A latent class analysis of mental disorders, substance use, and aggressive antisocial behavior among Swedish forensic psychiatric patients.

BACKGROUND: Patients in the forensic mental health services (FMHS) with a mental disorder, a co-occurring substance use disorder (SUD), and high risk of aggressive antisocial behavior (AAB) are sometimes referred to as the 'triply troubled'. They suffer poor treatment outcomes, high rates of criminal recidivism, and increased risk of drug related mortality. To improve treatment for this heterogeneous patient group, more insight is needed concerning their co-occurring mental disorders, types of substances used, and the consequent risk of AAB. METHODS: A three-step latent class analysis (LCA) was used to identify clinically relevant subgroups in a sample of patients (n = 98) from a high-security FMHS clinic in Sweden based on patterns in their history of mental disorders, SUD, types of substances used, and AAB. RESULTS: A four-class model best fit our data: class 1 (42%) had a high probability of SUD, psychosis, and having used all substances; class 2 (26%) had a high probability of psychosis and cannabis use; class 3 (22%) had a high probability of autism and no substance use; and class 4 (10%) had a high probability of personality disorders and having used all substances. Both polysubstance classes (1 and 4) had a significantly more extensive history of AAB compared to classes 2 and 3. Class 3 and class 4 had extensive histories of self-directed aggression. CONCLUSIONS: The present study helps disentangle the heterogeneity of the 'triply troubled' patient group in FMHS. The results provide an illustration of a more person-oriented perspective on patient comorbidity and types of substances used which could benefit clinical assessment, treatment planning, and risk-management among patients in forensic psychiatric care.

Implementing clinical guidelines for co-occurring substance use and major mental disorders in Swedish forensic psychiatry: An exploratory, qualitative interview study with mental health care staff.

INTRODUCTION: Patients with substance use disorders (SUD) and co-occurring mental disorders (COD) within forensic psychiatric care often suffer poor treatment outcomes and high rates of criminal recidivism, substance use, and psychiatric problems. This study aimed to describe the conditions for, and mental health care staff's experiences with, implementing integrated SUD-focused clinical guidelines, including assessment and treatment for patients with COD at a high-security forensic mental health services (FMHS) facility in Sweden. METHODS: Study staff conducted nineteen semi-structured interviews with health care staff experienced in administering the new SUD assessment and treatment. The study conducted a thematic analysis to describe the health care staff's experiences with these guidelines and suggestions for improvement. RESULTS: Most participants reported appreciation for the implementation of clinical guidelines with an SUD focus, an area they considered to have previously been neglected, but also noted the need for more practical guidance in the administration of the assessments. Participants reported the dual roles of caregiver and warden as difficult to reconcile and a similar, hindering division was also present in the health care staff's attitudes toward SUD. Participants' reports also described an imbalance prior to the implementation, whereby SUD was rarely assessed but treatment was still initiated. One year after the implementation, an imbalance still existed, but in reverse: SUD was more frequently assessed, but treatment was difficult to initiate. CONCLUSIONS: Despite indications of some ambivalence among staff regarding the necessity of the assessment and treatment guidelines, many participants considered it helpful to have a structured way to assess and treat SUD in this patient group. The imbalance between frequent assessment and infrequent treatment may have been due to difficulties transitioning patients across the "gap" between assessment and treatment. To bridge this gap, mental health services should make efforts to increase patients' insight concerning their SUD, flexibility in the administration of treatment, and the motivational skills of the health care staff working with this patient group. Participants considered important for enhancing treatment quality a shared knowledge base regarding SUD, and increased collaboration between different professions and between in- and outpatient services.

Characterization of MK-801-induced behavior as a putative rat model of psychosis.

The objective of this study was to characterize the behavior induced by the N-methyl-D-aspartate receptor antagonist MK-801 (dizocilpine maleate) in rats as a model of psychosis. The temporal profile, dose dependence, age, and sex differences of the behavior are described. A gas chromatographic method for the analysis of MK-801 in plasma and brain was developed. Female rats showed 4 to 10 times more MK-801-induced behavior and displayed around 25 times higher serum and brain concentrations of MK-801 than male rats. Twenty-one neuroactive compounds, including a number of excitatory amino acid-active substances, were tested for the effect on MK-801-induced behavior. Neuroleptics blocked MK-801-induced behavior in a dose-dependent manner that correlated to their antipsychotic potency in humans. Adenosine receptor agonists and an N-methyl-D-aspartate receptor-associated glycine site antagonist showed putative antipsychotic effects. In conclusion, MK-801-induced behavior represents a rat excitatory amino acid hypofunction model of psychosis that appears to be of clinical relevance and may be of value in the search for new antipsychotic agents.

Successful use of a selective serotonin reuptake inhibitor in a patient with multiple chemical sensitivities.

A 53-year-old man with multiple chemical sensitivities (MCS) received the selective serotonin reuptake inhibitor (SSRI) citalopram for treatment of depression. The treatment was successful and, in parallel to the remission of the depressive symptoms, all MCS symptoms vanished. This suggests that a subgroup of MCS patients may have an atypical depression, that they should be psychiatrically evaluated, and that antidepressive pharmacological treatment may be considered in cases of MCS.

Effects of the 21-amino steroid tirilazad mesylate (U-74006F) on brain damage and edema after perinatal hypoxia-ischemia in the rat.

Using 7-d-old rat pups, the neuroprotective efficacy of the lipid peroxidation inhibitor tirilazad mesylate (U-74006F) was tested in a model of perinatal hypoxic-ischemic (HI) brain damage. The experimental protocol was divided into five parts: 1) pre- plus post-HI treatment or 2) only post-HI treatment with tirilazad (7.5 mg/kg intraperitoneally) or vehicle with evaluation of hemispheric weight deficit 14 d after the insult; 3) post-HI treatment with tirilazad or vehicle with histopathologic evaluation 14 d after the insult; 4) pre- plus post-HI treatment; or 5) posthypoxic treatment with tirilazad or vehicle with evaluation of brain edema 20 h after the insult. In the pre- plus post-HI treatment group, the mean left hemispheric weight deficit was 20.7% +/- 17.8 (mean +/- SD) in tirilazad-treated rats and 27.5% +/- 20.4 in vehicle-treated rats (p = 0.032). Corresponding values for the post-HI treated animals were 19.6% +/- 16.0 and 28.6% +/- 15.4 (p = 0.043). Histopathologic injury assessed as pathology score on a scale of 0-5 was less extensive in tirilazad-treated animals compared with controls (p = 0.038). There was a significant increase in water content in the HI hemisphere compared with the contralateral (hypoxic) hemispheres in tirilazad- and vehicle-treated animals. This increase of water content in the HI hemispheres did not differ between tirilazad- and vehicle-treated animals. The lipid peroxidation inhibitor tirilazad administered after perinatal HI reduced brain damage by 30%, but no effect was found on early postinsult edema.

The effect of anosmia on MK-801-induced behaviour in mice.

Systemic administration of N-methyl-D-aspartate (NMDA) receptor antagonists induces a well defined behaviour in rodents characterized by, for example increased locomotion and ataxia. It is not clear in what brain region(s) NMDA antagonists induce this behaviour. We have studied the possible involvement of olfactory pathways by making adult mice anosmic via intranasal injection of zinc sulphate, a procedure that is known to destroy the olfactory epithelium. The NMDA antagonist MK-801 was given intraperitoneally (0.1-1.0 mg/kg) and the animals were scored for locomotion and ataxia 60-90 min later. Before MK-801 administration, olfactory-lesioned mice did not differ from non-lesioned controls with regard to locomotion or ataxia. MK-801 caused locomotor activation (> or = 0.2 mg/kg) and ataxia (> or = 0.5 mg/kg) in both groups. In general, olfactory-lesioned animals showed more locomotion and less ataxia after MK-801 administration than non-lesioned animals. Lesioned animals displayed 2.0- (P < 0.05) and 3.7-fold (P < 0.05) more extensive locomotor activation than non-lesioned animals after 0.5 and 1.0 mg/kg of MK-801, respectively. No difference in the degree of ataxia was seen between the two groups at 0.5 mg/kg, whereas non-lesioned animals showed a 2.1-fold higher degree of ataxia after 1.0 mg/kg of MK-801, indicating that the enhanced MK-801-induced locomotor activation in olfactory-lesioned mice was not simply due to less ataxia. These results suggest that olfactory input is involved in NMDA antagonist-induced behaviour.

Hypoxic-ischemic injury in the neonatal rat brain: effects of pre- and post-treatment with the glutamate release inhibitor BW1003C87.

In a model of perinatal hypoxia-ischemia (HI) we examined the neuroprotective efficacy of pre- and post-treatment with the glutamate release inhibitor BW1003C87 [5-(2,3,5-trichlorophenyl)-2,4-diamino-pyrimidine). Ipsilateral brain damage developed in 99% of rat pups subjected to HI (unilateral common carotid artery ligation and 100 min of 7.7% oxygen exposure) with a 26 +/- 16% (mean +/- S.D.) weight deficit of the damaged hemisphere 2 weeks after the insult. Pre-treatment with BW1003C87 (10 mg/kg intraperitoneally) reduced the brain damage by 46% (P < 0.05). A higher dose (20 mg/kg) of pre-treatment was not tolerated. Administration of BW1003C87 did not affect the rectal temperature of the rats. Post-treatment with BW1003C87 (10-30 mg/kg) offered no neuroprotection in this model. In conclusion, there was a neuroprotective effect from pre- but not post-treatment with BW1003C87 in this model, supporting the concept that intra-ischemic excitatory amino acid release is important for development of brain damage. The lack of post-treatment effect indicates that BW1003C87 did not attenuate deleterious EAA cycling during reflow in the neonatal brain.

Increased intra- and extracellular concentrations of gamma-glutamylglutamate and related dipeptides in the ischemic rat striatum: involvement of glutamyl transpeptidase.

The present work relates to the possibility that the ATP-independent enzyme gamma-glutamyl transpeptidase (EC 2.3.2.2), which has been postulated to be part of an amino acid uptake system, is active during cerebral ischemia. This was evaluated in the ischemic rat striatum by determination of intra- and extracellular concentrations of gamma-glutamyl dipeptides (the products of the transpeptidation) and glutathione (the physiological gamma-glutamyl donor). An ischemic period (0-30 and 31-60 min) resulted in prominent increases in the respective concentration of extracellular gamma-glutamylglutamate (24- and 67-fold), gamma-glutamyltaurine + gamma-glutamylglycine (5.8- and 19-fold), and gamma-glutamylglutamine (2.6- and 6.8-fold) as revealed using in vivo microdialysis. The changes coincided with increased respective extracellular concentrations of glutamate (83- and 115-fold), taurine (17- and 25-fold), glycine (4.6- and 6.1-fold), and glutamine (1.7- and 2.1-fold). Furthermore, under anoxic conditions in vitro (0-30 and 0-60 min), respective striatal tissue concentrations were increased for gamma-glutamylglutamate (20- and 17-fold), gamma-glutamyltaurine (6.7- and 11-fold), gamma-glutamylglutamine (1.7- and 1.2-fold), and gamma-glutamylglycine (14- and 18-fold), whereas glutathione levels were, on an average, decreased by approximately 350 microM. In summary, gamma-glutamyl transpeptidase is involved in de novo dipeptide synthesis in the mammalian brain during anoxic conditions, indicating transport of amino acids such as glutamate.

Neuropathological endpoints in experimental stroke pharmacotherapy: the importance of both early and late evaluation.

This study addresses the issue of endpoint selection in the evaluation of neuroprotective drugs in experimental focal ischaemia. Previous work with the permanent middle cerebral artery (MCA) occlusion model in the rat has demonstrated that the ischaemic lesion does not acquire its final appearance until at least 28 days after the ictus. Therefore, the effect of the NMDA receptor blocker MK-801 (dizocilpine maleate) was evaluated both early (3 days) and late (28 days) after MCA occlusion to determine if the previously reported protective effect of a single post-ischaemic dose of MK-801 found in acute experiments remained after 28 days. Mk-801 (0.5 mg/kg, i.v.) or isotonic saline was randomly given to rats 30 min after MCA occlusion. Infarct volume and volume of ipsilateral and contralateral hemispheres were estimated from camera lucida drawings of 8 defined coronal histological sections of the brain. As expected, a 40% (p < 0.05) reduction of infarct size was found in MK-801 treated rats after 3 days. In animals evaluated 28 days after MCA occlusion, no significant difference in infarct size, total tissue loss (infarct volume+ipsilateral hemisphere atrophy) or remaining non-infarcted tissue (contralateral hemisphere--total tissue loss) was seen between the MK-801 and placebo treated rats. The results suggest that the single dose treatment with MK-801 postponed the evolution of the infarct, which at 3 days after MCA occlusion is still in progress, possibly by ameliorating oedema formation. It remains to be shown if a multiple dose treatment with NMDA receptor antagonists improves the final neuropathological outcome after experimental stroke.(ABSTRACT TRUNCATED AT 250 WORDS)

Hypoxia-ischemia in the neonatal rat brain: histopathology after post-treatment with NMDA and non-NMDA receptor antagonists.

In a model of perinatal hypoxic-ischemic brain damage, we examined the neuroprotective efficacy of posttreatment with the NMDA receptor antagonist MK-801 and the AMPA receptor antagonist NBQX. Unilateral brain damage developed in 95% of rat pups subjected to hypoxia-ischemia with a 27.8 +/- 1.2% weight deficit of the damaged hemisphere. MK-801 in doses of 0.3 and 0.5 mg/kg i.p. reduced the brain damage by 61% (p < 0.001) and 43% (p < 0.001), respectively. A higher dose of MK-801 (0.75 mg/kg) did not offer neuroprotection. Treatment with NBQX (40 mg/kg) reduced the hemispheric lesion by 28% (p < 0.05). In conclusion, posttreatment with both NBQX and low doses of MK-801 reduced perinatal brain damage. The NMDA receptor antagonist offered stronger neuroprotection which is in agreement with a proposed NMDA receptor hyperactivity around postnatal day 7 in rats.

Changes in extracellular calcium concentration in the immature rat cerebral cortex during anoxia are not influenced by MK-801.

The extracellular calcium concentration ([Ca2+]ec) was recorded by calcium-sensitive microelectrodes in the parietal cortex of 9-11 day old rats during anoxia. During the first 10 min of anoxia, [Ca2+]ec increased from 1.1 mM to 1.5 +/- 0.23 mM, and thereafter it started to decrease reaching below basal level after around 13 min. The [Ca2+]ec decrease was either slow and continuous, or biphased with a rapid initial decrease followed by a continuous slow decrease. After 60 min of anoxia, the [Ca2+]ec had reached 0.2-0.3 mM. Changes in [Ca2+]ec in animals treated with the NMDA receptor antagonist MK-801 (0.3 mg/kg i.p.) did not display any significant differences compared to controls. Thus, the strong neuroprotective effect of MK-801 in ischemic situations in the immature brain can not be explained by a prevention of calcium entry during anoxic depolarization.

Upregulation of calpain activity in neonatal rat brain after hypoxic-ischemia.

Neonatal rats were subjected to transient cerebral hypoxic-ischemia (unilateral occlusion of the common carotid artery plus 7.7% O2 for 2 h) and allowed to recover for 0 min, 30 min or 20 h. The calpain and calpastatin activities were assayed in subcellular fractions of the ipsilateral, hypoxic-ischemic and the contralateral, hypoxic hemisphere. An upregulation of calpain activity occurred in the hypoxic hemisphere, both in the major, cytosolic fraction and in the hypotonic, membrane associated fraction (110% and 133% of controls, respectively). The hypoxic-ischemic hemisphere displayed a decrease in calpain activity in the cytosolic fraction but an increase in the hypotonic fraction (90% and 111% of controls, respectively). The changes in calpastatin activity were less pronounced. This indicates that an upregulation of calpain activity occurs in parallel with development of hypoxic-ischemic damage. However, this upregulation is not necessarily coupled to development of injury as lesions are not seen in the hypoxic hemisphere.

Involvement of adenosine in ischemic and postischemic calcium regulation.

In the CA1 region of the hippocampus, ischemia or high-frequency stimulation of the glutamatergic input induces neuronal calcium uptake that is reflected as a decrease of the extracellular concentration of calcium ([Ca2+]ec. In this study, the effects of theophylline on these [Ca2+]ec shifts were examined in doses (20 mg/kg iv) where theophylline is mainly acting by blocking adenosine receptors. By using calcium-sensitive microelectrodes, [Ca2+]ec was concomitantly recorded in stratum pyramidale (SP) and stratum radiatum (SR) of the CA1 in adult Wistar rats, before, during, and for 6 h after transient forebrain ischemia. During ischemia (4-vessel occlusion, 20 min), the [Ca2+]ec decrease in SR preceded (by 11 +/- 4 s; mean +/- SEM) the [Ca2+]ec decrease in SP. Administration of theophylline prior to ischemia reduced the time from vessel-occlusion to the ischemic decrease in [Ca2+]ec (from 3.0 +/- 0.3 to 0.9 +/- 0.1 min; mean +/- SEM; p < 0.01). During electrically evoked burst firing, the [Ca2+]ec shift was augmented by theophylline in nonischemic controls (by 29 +/- 4%; mean +/- SEM' p < 0.05). After 6 h of reflow, i.e., at a time-point when the evoked calcium uptake is enhanced, theophylline had no effect on evoked [Ca2+]ec shifts. In summary, during ischemia the uptake of calcium into CA1 pyramidal cells started in the dendrites and preceded that in the cell bodies. Removal of adenosine inhibition by theophylline accelerated ischemic calcium uptake and enhanced electrically evoked calcium uptake in control animals. In contrast, in the postischemic phase adenosine inhibition was lost with a secondary enhancement of the evoked calcium uptake that may be one critical factor in the development of delayed neuronal death.

Enhanced calcium uptake by CA1 pyramidal cell dendrites in the postischemic phase despite subnormal evoked field potentials: excitatory amino acid receptor dependency and relationship to neuronal damage.

After 6-12 h of recovery from transient cerebral ischemia, the pyramidal cells of the hippocampal CA1 region take up excessive amounts of calcium upon electrical stimulation, which has been suggested to be important for the development of delayed neuronal death. The aim of this study was to further characterize this enhanced calcium uptake with respect to time-course of development, relationship to neuronal damage, and amplitude of evoked field potentials as well as the dependency on N-methyl-D-aspartate (NMDA) and non-NMDA receptors. Adult Wistar rats were used and calcium-sensitive microelectrodes were placed in the stratum radiatum of the CA1 hippocampus for recording of the extracellular calcium concentration ([Ca2+]ec) during 20 min of ischemia and for 6 h of reflow. High-frequency stimulation of the perforant pathway elicited burst firing in CA1 and a transient decrease in [Ca2+]ec which reflects neuronal uptake. Shifts in [Ca2+]ec could not be evoked 0-1 h after ischemia. However, from 1-2 h burst firing could be evoked and the accompanying shift in [Ca2+]ec increased thereafter in amplitude with prolonged reflow, exceeded preischemic levels after 4 h, and reached 250 +/- 116% (mean +/- SD) of control after 6 h of reflow (p less than 0.05). The extracellular reference potential shift during electrical stimulation and the amplitude of evoked field potentials were still subnormal after 6 h [85 +/- 25% and 83 +/- 25%, respectively (mean +/- SD)]. There was a significant correlation between the degree of stimulated calcium uptake at 6 h postischemia and the extent of CA1 damage evaluated 7 days after the ischemic insult (r = 0.849; p less than 0.001). The shifts in [Ca2+]ec were reduced by the NMDA antagonist MK-801 (0.5-2 mg/kg, i.v.) to approximately 50% of the initial level during both control and postischemic conditions (p less than 0.01). The non-NMDA antagonist 2,3-dihydroxy-6-nitro-7-sulfamoylbenzo[F]quinoxaline (NBQX) (42 +/- 13 mg/kg, i.p.; mean +/- SD) decreased the amplitude of the evoked field potentials (to 30 +/- 28% of control, p less than 0.05) and completely abolished the evoked shifts in [Ca2+]ec. In conclusion, the uptake of calcium into CA1 pyramidal cells during electrical stimulation was enhanced already 4 h after ischemia in spite of the fact that other measures of excitability were subnormal. This calcium uptake correlated to the extent of CA1 pyramidal cell damage and was dependent on both NMDA and non-NMDA receptor activation.

Cerebral amino acids and energy metabolites in the growth retarded rat fetus under normoxia and hypoxia.

The effect of intrauterine growth retardation (IUGR) on striatal energy metabolites and amino acid concentrations was studied in the fetuses of eight nulliparous rat dams after uterine artery ligation on day 18 of gestation. On day 22 (term = 23), four dams were subjected to normoxia and four to hypoxia (10% oxygen) for 58 min, while monitoring hemodynamics and blood gases. After decapitation of the dam, fetuses were delivered by sectio and decapitated. The measured parameters in the dams were stable under normoxia but exhibited decreased oxygen availability under hypoxia. Striatal energy balance was preserved in IUGRs, both under maternal normoxic and hypoxic conditions, compared to appropriately grown (AGA) littermates. Under maternal normoxia, the striatal concentration of aspartate was reduced (P < 0.01) in IUGRs and the level of alanine was increased (P < 0.01) as compared to AGAs. Under hypoxia, the level of GABA was higher in IUGRs (P < 0.01). Lactate was increased in all fetuses under hypoxia. It is concluded that striatal energy metabolism is preserved in IUGR rat fetuses in late gestation under both maternal normoxia and hypoxia. Amino acid metabolism, however, is disturbed and depends on the degree of growth retardation and on the severity of perinatal stress.

The effect of MK-801 on cortical spreading depression in the penumbral zone following focal ischaemia in the rat.

Cortical spreading depression (CSD) is a transient depression of neuronal activity that spreads across the cortical surface. In the present studies, we have investigated CSD activity in the penumbral zone following permanent middle cerebral artery (MCA) occlusion in the rat (n = 16/group), using double-barreled Ca(2+)-sensitive microelectrodes. Measurements of CSD activity were made for 3 h in each animal. During this time, a varying number of spontaneous CSDs were seen in the control group (total was 30, with a range of 0-7/rat). These CSDs were of varying duration: "small" (approximately 1 min) and "big" (5-45 min) CSDs. During a CSD, the extracellular [Ca2+] decreased to 0.11 +/- 0.07 mM (mean +/- SD). After 3 h, the extracellular [Ca2+] in the cortex (penumbral zone) was either normal (10/16 rats) or lowered to 0.5 mM (2/16 rats) or to 0.1 mM (4/16 rats). In the caudate nucleus (ischaemic core area), all rats had an extracellular [Ca2+] of approximately 0.1 mM when measured after the 3 h recording period. Neuropathological evaluation of the brains of the animals, which had been allowed to survive for 24 h after MCA occlusion, revealed ischaemic damage in the dorsolateral cortex and caudate nucleus. Administration of the noncompetitive NMDA antagonist, MK-801 (3 mg/kg i.p.), 30 min after MCA occlusion resulted in 24 and 29% reductions in the volume of hemispheric and cortical damage, respectively, which was highly significant (p less than 0.0001); no protection was seen against caudate damage.(ABSTRACT TRUNCATED AT 250 WORDS)

Intra- and extracellular changes of amino acids in the cerebral cortex of the neonatal rat during hypoxic-ischemia.

Excitatory amino acids (EAAs) have been implicated to play a part in the development of hypoxic-ischemic brain injury in the neonate. The aim of the present study was to follow changes of intra- and extracellular (microdialysis) amino acids in the cerebral cortex in a model where cortical hypoxic-ischemic damage is produced consistently. Hypoxic-ischemia (unilateral ligation of the carotid artery + 2 h of exposure to 7.8% oxygen) caused a depletion of tissue ATP, phosphocreatine and glucose with a concomittant accumulation of AMP and lactic acid in cortical tissue. These changes were accompanied by a decrease of tissue aspartate and glutamine whereas the contents of gamma-aminobutyric acid (GABA), phenylalanine, leucine, isoleucine, valine and alanine increased. In the extracellular fluid GABA, glutamate, aspartate, taurine, glycine and alanine all increased multi-fold during hypoxic-ischemia. Aspartate and glutamate returned to near initial levels 2 h after the end of the insult, whereas the elevation of glycine persisted during recovery. In conclusion, the high extracellular levels of EAAs and glycine may exert injurious effects during and after hypoxic-ischemia.

Changes in extracellular amino acids and spontaneous neuronal activity during ischemia and extended reflow in the CA1 of the rat hippocampus.

This study addresses the possible involvement of an agonist-induced postischemic hyperactivity in the delayed neuronal death of the CA1 hippocampus in the rat. In two sets of experiments, dialytrodes were implanted into the CA1 either acutely or chronically (24 h of recovery). During 20 min of cerebral ischemia (four-vessel occlusion model) and 8 h of reflow, we followed extracellular amino acids and multiple-unit activity. Multiple-unit activity ceased within 20 sec of ischemia and remained zero during the ischemic insult and for the following 1 h of reflow. During ischemia, extracellular aspartate, glutamate, taurine, and gamma-aminobutyric acid increased in both acute and chronic experiments (seven- to 26-fold). Multiple-unit activity recovered to preischemic levels following 4-6 h of reflow. In the group with dialytrodes implanted acutely, the continuous increase in multiple-unit activity reached 110% of basal at 8 h of reflow. In the group with dialytrodes implanted chronically, multiple-unit activity recovered faster and reached 140% of control at 8 h, paralleled by an increase in extracellular aspartate (5.5-fold) and glutamate (twofold). In conclusion, the postischemic increase of excitatory amino acids and the recovery of the neuronal activity may stress the CA1 pyramidal cells, which could be detrimental in combination with, e.g., postsynaptic impairments.

Extracellular acidic sulfur-containing amino acids and gamma-glutamyl peptides in global ischemia: postischemic recovery of neuronal activity is paralleled by a tetrodotoxin-sensitive increase in cysteine sulfinate in the CA1 of the rat hippocampus.

An excessive activation of the excitatory amino acid system has been proposed as one possible mediator of the ischemia-induced delayed death of CA1 pyramidal cells in the hippocampus. Using dialytrodes in the CA1 of the rat, we have investigated multiple-unit activity and extracellular changes in acidic sulfur-containing amino acids and gamma-glutamyl peptides during ischemia (20-min, four-vessel occlusion) and during 8 h of reflow. Multiple-unit activity was abolished during ischemia and for the following 1 h, but then recovered, gradually reaching preischemic levels after 8 h of reflow. Extracellular cysteate, cysteine sulfinate, and gamma-glutamyltaurine increased (1.5- to threefold) during ischemia, and extracellular glutathione and gamma-glutamylaspartate plus gamma-glutamylglutamine increased during early reflow (two- to threefold). The recovery of neuronal activity at 4-8 h was paralleled by an increase in extracellular cysteine sulfinate (2.5-fold at 8 h of reflow). Perfusion with 10 microM tetrodotoxin at 8 h of reflow abolished the multiple-unit activity and reduced extracellular cysteine sulfinate. Considering the glutamate-like properties of cysteine sulfinate, the observed postischemic increase may be involved in the development of the delayed neuronal death.

Automated determination of neuroactive acidic sulphur-containing amino acids and gamma-glutamyl peptides using liquid chromatography with fluorescence and electrochemical detection.

A column liquid chromatographic method is presented for the determination of trace levels of acidic sulphur-containing amino acids and gamma-glutamyl di- and tripeptides in microdialysates sampled from rat brain in vivo. Automated precolumn derivatization was performed with o-phthaldialdehyde-beta-mercaptoethanol. The derivatives were separated by reversed-phase liquid chromatography with electrochemical and fluorescence detection. The mean relative standard deviation (n = 10) was 1.03 and 4.59% for retention times and peak heights, respectively. The mean correlation coefficient of linearity (r) was 0.9982 in the range 4.5-450 pmol (n = 15), and the lowest detectable amount was 200 fmol for the homocysteinesulphinic acid derivative, (k' = 5.4, at a signal-to-noise ratio of 3). A microcolumn electrochemical detection method, developed for volume-limited samples, produced a fifteen-fold increase in mass sensitivity. Neurochemical applications using microdialysis in vivo are presented.