Monoamine neurotransmitters in resected hippocampal subparcellations from neocortical and mesial temporal lobe epilepsy patients: in situ microvoltammetric studies

Mechanisms of Psychiatric Comorbidities in Epilepsy

Psychiatric illnesses, including depression and anxiety, are highly comorbid with epilepsy (for review see Josephson and Jetté (Int Rev Psychiatry 29:409-424, 2017), Salpekar and Mula (Epilepsy Behav 98:293-297, 2019)). Psychiatric comorbidities negatively impact the quality of life of patients (Johnson et al., Epilepsia 45:544-550, 2004; Cramer et al., Epilepsy Behav 4:515-521, 2003) and present a significant challenge to treating patients with epilepsy (Hitiris et al., Epilepsy Res 75:192-196, 2007; Petrovski et al., Neurology 75:1015-1021, 2010; Fazel et al., Lancet 382:1646-1654, 2013) (for review see Kanner (Seizure 49:79-82, 2017)). It has long been acknowledged that there is an association between psychiatric illnesses and epilepsy. Hippocrates, in the fourth-fifth century B.C., considered epilepsy and melancholia to be closely related in which he writes that "melancholics ordinarily become epileptics, and epileptics, melancholics" (Lewis, J Ment Sci 80:1-42, 1934). The Babylonians also recognized the frequency of psychosis in patients with epilepsy (Reynolds and Kinnier Wilson, Epilepsia 49:1488-1490, 2008). Despite the fact that the relationship between psychiatric comorbidities and epilepsy has been recognized for thousands of years, psychiatric illnesses in people with epilepsy still commonly go undiagnosed and untreated (Hermann et al., Epilepsia 41(Suppl 2):S31-S41, 2000) and systematic research in this area is still lacking (Devinsky, Epilepsy Behav 4(Suppl 4):S2-S10, 2003). Thus, although it is clear that these are not new issues, there is a need for improvements in the screening and management of patients with psychiatric comorbidities in epilepsy (Lopez et al., Epilepsy Behav 98:302-305, 2019) and progress is needed to understand the underlying neurobiology contributing to these comorbid conditions. To that end, this chapter will raise awareness regarding the scope of the problem as it relates to comorbid psychiatric illnesses and epilepsy and review our current understanding of the potential mechanisms contributing to these comorbidities, focusing on both basic science and clinical research findings.

Neuromolecular imaging, a nanobiotechnology for Parkinson's disease: advancing pharmacotherapy for personalized medicine

Evaluating each patient and animal as its own control achieves personalized medicine, which honors the hippocratic philosophy, explaining that "it is far more important to know what person has the disease than what disease the person has." Similarly, individualizing molecular signaling directly from the patient's brain in real time is essential for providing prompt, patient-based treatment as dictated by the point of care. Fortunately, nanotechnology effectively treats many neurodegenerative diseases. In particular, the new medicinal frontier for the discovery of therapy for Parkinson's disease is nanotechnology and nanobiotechnology. Indeed, the unique nanotechnology of neuromolecular imaging combined with the series of nanobiosensors enables continuous videotracking of molecular neurotransmitters in both the normal physiologic and disease states with long-term electrochemical operational stability. This nanobiotechnology is able to track a signal in real time with excellent temporal and spatial resolution directly from each patient's brain to a computer as subjects are behaving during movement, normal and/or dysfunctional including prion-like Parkinson's behavioral biometrics. Moreover, the molecular signaling performed by these nanobiosensors live streams directly online and originates from precise neuroanatomic brain sites such as, in this case, the dorsal striatum in basal ganglia. Thus, the nanobiotechnology studies discussed herein imaged neuromolecules with and without L-3,4-dihydroxyphenylalanine (L-DOPA) in dorsal striatal basal ganglia neurons. Parkinsonian and non-Parkinsonian animals were video-tracked, and images were readily seen on a laptop via a potentiostat using a semiderivative electrical circuit. Administered L-DOPA doses were 50 and 100 mg/kg intraperitoneally (ip); the same experimental paradigm was used to image and then contrast data. Results showed that the baseline release of biogenic amine molecules was significantly above detection limits in non-Parkinsonian animals. After administration of L-DOPA, biogenic amines significantly increased in these non-Parkinson's animals. Nevertheless, it is intriguing to see that L-DOPA could not enable synaptic dopamine release in Parkinson's animals, thereby demonstrating that biogenic amines are biomarkers for Parkinson's disease. Biomarkers are biochemical, genetic, or molecular measures of biological reactions. Importantly, there were other significant biomarkers present in Parkinsonian animals and absent in non-Parkinsonian animals; these were peptide neurotransmitters that include dynorphin and somatostatin in the brain with detection limits of 40 nM for dynorphin and 37 nM for somatostatin (see Table 1). Furthermore, L-DOPA significantly increased these peptide biomarkers, dynorphin and somatostatin, in Parkinson's animals. Targeting biomarkers enables new diagnostic devices and treatments for Parkinson's disease through nanotechnology and nanobiotechnology.

The effects of electrical hippocampal kindling of seizures on amino acids and kynurenic acid concentrations in brain structures

Our study demonstrated that the development of seizures during the electrically induced kindling of seizures is associated with significant changes in the concentration of kynurenic acid (KYNA) and its precursor, tryptophan (TRP). The primary finding of our study was an increase in KYNA levels and the KYNA/TRP ratio (a theoretical index of activity of the kynurenine pathway) in the amygdala and hippocampus of kindled animals. We also found decreases in the concentration of tryptophan in the hippocampus and prefrontal cortex. Changes in the concentration of KYNA and TRP in the amygdala were accompanied by a significant decrease in γ-Aminobutryic Acid (GABA) levels and an increase in the glutamate/GABA ratio. Moreover, we found a significant negative correlation between the local concentrations of KYNA and glutamate in the amygdala of kindled rats. However, there were no changes in the local concentrations of the following amino acids: glutamate, aspartate, glutamine, glycine, taurine and alanine. In conclusion, these new results suggest a modulatory influence of KYNA on the process of epileptogenesis, characterized by a negative relationship between the KYNA and glutamate systems in the amygdala.

Biosensors for brain trauma and dual laser doppler flowmetry: enoxaparin simultaneously reduces stroke-induced dopamine and blood flow while enhancing serotonin and blood flow in motor neurons of brain, in vivo

Neuromolecular Imaging (NMI) based on adsorptive electrochemistry, combined with Dual Laser Doppler Flowmetry (LDF) is presented herein to investigate the brain neurochemistry affected by enoxaparin (Lovenox(®)), an antiplatelet/antithrombotic medication for stroke victims. NMI with miniature biosensors enables neurotransmitter and neuropeptide (NT) imaging; each NT is imaged with a response time in milliseconds. A semiderivative electronic reduction circuit images several NT's selectively and separately within a response time of minutes. Spatial resolution of NMI biosensors is in the range of nanomicrons and electrochemically-induced current ranges are in pico- and nano-amperes. Simultaneously with NMI, the LDF technology presented herein operates on line by illuminating the living brain, in this example, in dorso-striatal neuroanatomic substrates via a laser sensor with low power laser light containing optical fiber light guides. NMI biotechnology with BRODERICK PROBE(®) biosensors has a distinct advantage over conventional electrochemical methodologies both in novelty of biosensor formulations and on-line imaging capabilities in the biosensor field. NMI with unique biocompatible biosensors precisely images NT in the body, blood and brain of animals and humans using characteristic experimentally derived half-wave potentials driven by oxidative electron transfer. Enoxaparin is a first line clinical treatment prescribed to halt the progression of acute ischemic stroke (AIS). In the present studies, BRODERICK PROBE(®) laurate biosensors and LDF laser sensors are placed in dorsal striatum (DStr) dopaminergic motor neurons in basal ganglia of brain in living animals; basal ganglia influence movement disorders such as those correlated with AIS. The purpose of these studies is to understand what is happening in brain neurochemistry and cerebral blood perfusion after causal AIS by middle cerebral artery occlusion in vivo as well as to understand consequent enoxaparin and reperfusion effects actually while enoxaparin is inhibiting blood clots to alleviate AIS symptomatology. This research is directly correlated with the medical and clinical needs of stroke victims. The data are clinically relevant, not only to movement dysfunction but also to the depressive mood that stroke patients often endure. These are the first studies to image brain neurotransmitters while any stroke medications, such as anti-platelet/anti-thrombotic and/or anti-glycoprotein are working in organ systems to alleviate the debilitating consequences of brain trauma and stroke/brain attacks.

Real Time Imaging of Biomarkers in the Parkinson's Brain Using Mini-Implantable Biosensors. II. Pharmaceutical Therapy with Bromocriptine

We used Neuromolecular Imaging (NMI) and trademarked BRODERICK PROBE^® mini-implantable biosensors, to selectively and separately detect neurotransmitters in vivo, on line, within seconds in the dorsal striatal brain of the Parkinson's Disease (PD) animal model. We directly compared our results derived from PD to the normal striatal brain of the non-Parkinson's Disease (non-PD) animal. This advanced biotechnology enabled the imaging of dopamine (DA), serotonin (5-HT), homovanillic acid (HVA) a metabolite of DA, L-tryptophan (L-TP) a precursor to 5-HT and peptides, dynorphin A 1-17 (Dyn A) and somatostatin (somatostatin releasing inhibitory factor) (SRIF). Each neurotransmitter and neurochemical was imaged at a signature electroactive oxidation/half-wave potential in dorsal striatum of the PD as compared with the non-PD animal. Both endogenous and bromocriptine-treated neurochemical profiles in PD and non-PD were imaged using the same experimental paradigm and detection sensitivities. Results showed that we have found significant neurotransmitter peptide biomarkers in the dorsal striatal brain of endogenous and bromocriptine-treated PD animals. The peptide biomarkers were not imaged in dorsal striatal brain of non-PD animals, either endogenously or bromocriptine-treated. These findings provide new pharmacotherapeutic strategies for PD patients. Thus, our findings are highly applicable to the clinical treatment of PD.

Mesial temporal sclerosis associated with methotrexate-induced leukoencephalopathy

Mesial temporal sclerosis is a common form of symptomatic, localization-related epilepsy in children and adolescents, but its occurrence with acute lymphoblastic leukemia is rare. We present clinical records and neuroimaging results of a 13-year-old patient with acute lymphoblastic leukemia who developed recurrent partial seizures after an episode of leukoencephalopathy thought to be caused by methotrexate. Neuroradiologic images revealed hippocampal abnormalities consistent with the findings of mesial temporal sclerosis. Mesial temporal sclerosis was not previously reported in acute lymphoblastic leukemia patients with methotrexate-induced leukoencephalopathy. However, our case suggests that the pathogenesis of mesial temporal sclerosis may be associated with methotrexate-induced neurotoxicity.

Depression after status epilepticus: behavioural and biochemical deficits and effects of fluoxetine

Depression represents one of the most common comorbidities in patients with epilepsy. However, the mechanisms of depression in epilepsy patients are poorly understood. Establishment of animal models of this comorbidity is critical for both understanding the mechanisms of the condition, and for preclinical development of effective therapies. The current study examined whether a commonly used animal model of temporal lobe epilepsy (TLE) is characterized by behavioural and biochemical alterations involved in depression. Male Wistar rats were subjected to LiCl and pilocarpine status epilepticus (SE). The development of chronic epileptic state was confirmed by the presence of spontaneous seizures and by enhanced brain excitability. Post-SE animals exhibited increase in immobility time under conditions of forced swim test (FST) which was indicative of despair-like state, and loss of taste preference in saccharin solution consumption test which pointed to the symptomatic equivalence of anhedonia. Biochemical studies revealed compromised serotonergic transmission in the raphe-hippocampal serotonergic pathway: decrease of serotonin (5-HT) concentration and turnover in the hippocampus, measured by high performance liquid chromatography, and decrease of 5-HT release from the hippocampus in response to raphe stimulation, measured by fast cyclic voltammetry. Administration of fluoxetine (FLX, 20 mg/kg/day for 10 days) to naive animals significantly shortened immobility time under conditions of FST, and inhibited 5-HT turnover in the hippocampus. In post-SE rats FLX treatment led to a further decrease of hippocampal 5-HT turnover; however, performance in FST was not improved. At the same time, FLX reversed SE-induced increase in brain excitability. In summary, our studies provide initial evidence that post-SE model of TLE might serve as a model of the comorbidity of epilepsy and depression. The finding that behavioural equivalents of depression were resistant to an antidepressant medication suggested that depression in epilepsy might have distinct underlying mechanisms beyond alterations in serotonergic pathways.

Studies of oxidative stress mechanisms using a morphine / ascorbate animal model and novel N-stearoyl cerebroside and laurate sensors

The field of oxidative stress, free radicals, cellular defense and antioxidants is a burgeoning field of research. An important biomarker of oxidative stress is ascorbate and alterations in ascorbate have been shown to be a reliable measure of oxidative stress mechanisms. The purpose of this pharmacological study was to assess changes in ascorbate in a morphine/ascorbate animal model using novel sensors which selectively detect electrochemical signals for ascorbate, dopamine (DA) and serotonin (5-HT). Studies were also performed to show reversal of morphine-induced effects by the opioid antagonist, naloxone. In vivo studies were modeled after (Enrico et al. 1997, 1998) in which the oxidative biomarker, ascorbate, was reported to compensate for free radicals produced by morphine-induced increases in DA and 5-HT. In vivo studies consisted of inserting the Laurate sensor in ventrolateral nucleus accumbens (vlNAcc), in anesthetized male, Sprague-Dawley rats. In separate studies, laboratory rats were injected with (1) ascorbate, (5-35 mg/kg, ip) or (2) dehydroascorbate (DHA) (20-100 mg/kg, ip). In another study, (3) morphine sulfate (10-20 mg/kg, sc) was injected followed by a single injection of naloxone (5 mg/kg, ip) in the same animal. Results showed that in vlNAcc, (1) neither ascorbate nor DHA injections produced ascorbate release, (2) morphine significantly increased DA and 5-HT release, but did not alter ascorbate release, and (3) naloxone significantly reversed the increased DA and 5-HT release produced by morphine. Moreover, the sensors, N-stearoyl cerebroside and laurate were studied in vitro, in separate studies, in order to assess selective and separate electrochemical detection of ascorbate, DA and 5-HT, neuromolecules involved in oxidative stress mechanisms. In vitro studies consisted of pretreatment of each sensor with a solution of phosphotidylethanolamine (PEA) and bovine serum albumin (BSA) which simulates the lipid/protein composition of brain. Each new sensor was tested for stability, sensitivity and selectivity by pipetting graduated increases in concentration of ascorbate, DA and 5-HT into an electrochemical cell containing saline/phosphate buffer. Multiple and repetitive images of electrochemical signals from ascorbate, DA and 5-HT were recorded. Results showed that both sensors produced three well-defined cathodic, selective and separate electrochemical signals for ascorbate, DA and 5-HT at characteristic oxidation potentials. Dopamine and 5-HT were detected at nM concentrations while ascorbate was detected at microM concentrations. In summary, the data show that very low concentrations of ascorbate occurred in vlNAcc since novel sensors detected ascorbate at high concentrations in vitro. The data indicate that little or no change in oxidative stress mechanisms occurred in vlNAcc after morphine or naloxone administration since the oxidative biomarker, ascorbate, was not signifi cantly altered. Thus, oxidative stress mechanisms and novel N-stearoyl cerebroside and laurate sensors, which selectively detect and separate neuromolecules involved in these mechanisms, may be potentially clinically relevant.

Monoamine and motor responses to cocaine are co-deficient in the Fawn-Hooded depressed animal model

The Fawn-Hooded (FH) genetic animal model of depression continues to be of interest because the FH model has limited biochemical and immune function. The FH animal has an inherited trait, platelet storage pool deficiency (PSPD), an hemorrhagic disorder that is also a component of Chediak-Higashi syndrome (CHS). CHS is a pyrogenic infectious childhood disease; few patients live past the age of 20. Our hypothesis was that FH animals may exhibit different monoamine and motor responses to cocaine versus the Sprague-Dawley (SD) "normal" animal strain, which does not have the FH trait. Therefore, selective neuromolecular imaging (NMI) of the monoamines, dopamine (DA) and 5-HT within nucleus accumbens (NAcc) of behaving male FH versus SD rats was performed in vivo with BRODERICK PROBE sensors and a semiderivative voltammetric circuit. Each animal was placed in a faraday chamber and electrochemical signals were detected via a mercury commutator and flexible cable. Baseline values for neurotransmitters and behavior were derived during the last half-hour of habituation behavior. Release of DA and 5-HT was detected selectively, at separate oxidation potentials, within seconds, before and after intraperitoneal administration of the psychostimulant, cocaine (10 mg/kg). At the same time, frequencies of ambulations and central ambulations were separately monitored with infrared photobeams, which surrounded the faraday chamber. Data were compared by ANOVA analysis followed by Tukey's post hoc test. The data showed that (1) DA release in NAcc of behaving FH animals did not respond to cocaine; neither first hour nor second hour values significantly differed from baseline (both hours, p>0.05), whereas SD animals exhibited a significant increase in cocaine-induced DA release in NAcc (both hours, p<0.001). The ability for acute cocaine to increase DA release in NAcc was significantly greater in SD than in FH animals (p<0.001). (2) 5-HT release in NAcc of behaving FH animals was not significantly increased by cocaine (both hours, p>0.05), whereas 5-HT release in NAcc of SD animals was significantly increased after cocaine (both hours, p<0.001). The ability for acute cocaine to increase 5-HT release was significantly greater in SD than in FH animals (p<0.001). (3) Ambulations in the FH strain were modestly, yet significantly, enhanced after cocaine during both hours of study (p<0.05, p<0.001, respectively) as were ambulations in the SD strain. Nonetheless, the ability for acute cocaine to increase ambulations was significantly greater in SD than in FH animals in the first hour (p<0.001). (4) Central ambulations in the FH strain was not affected by cocaine (both hours, p>0.05), whereas SD animals showed a significant increase in central ambulatory activity in both hours of the cocaine study (p<0.001). The ability for acute cocaine to increase central ambulations was significantly greater in SD than in FH animals (p<0.001). Thus, this is the first study to determine in vivo the neurochemical response to acute cocaine in the behaving FH animal. Moreover, this is the first study to determine in vivo and simultaneously the neurochemical and behavioral response to acute cocaine in the FH strain in comparison with SD animals, a "normal" strain. Remarkable deficiencies in the ability for acute cocaine to alter neurochemistry and behavior in animals with the FH trait are shown. These studies emphasize the need to look differentially at cocaine effects in biochemically and immune-compromised subjects versus "normal" subjects.

Electroanalytical method for determination of the pesticide dichlorvos using gold-disk microelectrodes

This paper reports the use of laboratory-prepared gold microelectrodes and square-wave voltammetry for analytical determination of low concentrations of the pesticide dichlorvos in pure and natural water samples. After optimization of the experimental and voltammetric conditions, the best voltammetric responses-current intensity and voltammetric profile-were obtained in 0.1 mol L(-1) NaClO4 with f=100 s(-1), a=50 mV, and DeltaE(s)=2 mV. The observed detection and quantification limits in pure water were 7.8 and 26.0 microg L(-1), respectively. The reproducibility and repeatability of the method were also determined; the results were 1.4% (n=5) and 1.2% (n=10), respectively. Possible interfering effects were evaluated in natural water samples collected at different points with different levels of contamination from agricultural, domestic, or industrial waste from an urban stream. Results showed that the detection and quantification limits increased as a function of the quantity of organic matter present in the samples. Nonetheless, the values observed for these method characteristics were below the maximum value allowed by the Brazilian code for organophosphorus pesticides in water samples. Recovery curves constructed using the standard addition method were shown to be satisfactory compared with those obtained from high-performance liquid chromatography, confirming the suitability of the method for analysis of natural water samples. Finally, when the method was used to determine dichlorvos in spiked cows' milk samples, satisfactory recovery and relative standard deviations were obtained.

Cocaine acts on accumbens monoamines and locomotor behavior via a 5-HT2A/2C receptor mechanism as shown by ketanserin: 24-h follow-up studies

It is well known that cocaine's psychomotor stimulant properties derive from enhanced monoamines via synaptic transporter/reuptake inhibition and release mechanisms. However, to further understand mechanisms of action for cocaine, which may be receptor-related, ketanserin, a selective 5-HT(2A/2C) antagonist was used to ascertain a possible mediation for 5-HT(2A//2C) receptors in the monoamine and behavioral responses to cocaine. The studies were performed in the freely moving and behaving animal with In Vivo Microvoltammetry. Miniature carbon sensors, BRODERICK PROBE microelectrodes detected dopamine (DA) and serotonin (5-HT) concentrations in Nucleus Accumbens (NAcc) of male, Sprague-Dawley laboratory rats in separate signals and within seconds while at the same time, locomotor behavior was monitored with infrared photobeams. Synaptic release of each monoamine was detected because separate studies showed that the depolarization blocker, gamma-butyrolactone (gamma BL), decreased steady-state values [Pharmacol. Biochem. Behav. 40 (1991) 969]. Acute studies (Day 1) were performed; the animals received single injection of drug(s) in the faradaic behavioral chamber after a stable baseline during habituation behavior was achieved. After completion of the study, the animals were returned to their home cages. Subacute studies (Day 2) were also performed; these took place 24 h later in the faradaic behavioral chamber; same animal control was used and no further drug was administered. Day 2 data were compared to baseline (habituation data) on Day 1. Results showed that (1) Acute administration of Cocaine (10 mg/kg, i.p.) (N=5) increased DA and 5-HT release above baseline (p<0.001) while locomotion was also increased above baseline (p<0.001). (2) In Subacute studies in the cocaine group, when no further drug was administered, DA release decreased (p<0.001) and decreases in 5-HT release also occurred throughout the time course (p<0.05). Locomotor behavior increased above baseline and showed a trend toward statistical significance (p<0.07). (3) Acute administration of Ketanserin/Cocaine (3 mg/kg s.c. and 10 mg/kg i.p., respectively) (N=6) showed that ketanserin antagonized DA and 5-HT release (p<0.001), while locomotion was antagonized as well (p<0.001). (4) In Subacute studies, in the ketanserin/cocaine group, when no further drug was administered, DA decreased (p<0.001), but 5-HT increased (p<0.001), while locomotor activity increased above baseline and a trend toward statistical significance was seen (p<0.07). Additional saline controls were without effect (p>0.05). In summary, Acute studies showed that cocaine produced its psychostimulant responses on monoamines and behavior and ketanserin antagonized these responses, likely via a 5-HT(2A/2C) receptor mediation. Presynaptic and postsynaptic responses were not distinguished, suggesting, in addition, a role for 5-HT-ergic modulation of DA, likely DA(2) postsynaptic modulation Subacute cocaine studies showed that on Day 2, deficiencies in monoamines occurred, reflecting cocaine withdrawal mechanisms neurochemically, while locomotor behavior did not show such dramatic deficiencies. Indeed, behavior increased above baseline. Moreover, ketanserin reversed 5-HT-related and not DA-related cocaine monoamine responses, while locomotion continued to be insignificantly increased above baseline as was seen in the Subacute cocaine group. The data suggest that presynaptic 5-HT(2A/2C) receptor mechanisms may be important during withdrawal from single injection of cocaine.

Clozapine and cocaine effects on dopamine and serotonin release in nucleus accumbens during psychostimulant behavior and withdrawal

There is an increasing awareness that a psychosis, similar to that of schizophrenic psychosis, can be derived from cocaine addiction. Thus, the prototypical atypical antipsychotic medication, clozapine, a 5-HT(2)/DA(2) antagonist, was studied for its effects on cocaine-induced dopamine (DA) and serotonin (5-HT) release in nucleus accumbens (NAcc) of behaving male Sprague-Dawley laboratory rats with In Vivo Microvoltammetry, while animals' locomotor (forward ambulations), an A(10) behavior, was monitored at the same time with infrared photobeams. Release mechanisms for monoamines were determined by using a depolarization blocker, gamma-butyrolactone (gammaBL). BRODERICK PROBE microelectrodes selectively detected release of DA and 5-HT within seconds and sequentially in A(10) nerve terminals, NAcc. Acute and subacute studies were performed for each treatment group. Acute studies are defined as single injection of drug(s) after a stable baseline of each monoamine and locomotor behavior has been achieved. Subacute studies are defined as 24-h follow-up studies on each monoamine and locomotor behavior, in the same animal at which time, no further drug was administered. Results showed that (1) acute administration of cocaine (10 mg/kg ip) (n=5) significantly increased both DA and 5-HT release above baseline (P<.001) while locomotion was also significantly increased above baseline (P<.001). In subacute studies, DA release decreased significantly below baseline (P<.001) and significant decreases in 5-HT release occurred at the 15-min mark and at each time point during the second part of the hour (P<.05); the maximum decrease in 5-HT was 40% below baseline. Locomotor behavior, on the other hand, increased significantly above baseline (P<.05). (2) Acute administration of clozapine/cocaine (20 and 10 mg/kg ip, respectively; n=6) produced a significant block of the cocaine-induced increase in DA (P<.001) and 5-HT release (P<.001). Cocaine-induced locomotion was blocked simultaneously with each monoamine by clozapine as well (P<.001). In subacute studies, DA release continued to be blocked presumably via clozapine by exhibiting a statistically significant decrease (P<.001), but 5-HT release increased significantly (P<.001), while cocaine-induced locomotor activity also continued to be antagonized by clozapine, i.e., locomotor activity exhibited no difference from baseline (P>.05). In summary, acute studies (a) support previous data from this laboratory and others that cocaine acts as a stimulant on the monoamines, DA and 5-HT and on locomotor behavior as well and (b) show that clozapine, 5-HT(2)/DA(2) antagonist, blocked enhanced DA, 5-HT and psychomotor stimulant behavior induced by cocaine. Subacute studies (a) suggest that withdrawal responses occurred in the cocaine group, based on recorded deficiencies in monoamine neurotransmitters (b) show that withdrawal effects in the cocaine group likely presynaptic, were distinguished from locomotor behavior, classically known to be mediated postsynaptically, and finally, (c) suggest that clozapine, with longer lived pharmacokinetic properties, reversed 5-HT cocaine-related withdrawal effects, but was unable to reverse DA cocaine-related withdrawal responses. Taken together with data from this laboratory, in which the 5-HT(2A/2C) antagonist, ketanserin, affected cocaine neurochemistry in much the same way as did clozapine, a mediation by either separate or combined 5-HT(2A/2C) receptors for these clozapine/cocaine interactions, is suggested. Further studies, designed to tease out the responses of selective 5-HT(2A) and 5-HT(2C) receptor compounds to cocaine and clozapine/cocaine, are underway.

Acute and subacute effects of risperidone and cocaine on accumbens dopamine and serotonin release using in vivo microvoltammetry on line with open-field behavior

In vivo microvoltammetry was used to detect dopamine (DA) and serotonin (5-HT) release from nucleus accumbens (NAcc) of freely moving, male, Sprague-Dawley laboratory rats, while animals' locomotor (forward ambulations) and stereotypic behavior (fine movements of sniffing and grooming) were monitored at the same time with infrared photobeams. Monoamine release mechanisms were determined by using a depolarization blocker (gamma-butyrolactone, gamma BL). Miniature carbon sensors (BRODERICK PROBES microelectrodes) smaller than a human hair were used in conjunction with a semidifferential electrochemical circuit to detect release of each monoamine in separate signals and within seconds. The purpose was to evaluate the neuropharmacology of the 5-HT(2)/DA(2) antagonist risperidone in its current therapeutic role as an atypical antipsychotic medication as well as in its potential role as pharmacotherapy for cocaine psychosis and withdrawal symptoms. Acute (single drug dose) and subacute (24-h follow-up studies in the same animal, no drug administration) studies were performed for each treatment group. The hypothesis for the present studies is derived from a growing body of evidence that cocaine-induced psychosis and schizophrenic psychosis share similar neurochemical and behavioral manifestations. Results showed that (1) Acute administration of risperidone (2 mg/kg sc) significantly increased DA and 5-HT release in NAcc above baseline (habituation) values (P<.001) while locomotion and stereotypy were virtually unaffected. In subacute studies, DA release did not differ from baseline (P>.05), whereas 5-HT release was significantly increased above baseline (P<.001). Locomotion increased over baseline but not to a significant degree, while stereotypy was significantly increased above baseline (P<.05). (2) Acute administration of cocaine (10 mg/kg ip) significantly increased both DA and 5-HT release above baseline (P<.001), while locomotion and stereotypy were significantly increased over baseline (P<.001). In subacute studies, DA decreased significantly below baseline (P<.001) and significant decreases in 5-HT release occurred at 15, 20, 50 and 55 min (P<.05). Behavior increased above baseline but did not reach a statistically significant degree. (3) Acute administration of risperidone/cocaine (2 mg/kg sc and 10 mg/kg ip, respectively) showed a significant block of the cocaine-induced increase in DA release in the first hour (P<.001) and 5-HT release in both hours of study (P<.001). Cocaine-induced locomotion and stereotypy were blocked simultaneously with the monoamines (P<.001). In subacute studies, DA and 5-HT release returned to baseline while locomotion and stereotypy increased insignificantly above baseline. Thus, (a) these studies were able to tease out pharmacologically the critical differences between presynaptic and postsynaptic responses to drug treatment(s) and these differences may lead to more effective therapies for schizophrenic and/or cocaine psychosis. (b) Taken together with other data, these acute studies suggest that risperidone may possibly act via inhibition of presynaptic autoreceptors to produce the observed increases in accumbens DA and 5-HT release, whereas cocaine may be acting at least in part via serotoninergic modulation of DA postsynaptically. The subacute data suggest that pharmacokinetics may play a role in risperidone's action and that neuroadaptation may play a role in the mechanism of action of cocaine. Finally, the ability of risperidone to block cocaine-induced psychostimulant neurochemistry and behavior during acute studies while diminishing the withdrawal symptoms of cocaine during subacute studies suggests that risperidone may be a viable pharmacotherapy for cocaine psychosis and withdrawal.

Interleukin 1alpha alters hippocampal serotonin and norepinephrine release during open-field behavior in Sprague-Dawley animals: differences from the Fawn-Hooded animal model of depression

Detection of two biogenic amine neurotransmitters, serotonin (5-HT) and norepinephrine (NE) within the CA1 region of the hippocampus (HPC) of behaving male laboratory animals (Rattus norvegicus), was performed with miniature carbon sensors (BRODERICK PROBES) and in vivo semidifferential microvoltammetry after acute administration of the soluble immune factor, human recombinant, interleukin (IL) 1alpha (10 and 100 ng/kg i.p.). Two animal models were compared, i.e., (a) the Sprague-Dawley (SD) model, a strain neither biochemically nor immune-challenged and (b) the Fawn-Hooded (FH) model, a biochemically (5-HT-deficient) and immune-challenged animal. Open-field behaviors, locomotion (ambulations) and stereotypy (fine movements of sniffing and grooming) were monitored with infrared photobeams while 5-HT and NE were selectively and separately detected within seconds in real time. Subchronic studies were performed in the same animals 24 h later at which time no further drug was administered. Results from acute treatment studies showed that IL-1alpha altered HPC monoamines and behavior viz-a-viz habituation values (baseline) in the SD strain differently from those in the FH strain as follows: (1) although 5-HT release was significantly increased within CA1 region of HPC in both SD and FH strains (P<.0001), the extent of the HPC 5-HT increase in the 5-HT-deficient FH strain was significantly less than that of the SD strain at both doses (P<.0001). The subchronic studies showed that 5-HT release within the HPC in the SD strain significantly increased (135%) over drug treatment values (P<.001), whereas HPC 5-HT release in the FH strain remained the same as that seen in the acute drug treatment studies; the difference between strains for the subchronic study was also statistically significant (P<.01). (2) IL-1alpha significantly decreased HPC NE release in the SD strain (P<.0004) while IL-1alpha decreased HPC NE release in the FH strain only at the 10-ng/kg dose (P<.001); at the 100-ng/kg dose in the FH strain, NE rebounded towards baseline and increased 15% above baseline reaching statistical significance (P<.05). Subchronic studies in the SD strain showed a further decreased NE signal to 38% below baseline (P<.0001), whereas subchronic studies in the FH strain showed a significant increase in NE release (P<.02). The difference between strains in the subchronic NE studies was significant (P<.001). (3) Ambulations were increased after IL-1alpha administration in acute studies in both the SD and the FH strains, but the increase did not reach statistical significance, whereas in the subchronic studies, both strains exhibited significant increases as revealed by post hoc analyses (P<.05). There was a statistically significant difference between strains in acute studies (P<.001), whereas no significant differences between models were seen in ambulation behavior in subchronic studies. (4) Fine movements increased over baseline after IL-1alpha administration in both animal models in acute studies, however, results did not reach statistical significance, likely due to the episodic effect of IL-1alpha on movement behavior in both the SD and the FH strains. However, the SD strain showed a significant increase in fine movement behavior during the subchronic studies (P<.02). Significant differences in fine movements between animal models were not observed either acutely or in subchronic studies. In summary, the data show that immune modulation by IL-1alpha affects HPC neurochemistry and behavior in SD versus FH animal models differently and/or to different degrees. The data show that while the FH animal model is subsensitive to 5-HT agonists, 5-HT function can be stimulated. Comparison of genetically diverse animal models provides a reliable means to identify and discern cytokine-induced depressive versus stressor properties. Selective sensor technology provides a powerful tool as movement behavior is monitored and interpreted as a function of monoamine neurotransmission.

Biogenic amines in the human neocortex in patients with neocortical and mesial temporal lobe epilepsy: identification with in situ microvoltammetry

Biogenic amines in well defined subtypes of human temporal lobe epilepsy (TLE) have not been well characterized. Specimens from five patients with neocortical TLE (NTLE) and nine with mesial TLE (MTLE) were immediately placed in Ringer's lactate; stearate indicator microelectrodes were placed in temporal gray matter, Ag/AgCl reference microelectrodes and auxiliary microelectrodes were placed 3-7 mm contralaterally to the indicator microelectrode. Dopamine (DA), ascorbic acid (AA), norepinephrine (NE) and serotonin (5-HT) were identified by their characteristic oxidative potentials in vitro. Four of five patients with NTLE had NE depletion in temporal neocortex while eight of nine patients with MTLE had high concentrations of NE (chi-square P<0.01). Significant concentrations of DA were present in the temporal lobes of three of five NTLE patients but in only one of the nine MTLE patients (chi-square P<0.05). 5-HT was present in the neocortex of both NTLE and MTLE patients in similar concentrations. AA was found in the neocortex of one NTLE patient. These data support an association between NE depletion and NTLE. The relative NE deficiency along with the consistent presence of DA in NTLE patients suggest an impairment in the catecholamine pathway. The presence of AA, a co-factor in NE synthesis, in the neocortex of one NTLE patient may also be related since AA is a cofactor in NE synthesis.