Baetid abundances are a rapid indicator of thermal stress and riparian zone intactness.

Riparian zone vegetation plays an integral role in freshwater ecology, notably by buffering water temperatures, and in providing habitat for the adult stages of many aquatic species. We measured the contribution that riparian vegetation makes to temperature buffering, and how this affects the freshwater fauna, specifically using changes in abundances of baetid may flies for the Luvuvhu River catchment in South Africa. Water temperatures were compared for shaded versus un-shaded sites, and thermal stress between seasons was estimated using a cumulative probability model for the most widespread mayfly species, Dabulamanzia media. It is concluded that thermal stress due to losses in riparian shading could be detected using mayfly abundances in a regular monitoring programme.

Wide variation and systematic bias in expert clinicians' perceptions of prognosis following brain injury.

BACKGROUND: The heterogeneous nature of traumatic brain injury (TBI) makes outcome prediction difficult. Although a considerable evidence base exists in the form of well-validated predictive models, these models are not widely used. We hypothesised that this prognostic gap, between the availability and use of prognostic data, leads to inaccurate perceptions of patient outcome. We investigated whether outcome predictions in TBI made by expert clinicians were consistent and accurate when compared to a well-validated prognostic model (IMPACT). METHODS: Neurosurgeons and neurointensivists were asked to predict probability of death at 6 months for 12 case vignettes describing patients with isolated TBI. Predictions were compared to IMPACT prognosis for each vignette. To interrogate potential sources of bias in clinical predictions, respondents were given one of two sets of vignettes (A or B) identical apart from one critical factor known to make a large difference to outcome. RESULTS: 27 of 33 questionnaires were returned. Clinicians were consistently more pessimistic about outcomes than the IMPACT model, predicting a significantly greater probability of death (mean difference + 16.3%, 95% CI 13.3-19.4, p < 0.001). There was wide variation between clinicians predicting outcomes for any given vignette (mean range 68.3%), and within the predictions made by each individual: 30% of clinicians were both the most pessimistic respondent, and the most optimistic, for at least one vignette. Clinicians modified their predictions appropriately for most of the factors altered between corresponding vignettes. However when the reported blood glucose was changed, clinicians' predictions deviated widely from IMPACT predictions, indicating that clinicians systematically overlooked the prognostic relevance of this information. CONCLUSION: Clinical experts' predictions of outcome in TBI are widely variable and systematically pessimistic compared to IMPACT. Clinicians overlook important factors in formulating these predictions. Use of well-validated outcome models may add value and consistency to prognostication.

Evaluation of larvicides in developing management guidelines for long-term control of pest blackflies (Diptera: Simuliidae) along the Orange River, South Africa.

In 2000 and 2001 Orange River levels were higher than normal: associated serious outbreaks of blackfly had a substantial detrimental impact on the local economy. The poor control was attributed to the suspected development of larval resistance to temephos. A long-term solution to blackfly control, through the identification of a suitable replacement to temephos for use during high flow conditions, was proposed. This study, however, failed to identify or register a suitable larvicide for use during high flow conditions. Although permethrin was highly effective against blackfly larvae, it was rejected because of its detrimental impacts on non-target fauna. Various formulations of locally produced dry Bacillus thuringiensis var. israelensis (B.t.i.) were tested, but these were ineffective against blackflies. The study also confirmed that resistance to temephos has developed among Simulium chutteri in the middle and lower Orange River. The feasibility of "reversing" the resistance to temephos through the use of the synergist piperonyl butoxide (PBO) was investigated, but the results were not favourable. Furthermore, PBO was highly toxic to blackflies and non-target organisms, and was not recommended for further testing. This means that B.t.i. currently remains the only symptomatic measure of treatment currently applied. Although resistance to B.t.i. has not been reported for blackflies elsewhere in South Africa, there is a need to remain vigilant and to implement an operational strategy that minimizes the risks of resistance developing.

Combined growth-inhibitory responses and ultrastructural alterations produced by 1,3-bis(2-chloroethyl)-1-nitrosourea and dexamethasone in rat glioma cell cultures.

The effect of 0.0001 to 10 muM 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU) and 1 muM dexamethasone on cell proliferation was studied by measuring cell densities in control and drug-treated rat glioma (strain C6) monolayer cultures. When C6 cultures were exposed to 0.01 to 10 muM BCNU, the growth rates decreased for 2 days as control cell populations continued to proliferate at log phase rates. These growth-inhibitory responses were dose dependent and ranged from 20 to 80%, relative to control growth. Subsequently, the growth rates increased and the inhibitory responses ranged from 0 to 12% 4 days later. Cell densities in C6 cultures exposed to 1 muM dexamethasone for 1 day did not differ significantly from controls. Then cell proliferation ceased and the inhibitory response remained at 50% relative to controls in stationary phase. When 0.03 muM BCNU and 1 muM dexamethasone were supplied simultaneously to C6 cultures, a 35% inhibitory response occurred after 1 day. This response did not differ significantly from that observed with 0.03 muM BCNU alone. After 4 days, the inhibitory response did not decrease in cultures containing both drugs, but did decrease to 13% in the 0.03 muM BCNU-treated cultures. In 1 muM BCNU-treated cultures, the response was 66% after 1 day, which decreased to 21% 5 days later. When 1 muM BCNU was supplied to C6 cultures that were pretreated for 1 day with 1 muM dexamethasone, the response was 91% the following day, and this decreased to only 54% 5 days later. Dose-response curves showed that the inhibitory responses after 1 day in these pretreated cultures exposed to 0.001 to 10 muM BCNU increased up to 22% relative to the responses produced by either drug alone. After 5 days, the responses in the pretreated cultures exposed to 0.001 to 1 muM BCNU was 50%, which was similar to the response produced by 1 muM dexamethasone alone. Ultrastructural studies revealed that control and 1 muM BCNU-treated C6 cells contained 18 mitochondria, but the treated cells were 10% smaller after 1 day. Cells exposed to 1 muM dexamethasone for 1 day conount of granular endoplasmic reticulum increased greater than 80% in cells treated with BCNU for 1 day or dexamethasone for 2 days. C6 cells pretreated with dexamethasone and exposed to BCNU for an additional day (a) contained 23 mitochondria, (b) did not decrease in size, and (c) exhibited a greater than 250% increase in the amount of granular endoplasmic reticulum. These results demonstrate that combined growth-inhibitory responses and ultrastructural alterations occur when C6 cells are treated sequentially with 1 muM dexamethasone and BCNU.

Radioreceptor binding profile of the atypical antipsychotic olanzapine.

The affinities of olanzapine, clozapine, haloperidol, and four potential antipsychotics were compared on binding to the neuronal receptors of a number of neurotransmitters. In both rat tissues and cell lines transfected with human receptors olanzapine had high affinity for dopamine D1, D2, D4, serotonin (5HT)2A, 5HT2C, 5HT3, alpha 1-adrenergic, histamine H1, and five muscarinic receptor subtypes. Olanzapine had lower affinity for alpha 2-adrenergic receptors and relatively low affinity for 5HT1 subtypes, GABAA, beta-adrenergic receptors, and benzodiazepine binding sites. The receptor binding affinities for olanzapine was quite similar in tissues from rat and human brain. The binding profile of olanzapine was comparable to the atypical antipsychotic clozapine, while the binding profiles for haloperidol, resperidone, remoxipride, Org 5222, and seroquel were substantially different from that of clozapine. The receptor binding profile of olanzapine is consistent with the antidopaminergic, antiserotonergic, and antimuscarinic activity observed in animal models and predicts atypical antipsychotic activity in man.

Effect of L-type calcium channel modulators on stimulant-induced hyperactivity.

The present study investigated the effect of L-type calcium channel modulators on stimulant-induced locomotor activity. The L-channel activator, (+/-)BayK8644, produced a marked, long-lasting enhancement of cocaine-induced activity, while having no effect on amphetamine hyperactivity. Nicardipine reduced cocaine hyperactivity but had no effect on the amphetamine response.

Light and electron microscopic observations of epithelial shedding in stored canine small intestine.

Simple cold storage of canine small intestine is accompanied by ischemic damage to the intestinal mucosa. Progression of damage observed during cold storage is unique and has not been observed with other organs. The mucosal damage begins within 15 min after the onset of the storage, with progressive involvement of the gut as the storage period lengthens. Cytoplasmic blebs develop from the base of the epithelial cells and detach the epithelium from the basal lamina. While the process begins uniformly along the length of the villus, separation of the epithelium occurs first at the villus tip. The epithelium, which is shed into the intestinal lumen, is otherwise undamaged. Blebbing occurs in enteroendocrine and goblet cells and is not restricted to enterocytes. Early blebs occur in proximity to mucosal mast cells and subepithelial nerves. Tissue damage in cold is possibly related to enzymes that are still active at storage temperatures.

Behavioral pharmacology of olanzapine: a novel antipsychotic drug.

BACKGROUND: In this paper, we review the behavioral pharmacology of olanzapine and compare it to its in vitro profile and to clozapine and a number of other antipsychotic agents, and we estimate the likelihood that olanzapine will be an effective and safe antipsychotic with fewer side effects. METHOD: Since there is no model of schizophrenia, per se, a battery of behavioral assays was used. RESULTS: Behavioral assays confirmed the in vitro results that olanzapine interacts with dopamine, serotonin, and muscarinic receptor subtypes. Moreover, olanzapine appears to have a clozapine-like atypical profile based on (1) mesolimbic selectivity, (2) blocking 5-HT receptors at a lower dose than dopamine receptors, and (3) inhibiting the conditioned avoidance response (indicative of antipsychotic efficacy) at doses that are lower than those required to induce catalepsy (indicative of extrapyramidal side effects). No only is this profile similar to that of clozapine, but olanzapine has other similarities: olanzapine substitutes for clozapine in a drug discrimination assay; like clozapine and unlike "typical" antipsychotics, olanzapine increases responding in a conflict procedure; and olanzapine, like clozapine, reverses changes induced by antagonists of the NMDA receptor. CONCLUSION: On the basis of these findings, we predict that olanzapine will be an efficacious antipsychotic, active against both positive and negative symptoms, while producing fewer extrapyramidal symptoms than existing treatments.

In vitro and in vivo biochemistry of olanzapine: a novel, atypical antipsychotic drug.

BACKGROUND: Classical (typical) antipsychotic drugs are in wide use clinically, but some patients do not respond at all to treatment, while in others, negative symptoms and cognitive deficits fail to respond. Also, these drugs often cause serious motor disturbances. Clozapine, an atypical antipsychotic, appears to correct many of these deficiencies, but has a significant incidence of potentially fatal agranulocytosis. Accordingly, we attempted to develop a prototype of a new generation of antipsychotics that is both more efficacious and safe. Our strategy was to create a compound that is not only active in behavioral tests that predict antipsychotic action but also shares the rich, multifaceted receptor pharmacology of clozapine without its side effects. To this end, Eli Lilly and Co. developed olanzapine. In this article we characterize the in vitro and in vivo receptor pharmacology of olanzapine. METHOD: We evaluated olanzapine interactions with neuronal receptors using standard assays of radioreceptor binding in vitro and well-established in vivo (functional) assays. RESULTS: Binding studies showed that olanzapine interacts with key receptors of interest in schizophrenia, having a nanomolar affinity for dopaminergic, serotonergic, alpha 1-adrenergic, and muscarinic receptors. In vivo olanzapine is a potent antagonist at DA receptors (DOPAC levels; pergolide-stimulated increases in plasma corticosterone) and 5-HT receptors (quipazine-stimulated increases in corticosterone), but is weaker at alpha-adrenergic and muscarinic receptors. Olanzapine has little or no effect at other receptors, enzymes, or key proteins in neuronal function. Olanzapine has a receptor profile that is similar to that of clozapine: it is relatively nonselective at dopamine receptor subtypes and it shows selectivity for mesolimbic and mesocortical over striatal dopamine tracts (electrophysiology; Fos). CONCLUSION: The binding and functional profile of olanzapine (1) is similar to that of clozapine, (2) indicates that olanzapine is an atypical antipsychotic drug, and (3) is consistent with clinical efficacy. If olanzapine also proves to be safe, then it will have high potential to become a more ideal antipsychotic drug.

A solid phase enzyme immunoassay (ELISA) for the detection and quantitation of anticardiolipin antibody.

A solid-phase enzyme-linked immunoabsorbent assay (ELISA) is described for the detection and quantitation of anticardiolipin antibodies (ACAs) IgG and IgM in sera. In these assays, non-specific binding was controlled by using antigen-negative wells for all serum dilutions tested. Quadruplicate 100-microliters serum samples diluted 1:20 for ACA-IgG and 1:40 for ACA-IgM were incubated for two hours, after which alkaline phosphatase-conjugated antihuman IgG or IgM was added. A standard serum was used on each plate to provide reproducibility of the assay. Upper limits of normal for ACA-IgG and IgM were established by testing 161 sera from normal persons. Sixty-one selected patients with SLE were tested; and, from these results, categories of positivity were defined from negative to 4+. All screen-positive sera (greater than or equal to 1+) were assayed in a quantitative ELISA assay for ACAs, using multiple dilutions of the unknowns. These data were fit on a standard curve generated with dilutions of a reference serum on each plate using a computerized data reduction system based on the 2 Plus 2 model. The standard curves were compared with the international standards for IgG and IgM anticardiolipin. The ability to quantitate ACA concentrations allows better definition of positive sera, as well as the opportunity to accurately evaluate and follow this antibody in a variety of patient groups.

Production of climbing behaviour in mice requires both D1 and D2 receptor activation.

The ability of SKF38393 (a D1 agonist), quinpirole (a D2 agonist), and apomorphine (a mixed D1/D2 agonist) to induce stereotyped climbing behaviour in mice was investigated. Apomorphine produced a dose-related increase in stereotyped cage climbing which lasted for up to 60 min. SKF38393 and quinpirole failed to produce climbing when administered alone. When given in combination intense apomorphine-like cage climbing was observed which lasted for up to 2 h. Apomorphine or the combination of SKF38393 and quinpirole also produced biting of the cage. The climbing behaviour produced by either apomorphine or SKF38393/quinpirole combinations was antagonised by either the D1 antagonist, SCH23390 or the D2 antagonist clebopride. These results demonstrate that both D1 and D2 receptor activation is necessary to produce apomorphine-like cage climbing in mice.

Acute Cerebral Artery Constriction in the Spontaneously Hypertensive Rat following Blood and Plasma Administration into the Subarachnoid Space.

The purpose of the present study was to demonstrate, using a vascular casting technique, acute vasoconstrictive changes in the cerebral vasculature 1 h following whole-blood or plasma infusion into the subarachnoid space of conscious spontaneously hypertensive rats. Vascular casts from animals infused (over 20 min) with 0.45 ml of heparinized autologous arterial blood or plasma exhibited incomplete filling, while casts from saline-infused controls exhibited virtually no filling defects. Significant elevations in intracranial pressure were noted in blood, but not in plasma- or saline-infused rats. Two characteristic forms of constriction occurred, depending upon the vessel lumen diameter. Vessels with lumen diameters >100 &mgr;m were flattened longitudinally with deep endothelial nuclear imprints, while smaller vessels had focal circular constrictions resembling beads. Arterial cast filling terminated in vessels with lumen diameters from 70 to 120 &mgr;m with focal signs of constriction at or near the point of cast termination. The results indicate that the presence of both blood and plasma in the subarachnoid space produces acute small-artery constriction. This phenomenon is due to a noncellular blood component and does not correlate with increases in intracranial pressure. Copyright 1996 S. Karger AG, Basel

The role of multiple dopamine receptors in apomorphine and N-n-propylnorapomorphine-induced climbing and hypothermia.

Apomorphine and N-n-propylnorapomorphine (NPA) were compared for their ability to induce stereotyped cage climbing and hypothermia in mice. Climbing behavior was produced by similar doses of apomorphine and NPA (0.625-2.5 mg/kg s.c.), whereas NPA was 43 times more potent than apomorphine in inducing a hypothermic response. SKF38393 caused a shift to the left in the dose-response curve for NPA-induced climbing, the ED50 changing from 0.98 to 0.014 mg/kg. SKF38393 had no effect on apomorphine-induced climbing behaviour. The climbing response produced by apomorphine was antagonised by both D-1 and D-2 antagonists. Climbing behaviour induced by NPA (2.5 mg/kg) could be antagonised by SCH23390 but not by clebopride, however climbing behaviour induced by a low dose of NPA (0.06 mg/kg) plus SKF38393 could be blocked by both D-1 and D-2 receptor antagonists. The hypothermic responses produced by either apomorphine or NPA could only be reversed by the selective D-2 antagonist, clebopride. These results demonstrate that dopamine agonist-induced stereotyped cage climbing requires both D-1 and D-2 receptor stimulation, whereas the hypothermic response is D-2-mediated. The results also show that it is possible to assess the relative activity of a dopamine agonist at D-1 or D-2 receptors in vivo by comparing the ability of the compound to induce hypothermia and climbing behaviour.

NMDA receptor antagonists inhibit catalepsy induced by either dopamine D1 or D2 receptor antagonists.

In the present study, we investigated the ability of NMDA receptor antagonists to inhibit catalepsy induced by haloperidol, or SCH23390 and clebopride, selective dopamine D1 and D2 receptor antagonists respectively. Catalepsy was measured by recording the time the animal remained with its forepaws placed over a rod 6 cm above the bench. Pretreatment with either the non-competitive NMDA receptor antagonist, MK-801 (0.25-0.5 mg/kg i.p.) or the competitive antagonist, LY274614 (10-20 mg/kg i.p.) reduced the cataleptic response produced by haloperidol (10 mg/kg), SCH23390 (2.5-10 mg/kp i.p.) or clebopride (5-20 mg/kg i.p.). This demonstrates that NMDA receptor antagonists will reduce both dopamine D1 and D2 receptor antagonist-induced catalepsy. Muscle relaxant doses of chlordiazepoxide (10 mg/kg i.p.) failed to reduce the catalepsy induced by haloperidol, suggesting that the anticataleptic effect of the NMDA receptor antagonists was not due to a non-specific action. These results support the hypothesis that NMDA receptor antagonists may have beneficial effects in disorders involving reduced dopaminergic function, such as Parkinson's disease.

Effects of olanzapine and other antipsychotic agents on responding maintained by a conflict schedule.

The effects of the "atypical" antipsychotic olanzapine and several other antipsychotics were examined using a conflict schedule. Rats were trained to respond for food on a three-component schedule, comprising variable-interval 30s (food, VI30) and fixed-ratio 10s (food + shock, FR10) components separated by time-out (TO). Olanzapine (0.3125-1.25mg/kg), clozapine (1.25-5mg/kg) and chlordiazepoxide (2.5-5mg/kg) decreased or had no effect on VI30 responding, whereas responding in the FR10 component increased. Chlordiazepoxide (5mg/kg) also increased TO responding. The antipsychotic agents haloperidol (0.125 and 0.25mg/kg), trifluoperazine (0.0625-0.25mg/kg), remoxipride (1.25-5mg/kg) and risperidone (0.0625-0.5mg/kg) decreased V130 responding and either had no effect, or decreased TO and FR10 rates. The anticholinergic agent scopolamine (0.03125-0.25mg/kg) decreased VI30 responding. The 5-HT(2) antagonist ritanserin (2.5 and 5mg/kg) and the anticholinergic agent trihexyphenidyl (2.5 and 5mg/kg) had no effect on responding. Flumezanil (10mg/kg) reduced the anticonflict effect of chlordiazepoxide but not olanzapine. These results further emphasize the unusual profile of olanzapine.

5-HT1A-mediated lower lip retraction: effects of 5-HT1A agonists and antagonists.

This study investigated the production of lower lip retraction (LLR) in the rat by the 5-hydroxytryptamine1A (5-HT1A) agonist 8-hydroxy-2-(di-n-propylamino)-tetralin (8-OH-DPAT) and the effect of the putative 5-HT1A antagonists pindolol and (1-(2-methoxy-phenyl)-4-[4-(2-phthalimido)-butyl]-piperazine (NAN190). 8-OH-DPAT (0.125-1.0 mg/kg, IP) caused a dose-related increase in LLR. Pindolol (10-40 mg/kg, IP) and NAN190 (2.5-10 mg/kg, IP) produced a dose-related block of 8-OH-DPAT-induced LLR. Pindolol (10-40 mg/kg, IP) when administered alone was also found to cause LLR, suggesting that pindolol behaves as a partial agonist in this model. This was not the case with NAN190 (2.5-10 mg/kg, IP), which failed to produce LLR; however, NAN190 (2.5-10 mg/kg, IP) produced a dose-related block of the pindolol-induced LLR. These results clearly demonstrate that the LLR model can be used to detect 5-HT1A agonists, partial agonists, and antagonists.

A method for evaluation of brain tumor growth using implantable diffusion chambers.

Major drawbacks associated with in vitro assays for sensitivity of brain tumors to specific chemotherapeutic drugs include uncertainty of end-point validity, the need for large tissue samples, and cost. Furthermore, these assays do not address the question of conversion of the drug to active moeities by metabolic pathways in the host or alteration of drug activity by binding to plasma protein. We propose to develop a technique for growth and quantitation of tumor cells in small-pore diffusion chambers that contain the tumor cells and protect them from the immune system of the immunologically unrelated host. These chambers, fabricated from acrylic rings and membranes of 0.22 microns pore size, are sterilized, filled with a precisely quantitated inoculum of tumor cells, and implanted in the peritoneal cavity of rats. Replication of the cells is determined by enzymatic digestion of the supporting matrix of the cells within the chamber and counting the single cell suspension with a hemocytometer or automated cell counter. Precise comparison can thus be made between different drugs regarding their effect on cell growth in the host. This assay can be performed with the basic equipment and personnel available in most cell culture laboratories and requires a small number of tumor cells. Mass production of the diffusion chambers may make the assay less costly and faster than assays that do not involve exposure of tumor to drug in a living host. In addition, the assay should permit screening of new chemotherapeutic agents against human tumors under physiologic conditions.

Behavioural pharmacology of the new generation of antipsychotic agents.

In conclusion, the newer agents all have behavioural profiles which can be clearly differentiated from those of the older, classical agents. Behavioural data indicate that to a greater or lesser extent, all the newer antipsychotics will produce fewer acute EPS than the older agents. However, the new 'atypical' agents all have distinct profiles. Olanzapine has a profile similar to that of clozapine, albeit somewhat more potent. Olanzapine, like clozapine, displays a wide margin between the doses predictive of efficacy and those which induce EPS. The compound also substitutes for clozapine in drug discrimination assays and increases punished responding in a conflict paradigm. Quetiapine also has a clozapine-like profile, although it lacks the cholinergic receptor affinity and is relatively weak in most behavioural assays. Quetiapine, like olanzapine, also reverses PCP-induced deficits, and substitutes for clozapine in drug discrimination assays. However, no data are currently available regarding quetiapine's action in anxiolytic tests. Risperidone, sertindole and ziprasidone have profiles of activity different from those of older agents, predominantly due to their 5-HT2a affinity. All these agents possess some properties similar to those of clozapine, but there are some differences: for example, risperidone and sertindole fail to substitute for clozapine in drug discrimination assays and are inactive in classical conflict models of anxiety. It is more difficult to make an accurate assessment of the behavioural profile of ziprasidone, due to a lack of published data. Given the behavioural differences exhibited by animals receiving the new antipsychotic agents, one would predict that these drugs will have distinct clinical profiles. All the agents display activity indicative of agents with a reduced propensity to induce EPS. However, significant differences may be observed in their efficacy against negative and cognitive symptoms. It will be important to assess the clinical profiles of these agents carefully if the predictive value of the pre-clinical 'models' is to be improved.

Olanzapine: preclinical pharmacology and recent findings.

Olanzapine possesses a broad pharmacological profile, interacting with a range of different neurotransmitter receptors. Although its affinity for muscarinic receptors is relatively greater than for dopamine receptors, on schedule-controlled behaviour olanzapine displays a profile resembling a dopamine antagonist. Likewise, in a test of cognitive function, olanzapine does not produce anticholinergic-like deficits. In drug discrimination assays, olanzapine substitutes for clozapine in clozapine-trained animals and clozapine generalises to olanzapine in olanzapine-trained animals. Olanzapine also reverses the behavioural deficits produced by inhibiting N-methyl-D-aspartate receptor glutamatergic transmission. This profile suggests that olanzapine will be effective against both positive and negative symptoms of schizophrenia while producing minimal extrapyramidal side-effects.

Olanzapine: a basic science update.

Olanzapine, an atypical antipsychotic, has a broad receptor binding profile, which may account for its pharmacological effects in schizophrenia. In vitro receptor binding studies showed a high affinity for dopamine D2, D3, and D4 receptors; all 5-HT2 receptor subtypes and the 5-HT6 receptor; muscarinic receptors, especially the M1 subtype: and alpha 1-adrenergic receptors. In vivo studies showed that olanzapine had potent activity at D2 and 5-HT2A receptors, but much less activity at D1 and muscarinic receptors, and that it inhibited dopaminergic neurons in the A10 but not the A9 tract, suggesting that this agent will not cause extrapyramidal side-effects (EPS). Microdialysis studies showed that olanzapine increased the extracellular levels of norepinephrine and dopamine, but not 5-HT, in the prefrontal cortex, and increased extracellular dopamine levels in the neostriatum and nucleus accumbens, areas of the brain associated with schizophrenia. Studies of gene expression showed that olanzapine 10 mg/kg also increased Fos expression in the prefrontal cortex, the dorsolateral striatum, and the nucleus accumbens. These findings are consistent with the effectiveness of olanzapine on both negative and positive symptoms and suggest that, with careful dosing, olanzapine should not cause EPS.