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B Costall

Publications and source records attributed to B Costall.

At least 55 records · Page 3Linked to original sources

The profiles of interaction of yohimbine with anxiolytic and putative anxiolytic agents to modify 5-HT release in the frontal cortex of freely-moving rats.

1. The interaction of yohimbine with anxiolytic and putative anxiolytic agents to modify 5-hydroxytryptamine (5-HT) release in the frontal cortex of the freely-moving rat was assessed using the microdialysis technique. 2. The alpha 2-adrenoceptor antagonist, yohimbine (5.0 mg kg-1, i.p.) increased maximally the extracellular levels of 5-HT in the rat frontal cortex by approximately 230% of the basal levels. 3. The alpha 2-adrenoceptor agonist, clonidine (30-100 micrograms kg-1, i.p.) decreased dose-dependently the extracellular levels of 5-HT in the rat frontal cortex by approximately 0-60% of the basal levels. A 5 min pretreatment with clonidine (50 micrograms kg-1, i.p.) prevented the yohimbine-induced increase in the extracellular 5-HT levels. 4. The benzodiazepine receptor agonist, diazepam (2.5 mg kg-1, i.p.) and the 5-HT3 receptor antagonist, ondansetron (100 micrograms kg-1, i.p.) (5 min pretreatment) completely prevented the yohimbine (5.0 mg kg-1, i.p.)-induced increases in the extracellular levels of 5-HT. The 5-HT1A receptor agonist, 8-OH-DPAT (0.32 mg kg-1, s.c.) partially antagonized the yohimbine response. 5. A 5 min pretreatment with the 5-HT3/5-HT4 receptor ligand R(+)-zacopride (10 micrograms kg-1, i.p.) reversed the yohimbine (5.0 mg kg-1, i.p.)-induced increase in the extracellular levels of 5-HT to approximately 30% below the basal levels. A 5 min pretreatment with S(-)-zacopride (100 micrograms kg-1, i.p.) failed to modify the response to yohimbine. 6. The present study provides evidence of the ability of the anxiogenic agent, yohimbine, to increase the activity of the central 5-hydroxytryptaminergic system and the ability of clonidine and various anxiolytic and putative anxiolytic agents to prevent the yohimbine response.

8-Hydroxy-2-(di-n-propylamino)tetralin↗

5-HT4 receptor mediated facilitation of the emptying phase of the peristaltic reflex in the guinea-pig isolated ileum.

1. The influence of 5-hydroxytryptamine (5-HT) receptor agonists and antagonists on the emptying phase (circular muscle contraction) of the peristaltic reflex was investigated in the guinea-pig isolated ileum. 2. The effect of drug application to the serosal surface was measured as the changes in threshold pressure required to trigger the peristaltic reflex and the interval between the peristaltic strokes. A facilitation or inhibition of peristalsis was defined as a reduction or increase in threshold pressure respectively. 3. Peristalsis was not modified by the inclusion of methysergide (1 microM) and/or ondansetron (2 microM) in the bathing medium. 5-HT (0.1-1.0 microM) caused a facilitation of the peristaltic reflex; the response curve to 5-HT was not altered by the presence of methysergide (1 microM) and ondansetron (2 microM). 4. In the presence of methysergide (1 microM) plus ondansetron (2 microM), 5-HT (7.36 +/- 0.06), 5-methoxytryptamine (7.01 +/- 0.17), 5-carboxamidotryptamine (5.43 +/- 0.06), renzapride (6.09 +/- 0.17), (S)-zacopride (5.99 +/- 0.11), (R)-zacopride (5.61 +/- 0.13) and metoclopramide (4.8 +/- 0.65) caused a concentration-related facilitation of the peristaltic reflex, the pEC50 values (mean +/- s.e.mean) being shown in parentheses. 2-Methyl-5-HT was ineffective up to 10 microM. 5. The administration of SDZ 205-557 (1 microM) alone failed to modify the peristaltic reflex, but caused a parallel dextral shift in the concentration-effect curve to 5-HT (apparent pKB 7.38 +/- 0.30). It failed to modify the effect of acetylcholine to enhance the peristaltic reflex. 6. It is concluded that the rank order of potency of the 5-HT agonists from the indole and substituted benzamide series to facilitate the emptying phase of the peristaltic reflex in the guinea-pig ileum closely correlates with their published actions as 5-HT4 agonists in other systems. An agonist action on the 5-HT4 receptor is also supported by the potency of the 5-HT3/5-HT4 antagonist SDZ 205-557 (but not the 5-HT3 antagonist ondansetron) to inhibit the effects of 5-HT.

4-Aminobenzoic Acid↗

The effects of 5-HT3 receptor antagonists in models of dependency and withdrawal.

Pharmacological manipulations to enhance 5-HT synthesis and release have been reported to reduce alcohol intake. However, recent evidence indicates that 5-HT3 receptor antagonists may also exert a similar effect in a number of species. This report reviews the existing data which implicates a central role for 5-HT3 receptors in the control of psychoactive substance abuse.

Alcohol Drinking↗

The interaction of R(+)- and S(-)-zacopride with PCPA to modify rodent aversive behaviour.

The interaction of R(+)- and S(-)zacopride (0.00001-10 mg/kg i.p.) with parachlorophenylalanine (PCPA, 3 day treatment 100 mg/kg i.p.) to modify behaviour in an aversive situation was investigated in the mouse black and white test box and rat social interaction test. R(+)-Zacopride (but not S(-)zacopride) and PCPA had an anxiolytic profile of action to reduce aversive responding in both species. Their established anxiolytic profiles were abolished by a subsequent treatment with S(-)zacopride. In contrast, S(-)-zacopride was less or ineffective if administered simultaneously with R(+)-zacopride. A co-treatment of PCPA with R(+)-zacopride also inhibited the anxiolytic profiles observed to the individual treatments. It is concluded that there is a complex interaction between the isomers of zacopride to modify responding to an aversive situation that is dependent on the temporal sequence of drug administration, and which may be modified by changes in basal 5-hydroxytryptamine (5-HT) tone and agonist, partial agonist and antagonist effects at the 5-HT3 receptor.

Animals↗

Profiles of interaction of R(+)/S(-)-zacopride and anxiolytic agents in a mouse model.

The mouse black and white test box was used to measure changes in behaviour in an aversive situation where the administration of R(+)-zacopride (but not S(-)-zacopride) alone decreased aversive responding to the white area. A similar anxiolytic profile of action was observed using parachlorophenylalanine (PCPA), whose effects were antagonised by a co-treatment with R(+)-zacopride and reversed by S(-)-zacopride to an exacerbation of the aversive response. An anxiolytic profile of action was also observed using ondansetron, granisetron, chlordiazepoxide, diazepam, ritanserin, 8-OH-DPAT (8-hydroxy-2-(di-n-propylamino)tetralin), E4424 (2-[4-[4-(4-chloro-l-pyrazoyl)butyl]-l-piperazinyl]-pyrimidine), umepsirone, DuP753 (2-n-butyl-4-chloro-5-hydroxy-methyl-1-[2(1H-tetrazol-5-yl) biphenyl-4-yl)methyl)]-imidazole), SQ29,852 ((S)-1-[6-amino-2[hydroxy)(4-phenyl-butyl)phosphinyl]-oxy)-1- nexy]-2-proline), devazepide and guanfacine, and this was retained following co-treatment with PCPA. The anxiolytic profile of action of PCPA was also retained following co-treatment with renzapride which when administered alone failed to modify behaviour. However, the ability of chlordiazepoxide, diazepam, ondansetron and E4424 (but not devazepide, DuP753 or SQ29,852) to reduce aversive responding was inhibited by co-treatment with R(+) and/or S(-)-zacopride. It is concluded that the reduction in aversive responding caused by pharmacological manipulation at the benzodiazepine, 5-HT receptor subtypes 5-HT1A, 5-HT1C/5-HT2 and 5-HT3 (but not at the cholecystokin CCKA or angiotensin receptors or inhibition of angiotensin converting enzyme) can be inhibited by R(+) and S(-)-zacopride. The data is discussed in terms of zacopride having an agonist or partial agonist effect at the 5-HT3 receptor.

Animals↗

The distribution of 5-HT3 recognition sites in the marmoset brain.

The distribution of the binding of [3H]GR65630 (0.2 nM) to putative 5-HT3 recognition sites in the brain of the common marmoset was assessed using autoradiography. Specific binding was heterogeneously distributed with the highest densities found in discrete nuclei of the lower medulla (nucleus tractus solitarii, dorsal motor nucleus of the vagus nerve, nucleus of spinal trigeminal nerve tract and the area postrema). In forebrain areas, relatively high binding densities were located in the medial habenula nucleus and the hippocampus (CA3, CA4 and fascia dentata). Low levels of specific binding in the rest of the forebrain hindered quantification.

Animals↗

Pharmacological comparison of the rat and guinea-pig cortical high affinity 5-hydroxytryptamine uptake system.

The pharmacological characteristics of the high affinity [3H]5-hydroxytryptamine ([3H]5-HT) uptake system were investigated in the cerebral cortex of the rat and guinea-pig. In crude cortical synaptosomal preparations from the rat and guinea-pig, [3H]5-HT accumulated with high affinity (Km, 72 +/- 12 and 57 +/- 14 nM for rat and guinea-pig cortical synaptosomal preparation, respectively, mean +/- SEM, N = 5) and with a comparable maximum activity (Vmax, 1.22 +/- 0.21 and 0.90 +/- 0.19 pmol/min/mg protein for rat and guinea-pig cortical synaptosomal preparation, respectively, mean +/- SEM, N = 5). Competition studies employing a range of structurally diverse competing compounds showed that the [3H]5-HT uptake was pharmacologically similar in both preparations. However, citalopram possessed approximately 10-fold weaker affinity to prevent [3H]5-HT uptake in the guinea-pig preparation when compared to the rat and all of the tricyclic antidepressants assessed in the present studies (amitriptyline, nortriptyline, desipramine and imipramine) displayed higher affinity in the guinea-pig preparation when compared to the rat. It is concluded that the high affinity 5-HT uptake systems in the rat and guinea-pig cortex are similar but may not be identical.

Amitriptyline↗

Pharmacological comparison of the sigma recognition site labelled by [3H]haloperidol in human and rat cerebellum.

The radioligand binding characteristics of [3H]haloperidol (in the presence of spiperone, 25 nmolL-1) were investigated in rat and human cerebellar membranes. In both rat and human cerebellar membrane preparations saturation studies with [3H]haloperidol (non-specific binding defined by pentazocine, 10 mumolsL-1) demonstrated high affinity saturable specific binding to a homogenous population of binding sites (rat, Bmax 6693 +/- 1242 fmol mg-1 protein, pKD 8.33 +/- 0.08; human, Bmax 2550 +/- 437 fmol mg-1 protein, pKD 8.59 +/- 0.11; mean +/- SEM, n = 3-6). Competition studies employing a wide range of structurally diverse competing compounds displayed that the [3H]haloperidol binding site was pharmacologically similar in both preparations and comparable to sigma recognition sites previously identified in various tissues originating from different species. In addition, with reference to the potential subtypes of sigma recognition sites, the labelling of these sites by low nanomolar concentrations of [3H]haloperidol provides evidence that they belong to the sigma-1 recognition site subtype. The present findings suggest that the pharmacology of the rat and human cerebellar sigma recognition site are directly comparable and provides further supporting evidence towards the use of [3H]haloperidol radioligand binding studies in the rat to detect sigma receptor ligands with potential therapeutic activity.

Animals↗

Toxic effects of solstitialin A 13-acetate and cynaropicrin from Centaurea solstitialis L. (Asteraceae) in cell cultures of foetal rat brain.

Extracts of the aerial parts of the yellow star thistle (Centaurea solstitialis L.) were prepared using petroleum ether, chloroform and methanol and toxicity assessed in primary cell cultures of striatum, frontal cortex and mesencephalon, containing the substantia nigra or raphe nucleus from the brain of the foetal rat. Chloroform extracts significantly reduced the percentage of live cells whereas the petroleum ether extract was inactive. The ability of the methanol extract to reduce the percentage of live cells could not be distinguished from the effects of the vehicle controls for methanol. Subsequently, the plant material was extracted with dichloromethane and 10 fractions were obtained by column chromatography. Fractions 5, 6, 7 and 8 caused concentration-dependent cell death in the culture of substantia nigra, the other fractions were not toxic at the concentrations used. In further studies, solstitialin A was isolated from fraction 9, solstitialin A 13-acetate from fraction 6 and solstitialin A-3 acetate and cynaropicrin from fraction 7. Solstitialin A 13-acetate and cynaropicrin were toxic to cultures of substantia nigra cells. It is concluded that, of the compounds identified, solstitialin A 13-acetate and cynaropicrin have toxic potential in cell cultures, containing cells from the substantia nigra of the rat, the specificity of action to cells of the substantia nigra remains to be shown, and that a toxic action in the midbrain may contribute to the nigro-pallidal encephalomalacia, caused by the ingestion of the yellow star thistle by horses.

Animals↗

Ondansetron and arecoline prevent scopolamine-induced cognitive deficits in the marmoset.

The cognitive-enhancing potential of the 5-hydroxytryptamine (5-HT) selective 5-HT3 receptor antagonist, ondansetron, was investigated in a model of cognitive impairment induced by the muscarinic receptor antagonist, scopolamine. For this purpose, marmosets were trained in an object discrimination task utilizing the Wisconsin General Test Apparatus. Administration of scopolamine (0.01-0.04 mg/kg, SC) caused a dose-dependent impairment in the acquisition of the object discrimination task in that marmosets required more trials to reach criterion, made more errors, and took longer to choose the objects. Administration of arecoline (0.06-0.1 mg/kg, SC) or 1,2,3,9-tetrahydro-9-methyl-3-[(2-methyl-1H-imidazol- 1-yl)methyl]-4H-carbazol-4-one,HCl.2H2O (ondansetron) (0.1-1 micrograms/kg, SC) prevented the scopolamine-induced impairment in task acquisition in that the performance of marmosets was indistinguishable from that of saline-treated animals and was significantly better than that following scopolamine/saline. From these studies, we conclude that ondansetron prevents impairment in the cognitive performance of marmosets induced by administration of scopolamine.

Animals↗

Behavioural effects of anxiogenic agents in the common marmoset.

The effects of the anxiogenic agents FG7142, caffeine, pentylenetetrazole, and amphetamine were assessed in two anxiety situations in the marmoset, first in an "anxiogenic" test based on the animal's response to a human observer standing in front of the home cage and second in a low-anxiety situation where animals behaviour was videotaped in the absence of the observer. In response to the human observer, the anxiolytic agent diazepam (0.1-2.5 mg/kg, SC) was shown to reduce the intensity of behaviours such as postures, while increasing time spent on the cage front. In this test, with the exception of amphetamine, which only modified responding at stereotypic doses, the anxiogenic agents failed to modify marmoset behaviour. In contrast, in the low-anxiety filming protocol the anxiogenic agents consistently reduced measures of locomotor activity while increasing the amount of time animals spent in the nest box. It is suggested that the low-anxiety protocol may be useful to evaluate drug-induced anxiogenesis and in studies of withdrawal from chronic anxiolytic treatment or drugs of abuse.

Amphetamine↗

Anxiolytic-like actions of anpirtoline in a mouse light-dark aversion paradigm.

The anxiolytic-like potential of anpirtoline was assessed in a mouse light/dark aversion test. Anpirtoline (1.0 ng kg(-1)-1.0 micrograms kg-1 i.p.) reduced the aversive responding of mice. This was detected as an increase in the latency to locate the non-aversive compartment and by decreases in the percentage of the time spent in the dark compartment, and the numbers of rears and line crossings in the dark compartment. In radioligand binding studies anpirtoline displayed submicromolar affinity for 5-HT1A, 5-HT1B and 5-HT3 receptor recognition sites (Ki = 151, 28 and 30 nM, respectively) and more modest affinity for 5-HT2 receptor recognition sites (Ki = 1.48 microM). It is concluded that anpirtoline has a unique spectrum of affinity for 5-HT receptor subtypes, its interaction with which may account for its anxiolytic-like activity.

Animals↗

Angiotensin-converting enzyme inhibition, angiotensin, and cognition.

In these studies, we have investigated possible cognition-enhancing effects of angiotensin-converting enzyme (ACE) inhibition, and putative neurochemical correlates for these actions. In a mouse habituation model, ACE inhibitors improved basal performance and antagonized scopolamine-induced deficits. The performance of aged mice and those with lesions of the nucleus basalis was also improved. ACE inhibition also improved scopolamine-impaired performance of rats in a swim-maze model. Neurochemical studies showed that a low dose (10 micrograms/kg i.p.) of ceranapril caused significant alterations in ex vivo rat brain catecholamine levels in the nucleus accumbens, amygdala, and septum. In further studies, angiotensin II (Ang II) was shown to decrease potassium-stimulated [3H] acetylcholine release from slices of rat entorhinal and human temporal cortex, an effect that could be antagonized by the angiotensin receptor antagonist [1-sar,8-thr]Ang II. It is concluded that ACE inhibition can improve both basal and impaired performance in animal models of learning, and that this improvement may be in part a consequence of the removal by ACE inhibition of an inhibitory tone on central acetylcholine release, and/or an effect on central catecholaminergic function.

Acetylcholine↗

Agonist interactions with 5-HT3 receptor recognition sites in the rat entorhinal cortex labelled by structurally diverse radioligands.

1. The pharmacological properties of 5-HT3 receptor recognition sites labelled with [3H]-(S)-zacopride, [3H]-LY278,584, [3H]-granisetron and [3H]-GR67330 in membranes prepared from the rat entorhinal cortex were investigated to assess the presence of cooperativity within the 5-HT3 receptor complex. 2. In rat entorhinal cortex homogenates, [3H]-(S)-zacopride, [3H]-LY278,584, [3H]-granisetron and [3H]-GR67330 labelled homogeneous densities of recognition sites (defined by granisetron, 10 microM) with high affinity (Bmax = 75 +/- 5, 53 +/- 5, 92 +/- 6 and 79 +/- 6 fmol mg-1 protein, respectively; pKd = 9.41 +/- 0.04, 8.69 +/- 0.14, 8.81 +/- 0.06 and 10.14 +/- 0.04 for [3H]-(S)-zacopride, [3H]-LY278,584, [3H]-granisetron and [3H]-GR67330, respectively, n = 3-8). 3. Quipazine and granisetron competed for the binding of each of the radioligands in the rat entorhinal cortex preparation at low nanomolar concentrations (pIC50; quipazine 9.38-8.51, granisetron 8.62-8.03), whilst the agonists, 5-hydroxytryptamine (5-HT), phenylbiguanide (PBG) and 2-methyl-5-HT competed at sub-micromolar concentrations (pIC50; 5-HT 7.16-6.42, PBG 7.52-6.40, 2-methyl-5-HT 7.38-6.09). 4. Competition curves generated with increasing concentrations of quipazine, PBG, 5-HT and 2-methyl-5-HT displayed Hill coefficients greater than unity when the 5-HT3 receptor recognition sites in the entorhinal cortex preparation were labelled with [3H]-LY278,584, [3H]-granisetron and [3H]-GR67330. These competing compounds displayed Hill coefficients of around unity when the sites were labelled with [3H]-(S)-zacopride. Competition for the binding of [3H]-(S)-zacopride, [3H]-LY278,584, [3H]-granisetron and [3H]-GR67330 by granisetron generated Hill coefficients around unity.5. The nature of the interaction of competing compounds (quipazine, granisetron, PBG, 5-HT, 2-methyl-5-HT) for the [3H]-(S)-zacopride binding site in the rat entorhinal cortex preparation was not altered by the removal of the Krebs ions or the addition of the monoamine oxidase inhibitor, pargyline, to the HEPES/Krebs buffer.6. In conclusion, the present studies provide further evidence towards the presence of cooperativity within the 5-HT3 receptor macromolecule and indicate that either [3H]-(S)-zacopride labels a different site on the receptor complex from [3H]-LY278,584, [3H]-granisetron or [3H]-GR67330, or it binds in such a manner as to prevent the conformatory change in the receptor protein responsible for the cooperative binding of agonists (and quipazine).

Animals↗

Identification and distribution of 5-HT3 recognition sites in the rat gastrointestinal tract.

1. Tritiated derivatives of the potent and selective 5-HT3 receptor antagonists GR65630 and LY278584 were used to identify 5-HT3 recognition sites in the rat gastrointestinal tract. 2. Binding studies were carried out in homogenates of the rat oesophagus, the cardia, fundus, body and antrum of the stomach, regions of the small intestine, caecum and large intestine. The specific binding of a single concentration of GR65630 (0.5 nM) defined by granisetron (10 microM) in these areas indicated that the density of 5-HT3 recognition sites varied from 2.4 +/- 1.0 to 10.1 +/- 1.0 fmol mg-1 protein. 3. Saturable binding of [3H]-GR65630 could only be demonstrated in the terminal regions of the small intestine (Bmax in the range of 13.83 +/- 4.54-21.19 +/- 0.89 fmol mg-1 protein; mean +/- s.e. mean) and of high affinity (Kd in the range of 0.42 +/- 0.18-0.79 +/- 0.24 nM). Use of [3H]-LY278584 revealed a similar binding density (Bmax 19.54 +/- 0.26 fmol mg-1 protein) and affinity (Kd 1.04 +/- 0.07 nM) in the terminal small intestine. 4. Binding of [3H]-GR65630 and [3H]-LY278584 to the terminal region of the small intestine was inhibited by 5-HT3 receptor ligands ondansetron and S-zacopride (and 5-hydroxytryptamine), but not by 5-HT1, 5-HT2, catecholamine, gamma-aminobutyric acid and opioid receptor ligands. 5. These data demonstrate that there are regional variations in the density of 5-HT3 recognition sites within the rat gastrointestinal tract. Such data are relevant to the potential use of 5-HT3 receptor ligands to modify secretory and contraction responses in the gastrointestinal system.

Affinity Labels↗

Differential modulation of extracellular levels of 5-hydroxytryptamine in the rat frontal cortex by (R)- and (S)-zacopride.

1. The ability of various anxiolytic and potential anxiolytic agents to modify 5-hydroxytryptamine (5-HT) release in the frontal cortex of the rat was assessed by the microdialysis technique. 2. The benzodiazepine receptor agonist, diazepam (2.5 mg kg-1, i.p.), the 5-HT1A receptor agonist 8-hydroxy-2-(di-n-propylamino) tetralin (8-OH-DPAT, 0.32 mg kg-1, s.c.) and the 5-HT1A receptor partial agonist buspirone (4.0 mg kg-1, i.p.) maximally reduced extracellular levels of 5-HT in the rat frontal cortex by approximately 50-60%, 70-80% and 30-40%, respectively. 3. (R)-zacopride (1.0-100 micrograms kg-1, i.p.) dose-dependently reduced extracellular levels of 5-HT in the rat frontal cortex (approximately 80% maximal reduction) whereas the other 5-HT3 receptor antagonists ondansetron (10 micrograms kg-1, i.p.) and (S)-zacopride (10-100 micrograms kg-1, i.p.) were ineffective. 4. In contrast to (S)-zacopride (100 nM; administered via the microdialysis probe), (R)-zacopride (1.0-100 nM; administered via the microdialysis probe) induced a concentration-dependent reduction in extracellular levels of 5-HT in the rat frontal cortex (approximately 70% maximal reduction). 5. In contrast to ondansetron (100 micrograms kg-1, i.p.), (S)-zacopride (10-100 micrograms kg-1, i.p.) dose-dependently reversed the (R)-zacopride (10 micrograms kg-1, i.p.) induced reduction in extracellular levels of 5-HT in the rat frontal cortex. The highest dose of (S)-zacopride (100 micrograms kg-1, i.p.) completely prevented the (R)-zacopride response.In addition, (S)-zacopride (100 nM; administered via the microdialysis probe) attenuated the inhibitory action of (R)-zacopride (10 nM; administered via the microdialysis probe) on extracellular levels of 5-HT in the rat frontal cortex.6. In conclusion, the present study provides further evidence of the ability of diazepam, 8-OH-DPAT and buspirone to reduce the activity of the central 5-hydroxytryptaminergic system in vivo. Furthermore,the results indicate that the ability of (R)-zacopride to reduce the in vivo release of 5-HT in the rat frontal cortex does not correlate with its 5-HT3 receptor antagonism. However, the differential affinity of (R)- and (S)-zacopride for a (S)-zacopride-insensitive (R)-zacopride site in rat cerebral cortex mirrors the relative activity of the two zacopride stereoisomers to modify the in vivo release of 5-HT in the frontal cortex of the rat and their ability to release suppressed behaviour in animal models of anxiety.

8-Hydroxy-2-(di-n-propylamino)tetralin↗

Anxiolytic potential of 5-HT3 receptor antagonists.

The 5-HT3 receptor antagonists such as ondansetron have been shown to have anxiolytic-like activity in a wide range of preclinical tests: in the mouse black: white test, the rat social interaction test, the rat elevated X-maze and the marmoset human threat test. Ondansetron, like other 5-HT3 receptor antagonists appears to have important advantages over existing anxiolytic therapies. Thus, the 5-HT3 receptor antagonists are not sedative, they do not have addictive liabilities, there are no problems of withdrawing from chronic treatment and they can be used following benzodiazepine withdrawal. Such compounds even inhibit the behavioural syndrome associated with withdrawal from drugs of abuse, nicotine, alcohol, cocaine, opiates. The preclinical data, therefore, indicates the 5-HT3 receptor antagonists as novel anxiolytics of the future, and there is new clinical work in support of this suggestion.

Animals↗