The experimental induction of leukoencephalomyelopathy in cats

Leukoencephalomyelopathy of undetermined etiology has been described in specific pathogen-free cats. A study was established to assess if the long-term feeding of a gamma-irradiated diet could induce this disease. Cats fed exclusively on diet irradiated at 25.7-38.1 kGy ("typical" dose) and 38.1-53.6 kGy (high-end dose), respectively, developed typical lesions with attendant, progressively severe ataxia between study days 140 and 174. The onset of ataxia at day 140 and the number of animals affected at this time were similar in animals fed each ration. A maximum ataxia "score" was first reached by an animal on the high-end dose diet on day 167 and by 2 cats fed the "typical-end" dose diet 21 days later. Ataxic cats and 1 animal euthanized on day 93 prior to the onset of ataxia exhibited varying degrees of Wallerian degeneration in the spinal cord and brain, similar to the spontaneous disease. The elevated total antioxidant status of spinal cord segments and hepatic superoxide dismutase concentration of cats fed typical and high-end treated diets suggested free-radical involvement in the pathogenesis. The significantly elevated peroxide concentrations of the irradiated diets (1,040% and 6,440% of untreated values) may have resulted in increased oxidative insult, a factor possibly exacerbated by the treated diets' reduced vitamin A content. This study has reproduced leukoencephalomyelopathy in cats similar to spontaneous outbreaks by feeding a gamma-irradiated dry diet with elevated peroxide and reduced vitamin A concentrations.

Drugs in the aetiology of agranulocytosis and aplastic anaemia

Agranulocytosis and aplastic anaemia are rare but serious conditions known to be caused by numerous drugs. Most of what is known or suspected about the aetiology is based on case reports, with only a few formal epidemiological studies that provide quantitative estimates of risk. Updated results have been obtained from a combined analysis of data from 3 case-control studies that used similar methods: the International Agranulocytosis and Aplastic Anemia Study (IAAAS), conducted in Israel and Europe; a study conducted in the northeast US; and a study conducted in Thailand. Totals of 362 cases of agranulocytosis, 454 cases of aplastic anaemia and 6458 controls were included in the analyses. The IAAAS and Thai study were population-based, providing estimates of the incidence of the 2 dyscrasias. The overall annual incidence of agranulocytosis in the ambulatory population was 3.4/10(6) in the IAAAS and 0.8/10(6) in Thailand; by contrast the incidence of aplastic anaemia was 2.0/10(6) in the IAAAS and 4.1/10(6) in Thailand. A total of 21 compounds were significantly associated with an increased risk of agranulocytosis in the IAAAS and US studies. Excess risks ranged from 0.06 to 13 cases/10(6) users/wk; the most strongly associated drugs were procainamide, anti-thyroid drugs and sulphasalazine. An association with drugs that had previously been suspected was also seen in Thailand. The overall aetiologic fractions of agranulocytosis due to drug use were 62% in the IAAAS, 72% in the US and 70% in Thailand. Eleven drugs were significantly associated with an increased risk of aplastic anaemia, with excess risks ranging from 1.4 to 60 cases/10(6) users in a 5-month period. The most strongly associated drugs were penicillamine, gold and carbamazepine. Aetiologic fractions were 27% in the IAAAS, 17% in the US and 2% in Thailand, which paralleled the prevalence of use of associated drugs in the 3 populations. The present results confirm that agranulocytosis is largely a drug-induced disease, with similar proportions accounted for in 3 disparate geographic regions. By contrast, although many of the expected associations were observed for aplastic anaemia, most of the aetiology is not explained by drugs. For all associated drugs, the excess risks are sufficiently low that blood dyscrasias should not figure prominently in the balancing of risks and benefits.

An epidemiological study of aplastic anaemia: relationship of drug exposures to clinical features and outcome

Two hypotheses were examined in the combined data from 3 case-control studies of aplastic anaemia, conducted in Thailand, Europe/Israel and the US: 1. Cases exposed to drugs associated with a significantly increased risk of aplastic anaemia are more likely to present with thrombocytopenia (e.g. petechiae, easy bruising); and 2. cases exposed to these drugs are more likely to recover quickly than non-exposed cases. After excluding all cases who lacked information on timing of symptoms and those whose symptoms began > or = 180 d before hospital admission, 392 cases remained for analysis. A total of 51 (13%) had been exposed to one of the significantly associated drugs; the remaining 341 (87%) had not. Among the former, 31% reported thrombocytopenia either before or at the same time as non-bleeding symptoms (e.g. pallor, fatigue); the corresponding proportion among the non-exposed was 53%. Data on time to recovery (return of the 3 blood cell lines to normal levels) were not available for the Thai cases; among the others, the median time to recovery for the non-fatal cases was 7 and 6 months in the 29 exposed and the 83 non-exposed cases, respectively. The data do not support either hypothesis: the two groups of aplastic anaemia cases appeared to be similar in both the presenting symptoms and the recovery time.

Effect of traumatic subarachnoid haemorrhage on neuropsychological profiles and vocational outcome following moderate or severe traumatic brain injury

OBJECTIVE

Traumatic subarachnoid haemorrhage (tSAH) frequently occurs in moderate or severe traumatic brain injury (TBI) and is related to worse outcome at time of discharge from the acute hospitalization. The current study compared neuropsychological impairment and vocational outcome at 1-year post-injury in patients with and without tSAH.

DESIGN

Acute injury, neuroradiological, neuropsychological and vocational data were collected for 100 patients admitted for neurorehabilitation following TBI.

RESULTS

Patients with tSAH had significantly worse vocational outcome than patients without tSAH. On neuropsychological measures, patients with tSAH generally performed worse than patients without tSAH across most neurocognitive domains. However, differences in neuropsychological test performance between patients with and without tSAH reached statistical significance on measures of visuospatial processing, verbal reasoning and mood only.

CONCLUSION

The presence of tSAH appears to be associated with worse vocational outcome in survivors of moderate or severe TBI. As such, the presence of tSAH appears to have predictive value with respect to outcome following TBI.

Serotonergic mediation of the antidepressant-like effects of nitric oxide synthase inhibitors

Recent studies indicate that nitric oxide (NO) synthase inhibitors have antidepressant-like potential in various animal models. In the present study the behavioural activity of the NO synthase inhibitors, N(G)-nitro-L-arginine (L-NA) and 7-nitroindazole (7-NI), were assessed in a modified rat forced swimming test (FST). Both L-NA and 7-NI, dose dependently reduced immobility and increased swimming behaviour in the rat FST. This behavioural profile parallels the one previously shown with selective serotonin re-uptake inhibitors and serotonergic agonists. Thus, we examined the role of serotonin mediating the behavioural effects of L-NA and 7-NI in the rat FST. Depletion of endogenous serotonin using para-chlorophenylalanine (pCPA; 3 x 150 mg/kg, i.p.) completely blocked L-NA (20 mg/kg, i.p.) and 7-NI (20 mg/kg, i.p.)-induced reductions in immobility and increases in swimming behaviour during the FST. In conclusion these observations suggest that NO synthase inhibitors elicit their antidepressant-like activity in the modified swimming test through a serotonin dependent mechanism.

Acuity, ophthalmoscopy, and visually evoked potentials in the prediction of visual outcome in infants with bilateral optic nerve hypoplasia

PURPOSE

To determine whether Teller Acuity Cards, transient visually evoked potentials (VEPs), and optic disc size estimated from ophthalmoscopy were predictive of acuity outcome in infants and young children with bilateral optic nerve hypoplasia (ONH).

METHODS

Twenty-eight infants (mean age, 7 months) with bilateral ONH underwent clinical assessment, including ophthalmoscopy. All but a few of these patients underwent neuroimaging studies, analysis of transient VEPs to multiple stimuli, and repeated acuity assessment. Acuity outcome was assessed, on average, 28 months later.

RESULTS

Acuity outcome was significantly correlated with the estimated optic disc diameter, initial acuity, and VEP signal-to-noise ratios (r = 0.80, 0.71, 0.69, respectively; all P <.001). Multiple regression analysis showed that the initial acuity and estimated optic disc diameter accounted for 73% of the variation in acuity outcome. VEPs to white-black gratings segregated infants by 6 months of age, whose acuity outcome was better or worse than 5.6 cycles/degree (20/100).

CONCLUSIONS

Acuity outcome was predicted in infants with bilateral ONH with a linear equation using initial acuity and estimated optic disc diameter. Additionally, analysis of VEPs may segregate infants with a good visual outcome from those with a poor visual outcome. Longer follow-up will be necessary to determine final Snellen acuity.

Effects of acute and chronic administration of selective monoamine re-uptake inhibitors in the rat forced swim test

The rat forced swim test (FST) is a model that is used extensively as a screening test for antidepressant activity. It has previously been reported that thorough analysis of behaviour in this model reveals two distinct types of active response - climbing and swimming - and that these are separately evoked by re-uptake inhibitors selective for noradrenaline (NA) and serotonin (5-HT), respectively. In the present study, utilising re-uptake inhibitors selective for NA, talsupram, and 5-HT, 5-chloro-1-(3-dimethylaminopropyl)-1-(4-fluorophenyl)- phthalan (Lu 10-134-C), we examined if this scoring technique could detect the antidepressant potential of a selective serotonin re-uptake inhibitor (SSRI), and whether re-uptake inhibitors selective for distinct monoamine systems induce exclusive behavioural responses. We also analysed if chronic antidepressant administration for three weeks was more effective than acute treatment. We found Lu 10-134-C (40 mg/kg; PO) to be behaviourally active in this paradigm. Although treatment with talsupram (40 mg/kg; PO) resulted solely in climbing behaviour, Lu 10-134-C induced both climbing and swimming behaviour. However, chronic pre-treatment with either re-uptake inhibitor (20 mg/kg; twice daily; PO) failed to augment the response observed with acute treatment. Similarly, chronic administration of either compound was without effect on the basal, or stress-induced, serum corticosterone concentrations or anterior pituitary (AP) preproopiomelanocorticotropin (POMC) mRNA expression. These results suggest that selective monoamine re-uptake inhibition produces distinct, but not necessarily exclusive, behavioural responses in the forced swim test.

The effect of lofepramine and other related agents on the motility of Tetrahymena pyriformis

Tricyclic antidepressants (TCAs) were introduced almost 50 years ago. Whilst there is no doubt that TCAs are effective in treating depression, they are also more cardiotoxic when taken in overdose than other antidepressant groups. Lofepramine is a more recently introduced modified TCA, which in animals and man has low toxicity when compared to older TCAs. Paradoxically, lofepramine is extensively metabolised to desipramine, which has considerable toxicity, both experimentally and in overdose. The toxicity of such compounds is attributed, in part, to a membrane stabilising effect (MSA) on cell membranes. This MSA causes gross effects to the cell structure and in turn, normal cell activity. The aim of this study was to compare the MSA of lofepramine with that of desipramine and amitriptyline in order to see if this might help to explain the low toxicity of lofepramine. The local anaesthetic agent lignocaine was also studied for comparison. Each compound was enclosed in a beta-cyclodextrin to increase its solubility in aqueous medium. The extent of MSA was determined as a measure of the effect on the swimming speed of the protozoan Tetrahymena pyriformis using a video image analysis system. The IC50s for the various drugs were then correlated with their respective octanol-water partition coefficient values (Pow). Amitriptyline had an IC50 of 1.26+/-0.29 mM, desipramine 75.99+/-14.40 mM, while lofepramine had an IC50 of 357.40+/-25.00 mM. Lignocaine had an IC50 of 85.73+/-18.30 mM. There was also a significant correlation between the IC50 values and the Pow values.

The minimally conscious state: definition and diagnostic criteria

OBJECTIVE

To establish consensus recommendations among health care specialties for defining and establishing diagnostic criteria for the minimally conscious state (MCS).

BACKGROUND

There is a subgroup of patients with severe alteration in consciousness who do not meet diagnostic criteria for coma or the vegetative state (VS). These patients demonstrate inconsistent but discernible evidence of consciousness. It is important to distinguish patients in MCS from those in coma and VS because preliminary findings suggest that there are meaningful differences in outcome.

METHODS

An evidence-based literature review of disorders of consciousness was completed to define MCS, develop diagnostic criteria for entry into MCS, and identify markers for emergence to higher levels of cognitive function.

RESULTS

There were insufficient data to establish evidence-based guidelines for diagnosis, prognosis, and management of MCS. Therefore, a consensus-based case definition with behaviorally referenced diagnostic criteria was formulated to facilitate future empirical investigation.

CONCLUSIONS

MCS is characterized by inconsistent but clearly discernible behavioral evidence of consciousness and can be distinguished from coma and VS by documenting the presence of specific behavioral features not found in either of these conditions. Patients may evolve to MCS from coma or VS after acute brain injury. MCS may also result from degenerative or congenital nervous system disorders. This condition is often transient but may also exist as a permanent outcome. Defining MCS should promote further research on its epidemiology, neuropathology, natural history, and management.

The infant who is visually unresponsive on a cortical basis

OBJECTIVE

To further explain cortical abnormalities in infants without visually guided behaviors with anatomically normal eyes by using a battery of objective visual tests and neuroimaging studies.

DESIGN

A cohort study.

PARTICIPANTS

Thirty-one infants with clear ocular media and normal fundi, who were visually unresponsive by clinical examination, and 31 control subjects.

METHODS

Full clinical examinations including Teller Acuity Cards (TAC) and developmental assessment. Infants with reduced acuities and/or developmental delay underwent pattern visual evoked potential (VEP) testing and brain neuroimaging studies. Eye movement recordings were done in individual infants.

MAIN OUTCOME MEASURES

Visual acuity, VEPs, eye movement recordings.

RESULTS

Infants were separated into two groups on the basis of being developmentally normal (DN) or developmentally delayed (DD). Fourteen DN infants had normal acuities for age and three of three infants had normal VEPs. On the basis of having normal visual function, these infants were considered to have visual inattention (VI). Sixteen DD infants had acuities ranging from normal to no visual orienting to the low vision TAC. All 16 DD infants had abnormal VEPs and abnormal neuroimaging studies (brain computed tomography, magnetic resonance imaging, or both) or microcephaly. On the basis of having structural and functional abnormalities of the brain, these infants were diagnosed as having cortical visual impairment (CVI). One additional infant with DD failed to orient to TACs but had a normal VEP and normal magnetic resonance imaging. In this infant and two infants with CVI the inability to "fix and follow" was attributed completely or partially to an oculomotor apraxia (OMA), which was confirmed by eye movement recordings.

CONCLUSIONS

The infant who is visually unresponsive on a cortical basis has either VI or CVI. Infants with OMA can also seem to be visually unresponsive. These disorders can be delineated in infancy on the basis of developmental status and a unique set of responses to visual acuity, VEPs, and oculomotor testing.

Methylenedioxymethamphetamine (MDMA; 'Ecstasy') suppresses antigen specific IgG2a and IFN-gamma production

Methylenedioxymethiamphetamine (MDMA; "Ecstasy") is a widely abused amphetamine derivative. In the present study, we examined the effect of acute MDMA administration on an antigen specific immune response. Responsiveness to an in vivo challenge with the soluble protein antigen keyhole limpet haemocyanin (KLH) was examined in rats following MDMA administration (2.5, 5 or 10 mg/kg; i.p.). KLH-specific serum IgM concentrations were measured 7 days following challenge, and serum IgG concentrations were measured 14 days following the KLH challenge. In addition, antigen-specific IFN-gamma and IL-6 production was measured in KLH-stimulated splenocytes. MDMA did not alter the KLH-specific IgM response. In contrast, MDMA (5 and 10 mg/kg) provoked a significant suppression of KLH-specific IgG production. Thus, MDMA administration did not alter the initial generation of the antibody response but rather inhibited antibody class switching from IgM to IgG. Two pathways for the genetic switch from IgM to IgG production were investigated. One pathway requires the Th(1) type cytokine IFN-gamma to stimulate IgM-secreting cells to switch to IgG(2a)-secreting cells. Another pathway requires the Th(2) type cytokines IL-4 and IL-6 to stimulate IgM-secreting cells to switch to IgG(1)-secreting cells. IgG(1) and IgG(2a) levels were measured to determine if these two pathways were differentially affected. The results indicate that only IgG(2a) levels were decreased following MDMA administration. Furthermore, this decrease in IgG(2a) was accompanied by decreased KLH-specific IFN-gamma production 14 days post KLH administration. In conclusion, these data indicate that MDMA alters the ability to switch from IgM to IgG(2a) production, possibly by reducing IFN-gamma. Potential health consequences for MDMA users are discussed.

Effect of orthognathic surgery on the temporomandibular joint in patients with anterior open bite

This study examined the prevalence of temporomandibular joint (TMJ) signs and symptoms in patients with anterior open bite. The influence of orthognathic surgery on the TMJ in these patients and the interaction of occlusal and psychologic variables on the presence and/or persistence of pain was studied. A retrospective survey of 83 patients with an anterior open bite who underwent orthognathic surgery was carried out. Records were examined for the prevalence of abnormal TMJ signs and symptoms, including pain. A survey was mailed to these patients that consisted of: (1) the TMJ Scale, (2) the Symptom Checklist 90 (SCL90), (3) the Spielberger State-Trait Anxiety Inventory (STAI), and (4) a visual analog scale on which patients indicated their degree of satisfaction with the procedure. Thirty-seven (42%) patients responded to the survey, and 13 (15%) also attended a clinical and radiographic examination. Multiple regression analysis was used for statistical analysis of the factors contributing to the presence and/or persistence of pain. In the preoperative group, the prevalence of pain was 32%, dysfunction 40%, and limitation of opening 7%. Age and gender were significantly associated with the presence of pain. The overall prevalence of abnormal TMJ signs and symptoms was not significantly different after orthognathic surgery. An abnormal psychologic profile was the most significant factor associated with the presence and/or persistence of pain. It is concluded that that the prevalence of temporomandibular disorders in anterior open bite patients increases with age, is significantly higher in females, and is not influenced by other occlusal variables. Furthermore, orthognathic surgery does not significantly influence temporomandibular disorders in patients with anterior open bite. Female patients, particularly those with an abnormal psychologic profile, are at a higher risk of persistent postoperative TMJ pain.

Lipopolysaccharide administration produces time-dependent and region-specific alterations in tryptophan and tyrosine hydroxylase activities in rat brain

The present study examined the effect of systemic administration of lipopolysaccharide (LPS; 100 and 250 microg/kg, i.p.) on tyrosine hydroxylase (TH) and tryptophan hydroxylase (TPH) activities in frontal cortex, striatum and midbrain of the rat. Enzyme activities were determined by measuring accumulation of the transient intermediates 5-hydroxytrptophan (5-HTP) and L-dihydroxyphenylalanine (L-DOPA) following in vivo administration of the decarboxylase inhibitor, NSD 1015. TPH activity was increased 2 hours after administration of LPS (100 and 250 microg/kg) in both frontal cortex and midbrain, and a secondary increase was seen in the midbrain 12 hours after challenge. LPS provoked an increase in TH activity in the midbrain only, and this was evident for up to 24 hours after LPS administration. Thus in addition to previous studies demonstrating that LPS increases in vivo NA, DA and 5-HT release, this study shows that LPS increases the activity of the rate-limiting enzymes responsible for their synthesis.

Beta-amyloid(1-42)-induced cholinergic lesions in rat nucleus basalis bidirectionally modulate serotonergic innervation of the basal forebrain and cerebral cortex

Ample experimental evidence suggests that beta-amyloid (A beta), when injected into the rat magnocellular nucleus basalis (MBN), impels excitotoxic injury of cholinergic projection neurons. Whereas learning and memory dysfunction is a hallmark of A beta-induced cholinergic deficits, anxiety, or hypoactivity under novel conditions cannot be attributed to the loss of cholinergic MBN neurons. As mood-related behavioral parameters are primarily influenced by the central serotonergic system, in the present study we investigated whether A beta(1-42) toxicity in the rat MBN leads to an altered serotonergic innervation pattern in the rat basal forebrain and cerebral cortex 7 days postsurgery. A beta infusion into the MBN elicited significant anxiety in the elevated plus maze. A beta toxicity on cholinergic MBN neurons, expressed as the loss of acetylcholinesterase-positive cortical projections, was accompanied by sprouting of serotonergic projection fibers in the MBN. In contrast, the loss of serotonin-positive fiber projections, decreased concentrations of both serotonin and 5-hydroxyindoleacetic acid, and decline of cortical 5-HT(1A) receptor binding sites indicated reduced serotonergic activity in the somatosensory cortex. In conclusion, the A beta-induced primary cholinergic deficit in the MBN and subsequent cortical cholinergic denervation bidirectionally modulate serotonergic parameters in the rat basal forebrain and cerebral cortex. We assume that enhanced serotonin immunoreactivity in the damaged MBN indicates intrinsic processes facilitating neuronal recovery and cellular repair mechanisms, while diminished cortical serotonergic activity correlates with the loss of the subcortical cholinergic input, thereby maintaining the balance of neurotransmitter concentrations in the cerebral cortex.

The virtual retinal display as a low-vision computer interface: a pilot study

This pilot study examined the performance of an alternative computer visual interface, the Virtual Retinal Display (VRD), for low-vision use. The VRD scans laser light directly onto the retina, creating a virtual image. Since visually impaired individuals can have difficulty using computer displays, a matched comparison study was done between the VRD and the standard cathode ray tube (CRT) monitor. Reading speed and acuity tests were collected from 13 low-vision volunteers selected to represent the broad range of partially sighted individuals actively involved in the work force. Forty-six percent of subjects had highest visual acuity while viewing the VRD; 30% of subjects had highest acuity viewing the CRT; and 24% of subjects had equal acuity across the two displays. Although mean reading speed across all 13 subjects indicated no significant difference between displays, individual subjects with predominantly optical causes of low vision exhibited clinically important increases in reading speed versus the CRT. However, most subjects with predominantly retinal damage showed a slight disadvantage using the VRD. We give theoretical explanation to the bifurcated results and conclude that for a subset of low-vision users, the VRD technology is very promising as a basis for future low-vision aids.

Methylenedioxymethamphetamine-induced suppression of interleukin-1beta and tumour necrosis factor-alpha is not mediated by serotonin

The purpose of the present study was to examine the role of serotonin release in methylenedioxymethamphetamine (MDMA)-induced immunosuppression in rats. We examined the effect of pretreatment with the selective serotonin reuptake inhibitor paroxetine, and the tryptophan hydroxylase inhibitor para-chlorophenylalanine on MDMA-induced suppression of interleukin-1beta and tumour necrosis factor (TNF)-alpha secretion following an in vivo lipopolysaccharide challenge. Although paroxetine blocked MDMA-induced serotonin depletion in the cortex and hypothalamus, it failed to alter the suppressive effect of MDMA on lipopolysaccharide-induced TNF-alpha secretion. Similarly, although para-chlorophenylalanine caused a 90% depletion in cortical and hypothalamic serotonin content, it failed to alter the suppressive effect of MDMA on lipopolysaccharide-induced interleukin-1beta or TNF-alpha secretion. In conclusion, although MDMA is a potent releaser of serotonin, the suppressive effects of MDMA on lipopolysaccharide-induced proinflammatory cytokine secretion cannot be attributed to its serotonin-releasing properties.

Behavioural, hyperthermic and neurotoxic effects of 3,4-methylenedioxymethamphetamine analogues in the Wistar rat

1. The ability of N-ethyl (MDEA) and N-butyl (MDBA) analogues of 3,4-methylenedioxymethamphetamine (MDMA, 'Ecstasy') to induce acute behavioural changes and increases in body temperature, and to cause serotonergic neurotoxicity, was assessed in young adult male Wistar rats. The in vitro ability of MDMA analogues to evoke presynaptic monoamine release from crude rat forebrain synaptosomal preparations pre-labelled with [3H]5-HT or [3H]DA was also measured. 2. In behavioural experiments, acute MDMA and MDEA (20 mg/kg, i.p.) significantly increased rat open-field locomotion scores, decreased open-field rearing, and induced stereotypy, Straub tail and head weaving. MDBA did not produce any of these behaviours. 3. After repeated dosing (8 x 20 mg/kg, i.p., twice daily for 4 days), MDMA > MDEA >> MDBA > or = saline at decreasing forebrain [3H]paroxetine binding levels and concentrations of 5-HT and 5-HIAA at 14 days post-treatment. None of the analogues caused any long-term changes in dopamine or noradrenaline concentrations in the forebrain. 4. Acute MDMA and MDEA (20 mg/kg, i.p.) produced significant acute increases in rat aural temperature compared with saline-treated animals, while 20 mg/kg MDBA caused no significant effects. 5. MDA, MDMA and MDEA were equipotent at inducing [3H]5-HT release from frontal cortex/hippocampal synaptosomes, while MDBA only evoked a significant release at 100 microM concentrations. The potency order for inducing [3H]DA release from striatal synaptosomes was MDA > MDMA > MDEA = MDBA. 6. This study shows that large N-alkyl substitution decreases the ability of MDMA analogues to evoke presynaptic 5-HT and DA release, induce acute hyperthermia, hyperlocomotion and behavioural changes, and cause long-term serotonergic neurotoxicity. 7. The structure-activity relationship data presented here indicate that the neurotoxic damage caused by substituted amphetamines requires a combination of acute hyperthermia and increased neurotransmitter release. Induction of one of these effects in isolation is not sufficient to cause serotonergic nerve terminal degradation.

Effects of reboxetine and sertraline treatments alone and in combination on the binding properties of cortical NMDA and beta1-adrenergic receptors in an animal model of depression

Changes to the binding properties of cortical N-methyl-D-aspartic acid (NMDA) and beta-adrenergic receptors have both been reported as potential indicators of antidepressant activity. In the present investigation we examined the effects of the noradrenaline reuptake inhibitor, reboxetine, the serotonin reuptake inhibitor, sertraline, alone and in combination on the binding properties of cortical NMDA receptors and cortical beta1-adrenoceptors following 14 days of treatment in the olfactory bulbectomized rat model of depression. A decrease in the potency of glycine to displace the strychnine insensitive glycine antagonist [3H] 5,7 dichlorokynurenic acid (5,7 DCKA) was observed in cortical homogenates of OB rats when compared to sham-operated controls. Similarly, treatment with the combination of reboxetine and sertraline for 14 days produced a decrease in the potency of glycine when compared to vehicle treated controls. By contrast neither olfactory bulbectomy or drug treatment significantly altered basal or glycine enhanced binding of the non-competitive NMDA antagonist [3H] MK-801 in cortical homogenates. Reboxetine alone, and in combination with sertraline, down-regulated [3H]-CGP 12177 (a selective beta-adrenoceptor antagonist) binding in both OB and sham-operated animals. The lack of a bulbectomy effect in the [3H] CGP-12177 binding assay, and the fact that olfactory bulbectomy and antidepressant treatments produce a similar change to the potency of glycine at the NMDA receptor, suggests that these tests do not provide a neurochemical marker for either the behavioral hyperactivity deficit or antidepressant response in the model.

Modulation of MK-801-induced behaviour by noradrenergic agents in mice

RATIONALE

Inhibition of glutamatergic N-methyl-D-aspartate (NMDA) receptors following the administration of NMDA receptor antagonists results in psychotic-like behaviour. Whereas it is known that pharmacological manipulation of dopaminergic and serotonergic pathways affect this drug-induced psychosis, a role for noradrenaline has not yet been clearly defined.

OBJECTIVES

Thus, in the present study, we assessed a possible role for noradrenaline in the behavioural response to the non-competitive NMDA receptor anatgonist, MK-801, in male CD-I mice.

RESULTS

MK-801 (0.02-1.28 mg/kg; ED50 0.2 mg/kg; s.c.) induced a dose-dependent increase in locomotor, stereotypic and ataxic behaviours. Pre-treatment with the noradrenaline re-uptake inhibitors, desipramine (10 mg/kg; i.p.) and reboxetine (20 mg/kg; i.p.), attenuated the locomotor, stereotypic and ataxic response to MK-801 (0.2 mg/kg; s.c.). The noradrenergic system was lesioned with N-(2-chloroethyl)-N-ethyl-2-bromobenzylamine hydrochloride (DSP-4, 50 mg/kg; i.p., 7 and 4 days prior to challenge) to reduce noradrenaline concentrations in the cortex by 70%-80%. Whereas DSP-4 lesioning had little effect on the response to MK-801, it completely reversed the attenuating effects of reboxetine. Pre-treatment with the alpha2 adrenoceptor agonist, clonidine (0.2 mg/kg; i.p.), and the antagonist, yohimbine (2 mg/kg; i.p.), attenuated and potentiated the response to MK-801, respectively. Pre-treatment with the alpha1 adrenoceptor antagonist, prazosin (2 mg/kg; i.p.), reduced the MK-801-induced response.

CONCLUSIONS

It therefore appears that presynaptic noradrenergic alpha2 and postsynaptic alpha1 adrenoceptor stimulation exert opposing effects on the behavioural expression of MK-801 in mice.

Concussion in sports and recreation

More than 800 sports-related concussions occur in the United States each day, sometimes involving high-profile athletes whose injuries reach public awareness through sports broadcasts and news media. Although nonphysicians are often present and relied upon for the detection of concussion in the sports setting, the proper diagnosis and management of this neurological problem require a physician's thoughtful attention to the athlete's signs and symptoms. This article offers a diagnostic protocol and treatment recommendations as well as a useful grading scale and management strategy for return to competition.

Prior exposure to methylenedioxyamphetamine (MDA) induces serotonergic loss and changes in spontaneous exploratory and amphetamine-induced behaviors in rats

The substituted amphetamine 3,4 methylenedioxyamphetamine (MDA) is a popular recreational drug of abuse. Administration of MDA to experimental animals has been shown to induce damage to serotonergic axons and nerve terminals. However, there is a lack of information on whether these treatments can produce any long-term changes in behavioural performance particularly under stressful conditions. In the present study, MDA (7.5 mg/kg; i.p.) was administered twice daily to adult male Sprague Dawley rats for four days. Four weeks following the last dose, spontaneous behaviors of these animals were tracked and scored in a novel "open field" environment using an automated video registration and computer interpretation system. Changes in behavior were observed in MDA treated animals including reductions in exploratory oriented behaviors (locomotion and rearing) and increases in grooming behavior when compared to vehicle treated controls. MDA-treated animals also displayed an enhanced locomotor and stereotyped response to d-amphetamine (12 mg/kg; i.p.). Significant reductions in 5-HT concentrations (20-30%) were observed in the frontal cortex, amygdala, striatum, and hypothalamus as a result of MDA treatment. In addition, [3H] paroxetine binding was reduced by (40%) in the cortex of MDA treated rats indicating that the decrease in 5-HT concentrations were accompanied by a reduction in intact presynaptic 5-HT nerve terminals. Changes in behavioural performance in a novel "open field" environment and following d-amphetamine challenge might be considered as a behavioural model of serotonergic deficit induced by MDA. The findings of this study also suggest that MDA use may increase both the abuse potential, and the propensity to develop psychosis as a result of abusing other psychostimulants such as d-amphetamine.

The toxicity profile of a single dose of paroxetine: an alternative approach to acute toxicity testing in the rat

In this study we have examined the effect of a single administration of the selective serotonin reuptake inhibitor, paroxetine (120-300 mg kg(-1), orally) in a recently developed rodent model of acute toxicity testing. Reduced body-weight, food consumption, water consumption and body temperature were observed in all paroxetine-treated groups, which were reversible within 7 days. Five days after administration, a dose-dependent increase in red blood cells, haemoglobin and haematocrit was observed with the 3 higher dose levels of paroxetine, which was significant in the 240 and 300 mg kg(-1) treatment groups (P < 0.05). Hyperactivity was apparent in the first 24 hr following treatment, as was evidence of the serotonin syndrome. When the animals were sacrificed (11 days after drug administration), an increase in liver weight was observed in the highest dose. These results are in agreement with those previously observed with paroxetine at the preclinical and clinical levels. They demonstrate that this rodent model, because of its multi-parameter nature, is a useful method for examining the consequences of a single high dose of an antidepressant drug.

Acetylsalicylic acid and other salicylates in relation to Stevens-Johnson syndrome and toxic epidermal necrolysis

AIMS

Various nonsteroidal anti-inflammatory drugs are known to increase the risk of Stevens-Johnson syndrome and toxic epidermal necrolysis. The relationship between salicylate treatment and these conditions is not known.

METHODS

A case-control study was conducted in four countries in Europe from 1989 to 1995.

RESULTS

Among 373 cases and 1720 controls, the multivariate relative risk estimate for any salicylate use in the previous week was 1.3 (95% confidence interval, 0.8-2.2); no statistically significant elevations were observed for single ingredient preparations or for salicylate-containing combination products.

CONCLUSIONS

Acetylsalicylic acid and other salicylates are not associated with a measurable increase in the risk of these rare but severe reactions.

Toward an understanding of violence: neurobehavioral aspects of unwarranted physical aggression: Aspen Neurobehavioral Conference consensus statement

OBJECTIVE

Violence is a global problem that poses a major challenge to individuals and society. This document is a consensus statement on neurobehavioral aspects of violence as one approach to its understanding and control.

BACKGROUND

This consensus group was convened under the auspices of the Aspen Neurobehavioral Conference, an annual consensus conference devoted to the understanding of issues related to mind and brain. The conference is supported by the Brain Injury Association and by individual philanthropic contributions. Participants were selected by conference organizers to represent leading opinion in neurology, neuropsychology, psychiatry, trauma surgery, nursing, evolutionary psychology, medical ethics, and law.

METHODS

A literature review of the role of the brain in violent behavior was conducted and combined with expert opinion from the group. The major goal was to survey this field so as to identify major areas of interest that could be targeted for further research. Additional review was secured from the other attendees at the Aspen Neurobehavioral Conference.

RESULTS

The group met in the spring of 1998 and 1999 for two 5-day sessions, between which individual assignments were carried out. The consensus statement was prepared after the second meeting, and agreement on the statement was reached by participants after final review of the document.

CONCLUSIONS

Violence can result from brain dysfunction, although social and evolutionary factors also contribute. Study of the neurobehavioral aspects of violence, particularly frontal lobe dysfunction, altered serotonin metabolism, and the influence of heredity, promises to lead to a deeper understanding of the causes and solution of this urgent problem.

Methylenedioxymethamphetamine (MDMA; Ecstasy) suppresses IL-1beta and TNF-alpha secretion following an in vivo lipopolysaccharide challenge

In this study we examined the effects of methylenedioxymethamphetamine (MDMA) administration on responsiveness to an in vivo immune challenge with lipopolysaccharide (LPS; 100 microg/kg; i.p.). LPS produced an increase in circulating IL-1beta and TNF-alpha in control animals. MDMA (20 mg/kg; i.p.) significantly impaired LPS-induced IL-1beta and TNF-alpha secretion. The suppressive effect of MDMA on IL-1beta secretion was transient and returned to control levels within 3 hours of administration. In contrast, the MDMA-induced suppression of TNF-alpha secretion was evident for up to 12 hours following administration. In a second study we examined the effect of co-administration of MDMA (5, 10 and 20 mg/kg; i.p.) on LPS-induced IL-1beta and TNF-alpha secretion, and demonstrated that all three doses potently suppressed LPS-induced TNF-alpha secretion, but only MDMA 10 and 20 mg/kg suppressed LPS-induced IL-1beta secretion. In addition, serum MDMA concentrations displayed a dose-dependent increase, with the concentrations achieved following administration of 5 and 10 mg/kg being in the range reported in human MDMA abusers. In order to examine the possibility that the suppressive effect of MDMA on IL-1beta and TNF-alpha could be due to a direct effect of the drug on immune cells, the effect of in vitro exposure to MDMA on IL-1beta and TNF-alpha production in LPS-stimulated diluted whole blood was evaluated. However IL-1beta or TNF-alpha production were not altered by in vitro exposure to MDMA. In conclusion, these data demonstrate that acute MDMA administration impairs IL-1beta and TNF-alpha secretion following an in vivo LPS challenge, and that TNF-alpha is more sensitive to the suppressive effects of MDMA than is IL-1beta. However the suppressive effect of MDMA on IL-1beta and TNF-alpha could not be attributed to a direct effect on immune cells. The relevance of these findings to MDMA-induced immunomodulation is discussed.

Development of chromatic and luminance detection contours using the sweep VEP

This study measured the development of contrast-sweep VEP thresholds to a range of chromatic and luminance stimuli. Subjects were 14-32 week-old infants (n=21) and three adults. Stimuli were 1 c/d sine gratings reversed at 5.6 Hz. Chromaticity was varied from the L-M axis to an achromatic axis. VEP thresholds when plotted in L- and M-cone contrasts showed that: (1) VEP thresholds did not consistently locate the psychophysical isoluminance match under the same stimulus conditions; (2) About 50% of the data were described by independent chromatic and luminance mechanism, however, thresholds were limited by the cone contrast of the stimulus, phase cancellation between visual mechanisms, and the proper sampling of thresholds in L- and M-cone contrast space and; (3) No significant changes occurred in VEP detection contours across ages but suprathreshold VEP amplitudes suggested complex developmental changes. Data from previous studies showed similar results.

Varying responses to the rat forced-swim test under diurnal and nocturnal conditions

The paradox that experiments in behavioural pharmacology employing nocturnal rodent species are carried out almost exclusively in the resting phase of the animals' circadian cycle has remained largely unexamined and unquestioned. This is despite the fact that all major physiological systems in the body are intrinsically aligned with its natural circadian rhythm. The forced-swim test (FST) is a rodent model that is used extensively as a screening test for antidepressant activity. The objectives of the present study were to examine the behaviour of rats in the FST under diurnal and nocturnal conditions and, in addition, to profile the response of neurochemical, neuroendocrine, and cellular indices of stress at time points up to 120 min following exposure to the FST. The time spent in escape-oriented activity was significantly less when animals were tested in the dark phase. The profile of serum corticosterone and adrenal ascorbic acid concentrations indicates that the animals were less stressed by the test situation during the active (i.e., dark) phase of their circadian cycle. Similarly, increases in blood enzymatic markers of stress-induced cellular damage were less marked following FST exposure in the nocturnal period. Characteristic stress-induced increases in 5-HT turnover in the frontal cortex and amygdala observed in the diurnal phase were reversed in the nocturnal period. In conclusion, circadian differences in behaviour in the FST may be related to parallel alterations in the ability of animals to adapt to exposure to stress.

Effect of subchronic antidepressant treatments on behavioral, neurochemical, and endocrine changes in the forced-swim test

The purpose of the present study was to examine the effect of subchronic treatment (24 days) with antidepressants displaying differential effects on noradrenaline and serotonin reuptake, on behavior, neurochemistry, and hypothalamic-pituitary-adrenal (HPA) axis activity following FST exposure in the rat. Desipramine (7.5 mg/kg, IP) significantly decreased immobility in the FST, whilst paroxetine (7.5 mg/kg IP) and venlafaxine (10 mg/kg, IP) were without effect. Nonetheless, treatment with all three antidepressants significantly attenuated stress-related increases in amygdaloid and cortical serotonin turnover. Of the three antidepressants examined, only desipramine attenuated the stress-associated elevation in serum corticosterone. In conclusion, although FST-induced increases in serotonin turnover in the frontal cortex and amygdala were attenuated following treatment with all three antidepressants, FST-induced behavioral changes and increased HPA axis activity were normalized only following desipramine treatment. In addition, these results suggest that neurochemical mechanisms independent of increased serotonergic activity subserve the normalization of behavior and HPA axis responses in the FST. These data also add to our understanding of the interactions between antidepressants and stress-induced behavioral, neurochemical, and endocrine alterations, and illustrates important differences between classes of antidepressants.

Characterization of D-fenfluramine-induced hypothermia: evidence for multiple sites of action

The effects of D-fenfluramine on core body temperature has been largely investigated under conditions of either high or low ambient temperature, whereas little research has focused on this response under normal environmental conditions. Moreover, there has been neglect in research on the mechanisms underlying changes in body temperature. In this study, we demonstrate that D-fenfluramine (5 and 10 mg/kg) induces a sustained decrease in body temperature in the rat under normal ambient temperatures. Pre-treatment with the selective serotonin reuptake inhibitor sertraline (5 mg/kg), the full 5-HT(1A) receptor antagonist 4-fluoro-N-[2-[4-(2-methoxyphenyl)-1-piperazinyl]ethyl]-2-pyridinyl benzamide], WAY 100635 (0.15 mg/kg) and the 5-HT(2C) receptor antagonist benzofuran-2-carboxamidine, RO 43-0440 (2.5 mg/kg) blocked D-fenfluramine-induced hypothermia. Depletion of 5-hydroxytryptamine (5-HT) stores following treatment with the serotonergic neurotoxin parachlorophenylalanine reversed the initial hypothermic effects of D-fenfluramine but not the later effects, as D120 min post-challenge) in animals pre-treated with parachlorophenylalanine. Such findings are consistent with a requirement for D-fenfluramine uptake into 5-HT neurons followed by release of 5-HT from intracellular stores and stimulation of post-synaptic 5-HT receptors to reduce body temperature. The hypothermic response to D-fenfluramine was potentiated by ketanserin pre-treatment 30 min post-challenge but then antagonized at later time intervals. Pre-treatment with the dopamine, D(2) antagonist, haloperidol (1 mg/kg) and sulpiride (30 mg/kg) had a similar effect in blocking the hypothermia as WAY 100635, suggesting a role for dopamine D(2) receptors in the response. Pre-treatment with the alpha(2)-adrenoceptor antagonist yohimbine failed to block the hypothermic response. These results suggest multiple sites of action mediating D-fenfluramine-induced hypothermia and may be the result of a combined effect of D-fenfluramine and its active metabolite norfenfluramine affecting not only the release of 5-HT but also stimulation of post-synaptic receptors.

Test conditions influence the response to a drug challenge in rodents

These studies were conducted to examine the differential response to a drug challenge under varied experimental test conditions routinely employed to study drug-induced behavioral and neurophysiological responses in rodents. Apomorphine, a nonselective dopamine agonist, was selected due to its biphasic behavioral effects, its ability to induce hypothermia, and to produce distinct changes to dopamine turnover in the rodent brain. From such experiments there is evidence that characterization and detection of apomorphine-induced activity in rodents critically depends upon the test conditions employed. In rats, detection of apomorphine-induced hyperactivity was facilitated by a period of acclimatization to the test conditions. Moreover, test conditions can impact upon other physiological responses to apomorphine such as drug-induced hypothermia. In mice, apomorphine produced qualitatively different responses under novel conditions when compared to those behaviors elicited in the home test cage. Drug-induced gross activity counts were increased in the novel exploratory box only, while measures of stereotypic behavior were similar in both. By contrast, apomorphine-induced locomotion was more prominent in the novel exploratory box. Dopamine turnover ratios (DOPAC:DA and HVA:DA) were found to be lower in those animals exposed to the exploratory box when compared to their home cage counterparts. However, apomorphine-induced reductions in striatal dopamine turnover were detected in both novel and home cage environments. The implications of these findings are discussed with particular emphasis upon conducting psychopharmacological challenge tests in rodents.

Estimating risks for matching factors in case-control studies

Matching for factors such as age and sex is a convenient method for minimizing confounding in case-control studies, but it does not allow inferences about the effects of the matching factors unless case ascertainment is virtually complete and the distribution of the matching factors in the source population is known. When this is so, the effect of a particular factor can be estimated by comparing the population distribution of that factor with what is observed in the case series. Such a comparison, however, may itself be confounded by other factors that are related to both the matching factors and the disease under investigation. This article proposes a method for evaluating matching factors as risk factors, which uses information on the distribution of potential confounders in the reference series and exposure relative risk estimates to adjust the person-time proportionality constant in a Poisson regression model. The method is particularly suited to data sets in which many of the elementary matching strata contain few or no cases and/or controls. It makes use of standard analytic procedures, but requires the estimation of an additional variance-covariance component for the estimated Poisson regression coefficients. Further factors that may confound the relationship between exposure and disease are easily accommodated. The method is demonstrated in two examples: a matched case-control study of drugs in relation to the rare blood dyscrasia, agranulocytosis, that was conducted in Europe and Israel, and a case-control study of ovarian cancer in Australia.

An assessment of the acute effects of the serotonin releasers methylenedioxymethamphetamine, methylenedioxyamphetamine and fenfluramine on immunity in rats

The purpose of the present study was to examine the effect of the serotonin releasing amphetamine derivatives methylenedioxymethamphetamine (MDMA), methylenedioxyamphetamine (MDA) and fenfluramine (FEN) on immunity in rats. Similar to MDA and MDMA, FEN reduced the number of circulating lymphocytes, provoked a suppression of Con A-stimulated lymphocyte proliferation and total IFN-gamma and IL-10 production in diluted whole blood cultures. Thus the non-psychostimulant amphetamine derivative FEN, shares the ability of the psychostimulant methylenedioxy-substituted amphetamine derivatives to alter these indices of immune function in the rat. However, when Con A-stimulated cytokine production was normalised for the number of lymphocytes in culture in order to examine cytokine production at a cellular level, the effect of the amphetamine derivatives begins to diverge. FEN shares with MDMA and MDA the ability to suppress production of the Th2 type cytokine IL-10. However the effect of these drugs on Th1 type cytokine secretion was much more complex. While the methylendioxy-substituted amphetamines increases the secretion of the Th1 type cytokine IL-2 without altering the related Th1 type cytokine IFN-gamma, FEN did not alter IL-2 secretion, but suppressed IFN-gamma secretion. In addition to these effects on T-cell responses, all three drugs inhibited LPS-induced TNF-alpha secretion from diluted whole blood cultures suggesting that macrophage activity is impaired following treatment. In all, these data extend our previous findings concerning the effects of MDMA on the immune system and demonstrate that the related serotonin releasers MDA and FEN also provoke immunological changes in rats.

Olfactory bulbectomy provokes a suppression of interleukin-1beta and tumour necrosis factor-alpha production in response to an in vivo challenge with lipopolysaccharide: effect of chronic desipramine treatment

The olfactory bulbectomized (OB) rat has been developed as an animal model of depression and exhibits several behavioural and neurochemical characteristics that are qualitatively similar to those found in clinically depressed patients. In addition to the behavioural and neurochemical abnormalities seen in OB rats, it has been reported that these animals have alterations in a number ex vivo measures of immune function many of which are reversed following chronic antidepressant treatment. In the present study we sought to examine the effects of olfactory bulbectomy on responsiveness to an in vivo immune challenge with bacterial lipopolysaccharide (LPS; 100 microg/kg, i.p.). In addition, the effect of chronic treatment with the tricyclic antidepressant desipramine (7.5 mg/kg, i.p.) on bulbectomy related behavioural changes, hypothalamic-pituitary-adrenal axis activity and immune responsiveness was evaluated. To our knowledge this is the first time that in vivo immunological responsiveness has been examined in the OB rat model of depression. OB rats exhibited a characteristic hyperactive response in a novel 'open field' environment, which was attenuated following chronic desipramine treatment. LPS provoked a large increase in circulating interleukin (IL)-1beta and tumour necrosis factor (TNF)-alpha in vehicle treated sham operated animals. Vehicle treated OB rats displayed a significant impairment in LPS-induced IL-1beta (54%) and TNF-alpha (70%) secretion compared to their sham operated controls, an effect that was potentiated following chronic desipramine treatment. Furthermore, sham animals that were chronically treated with desipramine displayed decreases in LPS-provoked IL-1beta (51%) and TNF-alpha (49%) secretion compared to vehicle treated counterparts. In addition, LPS-induced alterations in corticosterone and adrenal ascorbic acid concentrations were also attenuated by bulbectomy, an effect that was further enhanced following chronic desipramine treatment. In conclusion, these data provide evidence that olfactory bulbectomy in the rat impairs the ability of macrophages to produce the proinflammatory cytokines IL-1beta and TNF-alpha following an in vivo challenge with bacterial LPS. Whilst chronic treatment with desipramine normalized the behavioural hyperactivity observed in OB rats, such treatment further impaired LPS-induced IL-1beta and TNF-alpha secretion in bulbectomized rats.

Acute toxicity profile of maprotiline in the rat

The aim of the present study was to examine the toxic effects of single oral administrations of the antidepressant maprotiline at 150 mg/kg or 300 mg/kg using female Sprague-Dawley rats. Body-weight gain was significantly reduced in the group receiving 300 mg/kg on days 1-5 of the study (P<0.01). A significant reduction in food and water intake was observed on days 1 and 2 of the study (P<0.01) in the 300 mg/kg group and on day 1 in the 150 mg/kg group (P<0.05). There was a significant decrease in nocturnal home cage activity over the first five days of the study in the 300 mg/kg group (P<0.01). A significant hypothermic response was observed in both 150 and 300 mg/kg groups at 1, 2 and 4 hr after dosing (P<0.01), that had returned to control values within 8 hr following administration. This study demonstrates that a multi-parameter approach is appropriate for the investigation of high doses of antidepressants in rodents.

Differential effect of chronic antidepressant treatments on lipopolysaccharide-induced depressive-like behavioural symptoms in the rat

In the present study we observed that lipopolysaccharide (LPS) administration provoked a characteristic reduction in body weight gain, food consumption, saccharin (but not water) consumption and nocturnal locomotor activity. It has been previously suggested that the ability of LPS to suppress the consumption of, and preference for, a palatable solution such as saccharin without altering water consumption, may represent an anhedonic response. The results of the present study demonstrate that chronic treatment with the tricyclic antidepressant (TCA) desipramine (7.5 mg/kg; i.p.) prevented LPS-induced anorexia, loss of body weight, the antidipsogenic effect and hypoactivity. In contrast, chronic treatment with the antidepressants paroxetine (7.5 mg/kg; i.p.) and venlafaxine (10 mg/kg; i.p.) failed to alter any of the LPS-induced behavioural responses. Furthermore, chronic treatment with desipramine (and to a lesser extent paroxetine) reduced the consumption of, and preference for, saccharin suggesting that these antidepressant treatments induce an "anhedonic" response in their own right. In conclusion, chronic desipramine treatment attenuated LPS-induced depressive-like behavioural symptoms in the rat. However, chronic treatment with paroxetine and venlafaxine did not significantly alter LPS-induced behavioural responses. The results of the present study support the hypothesis that TCA's may exert part of their anti-depressive efficacy through their effects on the immune system. However, this property does not appear to be shared by newer antidepressants which possess a better side effect profile than the TCA's. The suppressive effect of TCA's on proinflammatory cytokine secretion is discussed as a mechanism by which these agents alter LPS-induced behavioural responses.

Effects of acute injury characteristics on neuropsychological status and vocational outcome following mild traumatic brain injury

Despite recent attempts to define acute injury characteristics of mild traumatic brain injury (MTBI), neuropsychological outcome is often unpredictable. One hundred MTBI cases were prospectively collected, which were consecutive referrals to a concussion clinic, and the roles of various acute neurologic variables were examined in relation to neuropsychological status and vocational outcome. Significant differences were found between subgroups of patients classified by (1) mechanism of injury (i.e. acceleration/deceleration trauma in which the head strikes an object (HSO) versus acceleration/deceleration trauma in which the head does not strike an object (HNSO) versus trauma in which an object strikes the head (OSH), and (2) type of injury (i.e. motor vehicle collision, fall, assault, motor vehicle-pedestrian collision, falling object, sports/recreation). There was no difference, with respect to neuropsychological status or vocational outcome, between patients who had positive findings on computerized tomography (CT) versus those who were CT negative. Additionally, there was no difference between patients who had suffered brief loss of consciousness (LOC) and those without LOC. These findings suggest that selective acute injury characteristics may be used to classify subtypes of MTBI patients.

The risk of acute major upper gastrointestinal bleeding among users of aspirin and ibuprofen at various levels of alcohol consumption

OBJECTIVE

Major upper gastrointestinal bleeding (UGIB) is the most important adverse effect of aspirin and other nonsteroidal anti-inflammatory drugs (NSAIDs). Alcoholic beverages also precipitate UGIB. This analysis was conducted to evaluate whether the deleterious effects of NSAIDs are further increased among drinkers.

METHODS

An interview-based, case-control study was conducted in the U.S. and Sweden; 1224 patients hospitalized with acute major UGIB due to newly occurring peptic ulcer or gastritis were compared to 2945 neighbor controls.

RESULTS

Compared with those who drank less than one drink/wk, the relative risk of acute UGIB increased with increasing alcohol consumption, rising to 2.8 among those who drank > or = 21 drinks/wk. Among current drinkers, the relative risk of acute UGIB due to the use of aspirin was raised at all levels of alcohol consumption; the estimate for aspirin taken at least every other day (regular use) at doses of > 325 mg among all current drinkers combined was 7.0; for regular use at lower doses, the corresponding estimate was 2.8, and for any occasional use, it was 2.4. All estimates were statistically significant. Data for ibuprofen were more limited, but the relative risk estimates did not appear to vary consistently with level of alcohol consumption. For regular use (all doses combined), the estimate among all drinkers combined was significantly elevated, at 2.7; occasional ibuprofen use was not associated with UGIB (1.2). There were insufficient data to evaluate other NSAIDs according to alcohol consumption.

CONCLUSIONS

The findings suggest that acute UGIB is similarly associated with the use of the two most common nonprescription NSAIDs, aspirin and ibuprofen, at all levels of alcohol consumption. As heavy alcohol intake independently increases the risk, the incidence of UGIB is highest among persons who are both heavy drinkers and users of aspirin or ibuprofen.

Risk of breast cancer according to use of antidepressants, phenothiazines, and antihistamines

In laboratory studies, some antidepressants caused increased growth of mammary tumors. The relation of use of these drugs to the development of breast cancer was examined in a hospital-based case-control study. Information, including lifetime medication history, was collected by interview from 5,814 women with primary breast cancer diagnosed within the previous year, 5,095 women with primary malignancies of other sites, and 5,814 women with other conditions. Relative risks were estimated by using unconditional multiple logistic regression for regular use (> or =4 days per week for > or =4 weeks beginning > or =1 year before admission) of antidepressants and structurally similar drugs. With reference to never use of each drug, relative risks were statistically compatible with 1.0 for selective serotonin reuptake inhibitors (SSRI), tricyclics, other antidepressants, phenothiazines, and antihistamines; results were very similar using both control groups. There were no significant increases in risk for any category of regular use, stratified according to cumulative duration of use or time interval since the most recent use or for any individual drug within the broader classes. However, the estimate for regular SSRI use in the previous year, 1.8, was of borderline statistical significance (95% confidence interval: 1.0, 3.3). The findings do not support an overall association between the use of antidepressants, phenothiazines, or antihistamines and breast cancer. However, the results for SSRIs are not entirely reassuring.

Comparative effects of serotonergic agonists with varying efficacy at the 5-HT(1A) receptor on core body temperature: modification by the selective 5-HT(1A) receptor antagonist WAY 100635

A reduction in core body temperature is one of the characteristic consequences of 5-HT1A receptor activation in rodents. In this study, we characterized the hypothermic effects of four 5-HT1A receptor ligands with varying affinity and selectivity at the 5-HT1A receptor. 8-OH-DPAT and flesinoxan (full agonists); ipsapirone (selective partial agonist) and eltoprazine (non selective partial agonist), all induced a dose-dependent reduction in core body temperature, which was maximal 30 min subsequent to administration. This response differed quantitatively between the agonists, in both the extent and the duration of its effects. The selective 5-HT1A receptor antagonist WAY 100635 (0.15 mg/kg), attenuated the hypothermia induced by the partial agonists, ipsapirone (10 mg/kg) and eltoprazine (10 mg/kg). In contrast, the higher dose of WAY 100635 (1 mg/kg) antagonized the effects of all agonists. This study therefore further confirms the utility of hypothermia as a simple, robust in-vivo probe of 5-HT1A receptor function. This paradigm, which was enhanced by use of specific antagonists such as WAY 100635, may prove useful for the detection and characterization of novel 5-HT1A receptor ligands.

The effect of treatment with a new antidepressant, INN 00835, on platelet serotonin uptake in depressed patients

BACKGROUND

INN 00835 (4-fluoro-L-phenylalanyl-trans-4-hydroxy-L-prolyl-L-arginyl-glycyl-trypt ophanamide ditrifluoroacetate) is a synthetic pentapeptide antidepressant with a potential for rapid onset of action. We were interested to see if such action could be correlated with serotonin uptake by platelets.

METHODS

In a phase II clinical trial, unipolar depressed patients were administered active drug, INN 00835 or placebo, subcutaneously, at 0.2 mg/kg, once daily for 5 consecutive days. Efficacy of treatment was evaluated by psychometric tests (HAMD, MADS, CSRS, CGI and total VAS). Changes in platelet uptake rates of serotonin (3H-5HT) were measured in plasma from the patients participating in the phase II clinical trial, prior to and immediately after treatment with INN 00835 (19 patients) or placebo (16 patients), to evaluate the effect of treatment with INN 00835 on the rate of platelet 5-HT uptake.

RESULTS

The data evaluated by using the psychometric tests indicated a significant response to treatment with INN 00835 after 5 days of dosing. The rates of platelet 5-HT uptake were lower prior to treatment (baseline), and increased after the 5-day treatment period. The change in the uptake rate (deltaVmax) following treatment was significantly larger in the active group than in the placebo group (P < 0.05). The difference between the placebo group and the patients who responded to treatment was even larger.

LIMITATIONS

Small number of subjects.

CONCLUSION

The data tend to substantiate the use of platelet serotonin uptake as a biochemical marker of effective treatment of depression.

Differential effect of a single high dose of the tricyclic antidepressant imipramine on interleukin-1beta and tumor necrosis factor-alpha secretion following an in vivo lipopolysaccharide challenge in rats

Tricyclic antidepressants (TCAs) of which imipramine is one, are commonly used in the treatment of depressive disorders and other forms of psychiatric illness. There have been many reports regarding the suppressive effects of TCAs on immune function. However, information is still limited regarding the effects of TCAs on the immune system, as many of the studies conducted to date have concentrated on in vitro exposure to such drugs, or ex vivo measures of immunity following drug administration. Thus in the present investigation, an in vivo challenge with bacterial lipopolysaccharide (LPS) (100 microg/kg; i.p.) was used to assess immunocompetence following administration of a single high dose of the TCA, imipramine (100 mg/kg, p.o.). The results demonstrated that imipramine pretreatment inhibits LPS-induced increases in serum concentrations of the proinflammatory cytokine, tumor necrosis factor (TNF)-alpha both 3 and 6 h, following administration. However, LPS-induced interleukin (IL)-1beta secretion was not significantly altered following imipramine treatment at either of the timepoints examined. In addition, serum concentrations of corticosterone and the antiinflammatory cytokine IL-10 were measured, and imipramine treatment failed to alter either basal, or LPS-induced increases in these immunosuppressive agents. In conclusion, although IL-1beta and TNF-alpha are both macrophage-derived proinflammatory cytokines, the present study demonstrates a differential sensitivity of these cytokines to the suppressive effects of the TCA imipramine. Furthermore, the suppressive effects of imipramine on LPS-induced TNF-alpha secretion could not be attributed to either increased glucocorticoid levels, or increased secretion of the antiinflammatory cytokine IL-10. The relevance of these findings to antidepressant-induced immunotoxicity are discussed.

Reboxetine attenuates forced swim test-induced behavioural and neurochemical alterations in the rat

The forced swim test is a behavioural paradigm that is predicative of antidepressant activity in rodents. Until recently, research has focused on the ability of antidepressant drugs to decrease immobility in the forced swim test paradigm, but the neurochemical sequelae induced by swim stress, or the neurochemical basis of antidepressant-induced behavioural changes have received little attention. In this regard, we have recently demonstrated that forced swim test exposure increases serotonergic activity in the amygdala, frontal cortex and hippocampus and dopamine turnover in the striatum. In addition, forced swim test-exposure activates the hypothalamic pituitary adrenal axis. The purpose of the present study was to examine the effect of treatment with the selective noradrenaline reuptake inhibitor reboxetine (3, 10 and 30 mg/kg; i.p.) on immobility and defaecation scores in the forced swim test, and on forced swim test-induced neurochemical and hypothalamic pituitary adrenal axis changes in the rat. Reboxetine treatment (10 and 30 mg/kg) significantly decreased immobility and defaecation in the forced swim test in dose dependent manner. Furthermore, reboxetine produced a dose dependent attenuation of forced swim test-induced increases in serotonin turnover in the amygdala and frontal cortex and dopamine turnover in the striatum. Reboxetine (30 mg/kg) produced a modest, but non-significant, attenuation of forced swim test-induced increases in serum corticosterone concentrations. These data demonstrate that, in addition to the behavioural activity of reboxetine in the rat forced swim test paradigm, a dose-dependent attenuation of swim stress-induced increases in serotonergic and dopaminergic activity occurred in a region specific manner. These are the first data to demonstrate that treatment with the selective noradrenaline reuptake inhibitor, reboxetine can impact on the activity of other neurotransmitter systems in response to stress. Moreover, these data further demonstrate that this paradigm is a valuable tool in studying the effect of antidepressants, on both behaviour and swim stress-related alterations in central neurotransmitter function and hypothalamic pituitary adrenal axis activity in the rat.

Metyrapone displays antidepressant-like properties in preclinical paradigms

A possible involvement of glucocorticoids in the aetiology of depression is suggested by commonly reported hypothalamo-pituitary-adrenocortical (HPA) axis abnormalities in depressed patients, the modulation of the HPA axis by antidepressant drugs and clinical reports of antidepressant efficacy with antiglucocorticoid agents. The effects of treatment with metyrapone, a glucocorticoid synthesis inhibitor, and the tricyclic antidepressant, desipramine, in two rodent models of depression, namely the forced swim test and olfactory bulbectomized (OB) rat, were investigated. In addition, the effect of chronic metyrapone and desipramine treatments on the hypothermic response to a challenge with the 5-HT1A agonist, 8-hydroxy-2-(di-n-propylamino) tetralin (8-OH-DPAT) was assessed. There is experimental evidence to suggest that attenuation of the hypothermic response to this agonist occurs following chronic antidepressant treatment. In the forced swim test, metyrapone (50 mg/kg) and desipramine (10 mg/kg) significantly reduced the immobility time. In the olfactory bulbectomized rat model of depression, chronic administration (14 days) of metyrapone (50 mg/kg b.i.d.) and desipramine (5 mg/kg b.i.d.) attenuated the OB-related hyperactivity in a novel stressful environment. Chronic metyrapone treatment (50 mg/kg b.i.d.) attenuated the hypothermic response to an acute challenge with 8-OH-DPAT (0.05 mg/kg s.c.), indicating a change to the sensitivity of 5-HT1A receptors. These preclinical tests demonstrate an antidepressant-like profile for metyrapone. Further exploration of the therapeutic potential and possible mechanism of action of glucocorticoid antagonism in depression is warranted.