1, 5 microg/rat), the muscarinic cholinoceptor antagonist, and mecamylamine (0.01 and 0.1 microg/rat), the nicotine cholinoceptor antagonist decreased memory retention in rats. Activation of muscarinic cholinoceptors by pilocarpine potentiated the response of ethanolic extract. Also, pharmacological blockade of scopolamine attenuated potentiating effect of ethanolic extract. Activation of nicotinic cholinoceptor by nicotine potentiated the response of ethanolic extract. Blockade of nicotinic cholinoceptor by mecamylamine attenuated the response of ethanolic extract. CONCLUSION: It is concluded that the ethanolic extract of salvia officinalis potentiated memory retention and also it has an interaction with muscarinic and nicotinic cholinergic systems that is involved in the memory retention process.

Analgesic substances derived from natural products (natureceuticals).

From the first recorded accounts, over 7000 years ago, various forms of natural products have been utilized to treat pain disorders. Prototypical examples of such natural products are the opium poppy (Papaver soniferum) and the bark of the willow tree (Salix spp.). It was not until the 19th century when individual compounds were isolated from these substances and were determined to posses the desired effects. The known sources of these substances have been thoroughly investigated. Over the last several decades, more analgesic substances have been purified from natural products resulting in novel structural classes and mechanisms of actions. Plants and other natural products described in historical ethnobotanical and ethnopharmacological literature have become of more recent interest in drug discovery efforts. These manuscripts and reports are being utilized to aid in the identification of natural products that have been historically employed in the alleviation of pain. A large factor that has highlighted the importance of discovering novel compounds to treat pain has been in the fundamental understanding of the complex mechanisms of pain transmission in the nervous system. Nociceptive processing involves many receptor classes, enzymes and signaling pathways. The identification of novel classes of compounds from natural sources may lead to advancing the understanding of these underlying pharmacological mechanisms. With the potential of uncovering new compounds with idealistic pharmacological profiles (i.e., no side effects, no addictive potential), natural products still hold great promise for the future of drug discovery especially in the treatment of pain disorders and potentially drug addictions.

Increased calcium influx through acetylcholine receptors in dunce neurons.

Calcium homeostasis was studied in dunce, a Drosophila mutant that is defective in learning and memory. Fura 2-AM fluorescence photometry was used to measure the intracellular calcium concentration in wild type and dunce cleavage-arrested neurons under resting conditions and in response to neurotransmitters. After acetylcholine application, the peak [Ca2+]i was greater in dunce (693 +/- 125 nM) than in wild type neurons (464 +/- 154 nM), but half decay time was shorter in dunce (66 +/- 15 s) than in wild type neurons (104 +/- 40 s). In contrast, the application of glutamate, NMDA, dopamine, and serotonin had no effect on [Ca2+]i. These results indicate that calcium influx through acetylcholine receptors is increased in dunce, compared to wild type neurons. The results also suggest that calcium extrusion to the outside and/or calcium buffering are enhanced in dunce, compared to wild type neurons. This disturbance in the homeostasis of cytosolic calcium concentration in dunce may be implicated in defective associative learning in Drosophila, and may play a role in acute and chronic neurodegenerative disorders in the mammalian brain.

[The effect of TWP on the reactivity of AChR on the end-plate membrane of frog sartorius].

OBJECTIVE: To study the effect of Tripterygium Wilfordii Polyglycosidium (TWP) on the reactivity of n-Acetylcholine receptor (nAChR) on the end plate membrane. METHODS: Using the microionophoretic method, we applied the exogenous acetylcholine chloride (AChCl) to the superficial end-plates of the isolated nonuniform stretched frog sartorius, and acetylcholine potential (AChP) recorded was taken as an indicator of the reactivity of the nAChR in the end plate. RESULTS: 1. After the addition of TWP, the apparent change of AChP was recorded at 20 min in the 20 mg/L group, and at 10 min in the 40 mg/L and 60 mg/L groups respectively. 2. Within the 20 mg/L and 40 mg/L TWP groups, the change in amplitude of AChP showed significant difference with the time (P < 0.05), the greatest being at 60 min. 3. In the 60 mg/L TWP group, action potential was recorded at 40 min, 60 min and 80 min. 4. There was significant difference in the percentage of AChP amplitude change between the three concentration groups (P < 0.05), and the highest percentage of change appeared in the 60 mg/L group. CONCLUSION: TWP can increase the reactivity of nAChR in the end plate membrane, and there exist an apparent concentration-effect relationship and a certain time-effect relationship.

[Cholinergic mechanisms in the pathogenesis of genetically-caused absence epilepsy]. / Kholinergicheskie mekhanizmy v patogeneze geneticheski obuslovlennoi absansnoi épilepsii.

Frontoparietal cortex and the thalamocortical circuit comprising reticular thalamic nucleus (RTN) and relay nuclei of the ventrolateral thalamus (VLT) are critical structures in the generation of spike-wave discharges (SWD) during absence seizures. The activity of these nuclei is under the control of the ascending cholinergic projections of nucleus basalis of Meynert. The aim of our study is to make an attempt to change the pattern of SWD in WAG/Rij rats by injecting of cholinotoxine AF64A to the area of RTN. Spontaneous SWD were registered in cortex of WAG/Rij rats with genetically determined absences. The spectral content of SWD was analyzed by means of the Fast Fourier Transformation (FFT) procedure. Unilateral injections of AF64A (1 nmol) to RTN led the decrease in duration and number of SWD comparing to the basal EEG recordings 2 days after the lesion. The FFT analysis showed the disappearance of 17-18 Hz spike on the side of the lesion compared with the intact side. The immunohistochemical study for acetylcholinetransferase (ChaT)-containing neurons showed the loss of ChaT-positive cells in the nucleus basalis area on the side of the lesion. The removal of cholinergic afferentation of RTN and cortex from nucleus basalis inhibits the SWD developing most likely due to the decrease of cortical excitability. Moreover, possibly cholinergic transmission is involved in the transforation of the synchronized phenomena (SWD) to another with close mechanism of generation.

Cholinergic receptor blockade in prefrontal cortex and lesions of the nucleus basalis: implications for allocentric and egocentric spatial memory in rats.

In this study we have examined the involvement of the prefrontal cortex (PFC) along with the Nucleus basalis magnocellularis (NBM) in two types of spatial navigation tasks. We evaluated the effects of excitotoxic (ibotenate-induced) lesions of the NBM in an allocentric and an egocentric task in the Morris water maze, using sham operations for a comparison. In both cases we also assessed the effects of local cholinergic receptor blockade in the PFC by infusing the muscarinic receptor antagonist scopolamine (4 or 20 microg). Anatomically, the results obtained showed that this lesion produced a profound loss of acetylcholinesterase (AChE) positive cells in the NBM, and a loss of AChE positive fibres in most of the neocortex, but hardly in the medial PFC. Behaviourally, such lesions led to a severe impairment in the allocentric task. Intraprefrontal infusions of scopolamine led to a short-lasting impairment in task performance when the high dose was used. In the second experiment, using the same surgical manipulations, we examined the performance in the egocentric task. Like in the allocentric task animals with NBM lesions were also impaired, but with continued training they acquired a level of performance similar to the sham-operated ones. This time, infusions of scopolamine in the medial PFC led to a severe disruption of performance in both groups of animals. We conclude that acetylcholine in the medial PFC is important for egocentric but not allocentric spatial memory, whereas the NBM is involved in the learning of both tasks, be it to a different degree.

Anti-inflammatory and spasmolytic activity of extracts from Droserae herba.

An ethanolic extract of Drosera madagascariensis inhibited human neutrophil elastase with an IC50 of 9.4 microg/ml. The naphthoquinones present in the extract were not responsible for this effect, but flavonoids like quercetin (IC50 0.8 microg/ml), hyperoside (IC50 0.15 microg/ml) and isoquercitrin (IC50 0.7 microg/ml) contributed to inhibition of the enzyme. In guinea-pig ileum the extract (0.5-1 mg/ml) induced a spasmolytic effect via affecting cholinergic M3 receptors and histamine H1 receptors, respectively. At contractile prostanoid receptors of guinea-pig trachea the Drosera extract was not effective.