Antipruritic effects of geraniol on acute and chronic itch via modulating spinal GABA/GRPR signaling.

BACKGROUND AND PURPOSE: Itch (pruritus) is a common unpleasant feeling, often accompanied by the urge of scratching the skin. It is the main symptom of many systemic and skin diseases, which can seriously affect the patient's quality of life. Geraniol (GE; trans-3,7-dimethyl-2,6-octadien-1-ol) is a natural monoterpene with diverse effects, including anti-inflammatory, antioxidant, neuroprotective, anti-nociceptive, and anticancer properties. The study aims to examine the effects of GE on acute and chronic itch, and explore the underlying mechanisms. METHODS: Acute itch was investigated by using Chloroquine and compound 48/80 induced model, followed by manifestation of diphenylcyclopropenone (DCP)-induced allergic contact dermatitis and the acetone-ether-water (AEW)-induced dry skin model in mice. The scratching behavior, skin thickness, c-Fos expression, and GRPR protein expression in the spinal cord were subsequently monitored and evaluated by behavioral tests as well as pharmacological and pharmacogenetic technologies. RESULTS: Dose-dependent intraperitoneal injection of GE alleviated the acute itch, induced by chloroquine and compound 48/80, as well as increased the spinal c-Fos expression. Intrathecal administration of GE suppressed the GABAA receptor inhibitor bicuculline-induced itch, GRP-induced itch, and the GABAergic neuron inhibition-induced itch. Furthermore, the subeffective dose of bicuculline blocked the anti-pruritic effect of GE on the chloroquine and compound 48/80 induced acute itch. GE also attenuated DCP and AEW-induced chronic itch, as well as the increase of spinal GRPR expression in DCP mice. CONCLUSION AND IMPLICATIONS: GE alleviates both acute and chronic itch via modulating the spinal GABA/GRPR signaling in mice. Findings of this study reveal that GE may provide promising therapeutic options for itch management. Also, considering the pivotal role of essential oils in aromatherapy, GE has great application potential in aromatherapy for treating skin diseases, and especially the skin with severe pruritus.

Noradrenaline and Seizures: A Perspective on the Role of Adrenergic Receptors in Limbic Seizures.

BACKGROUND: Noradrenergic fibers originating from the locus coeruleus densely innervate limbic structures, including the piriform cortex, which is the limbic structure with the lowest seizure threshold. Noradrenaline (NA) modulates limbic seizures while stimulating autophagy through ß2- adrenergic receptors (AR). Since autophagy is related to seizure threshold, this perspective questions whether modulating ß2-AR focally within the anterior piriform cortex affects limbic seizures. OBJECTIVE: In this perspective, we analyzed a potential role for ß2-AR as an anticonvulsant target within the anterior piriform cortex, area tempestas (AT). METHODS: We developed this perspective based on current literature on the role of NA in limbic seizures and autophagy. The perspective is also grounded on preliminary data obtained by microinfusing within AT either a ß2-AR agonist (salbutamol) or a ß2-AR antagonist (butoxamine) 5 minutes before bicuculline. RESULTS: ß2-AR stimulation fully prevents limbic seizures induced by bicuculline micro-infusion in AT. Conversely, antagonism at ß2-AR worsens bicuculline-induced seizure severity and prolongs seizure duration, leading to self-sustaining status epilepticus. These data indicate a specific role for ß2-AR as an anticonvulsant in AT. CONCLUSION: NA counteracts limbic seizures. This relies on various receptors in different brain areas. The anterior piriform cortex plays a key role in patients affected by limbic epilepsy. The anticonvulsant effects of NA through ß2-AR may be related to the stimulation of the autophagy pathway. Recent literature and present data draw a perspective where ß2-AR stimulation while stimulating autophagy mitigates limbic seizures, focally within AT. The mechanism linking ß2-AR to autophagy and seizure modulation should be extensively investigated.

Central Phoenixin Protective Role on Pentylenetetrazol-Induced Seizures during Various Stages of the Estrous Cycle among Rats.

It is known that phoenixin-14 (PNX-14) has a mediatory role in reproduction; however, there is no report on the role of the PNX-14 on epilepsy. Therefore, this study aimed to investigate the antiepileptic effects of the PNX-14 on the pentylenetetrazol (PTZ)-induced epilepsy in the stages of the estrous cycle among rats. A total of 168 adult female Wistar rats were randomly divided into seven groups, including control (intracerebroventricular injection was performed with saline), PNX-14 (5 µg), PNX-14 (10 µg), bicuculline (competitive antagonist of GABAA receptors; 5 nmol)+PNX-14 (5 µg), bicuculline (BIC) (5 nmol)+PNX-14 (10 µg), saclofen (competitive antagonist of GABAB receptors; 2.5 µg)+PNX-14 (5 µg), and saclofen (2.5 µg)+PNX-14 (10 µg) in proestrus, estrus, metestrus, and diestrus. Afterward, the control and treatment groups were followed by intraperitoneal administration of 80 mg/kg PTZ. Initiation time of myoclonic seizures (ITMS), initiation time of tonic-clonic seizures (ITTS), seizure duration (SD), and mortality rate (MR) were monitored and recorded for 30 min. According to the results, PNX-14 alone significantly reduced the SD and seizure mortality in all phases of estrus (P<0.05). The injection of PNX-14 with BIC significantly reduced SD and seizure mortality in all estrus phases (P<0.05). PNX-14 alone increased both ITMS and ITTS in all phases of estrus (P<0.05). Furthermore, the injection of PNX-14 with BIC significantly reduced the effects of the PNX-14 on ITMS and ITTS in all estrus stages (P<0.05). These results showed that the antiepileptic activity of PNX-14 was probably mediated by GABAA receptors, and this effect was more prominent during the luteal phase than the follicular phase.

Sakuranetin exerts anticonvulsant effect in bicuculline-induced seizures.

Epilepsy is a chronic neurological disorder characterized by an abnormal, spontaneous, and synchronized neuronal hyperactivity. Therapeutic approaches for controlling epileptic seizures are associated with pharmacoresistance and side effects burden. Previous studies reported that different natural products may have neuroprotector effects. Sakuranetin (SAK) is a flavanone with antiparasitic, anti-inflammatory, antimutagenic, antiallergic, and antioxidant activity. In the present work, the effect of SAK on seizures in a model of status epilepticus induced by bicuculline (BIC) in mice was evaluated. Male Swiss mice received an intracerebroventricular injection (i.c.v.) of SAK (1, 10, or 20 mg/kg-SAK1, SAK10, or SAK20). Firstly, animals were evaluated in the open field (OF; 20 min), afterwards in the elevated plus maze (EPM) test (5 min). Next, 30 min prior the administration of BIC (1 mg/kg), mice received an injection of SAK (1 or 10 mg/kg, i.c.v.) and were observed in the OF (20 min) for seizures assessment. After behavioral procedures, immunohistochemical analysis of c-Fos was performed. Our main results showed that the lowest doses of SAK (1 and 10 mg/kg) increased the total distance traveled in the OF, moreover protected against seizures and death on the BIC-induced seizures model. Furthermore, SAK treatment reduced neuronal activity on the dentate gyrus of the BIC-treated animals. Taken together, our results suggest an anticonvulsant effect of SAK, which could be used for the development of anticonvulsants based on natural products from herbal source.

Convulsive responses to seizure-inducible drugs are exacerbated in progranulin-deficient mice.

Progranulin (PGRN) is a glycoprotein that is widely expressed among organs, including the central nervous system. PGRN insufficiency is involved in various neurodegenerative disorders such as frontotemporal dementia, Alzheimer's disease, and neuronal ceroid lipofuscinosis. One of the major causes of neuronal damage is hyperactivation of the cerebrum triggered by upregulation of excitatory systems. In the present study, we examined the possible involvement of PGRN in modulating excitability of the cerebrum using wild type and PGRN-deficient mice. First, we treated wild type and PGRN-deficient mice with seizure-inducible drugs, bicuculline or N-methyl-D-aspartate (NMDA), which provoke hyperexcitement of neurons. PGRN-deficient mice showed higher intensity of seizure and longer duration of convulsive behavior when treated with either bicuculline or NMDA. Next, we quantified the expression of NMDA receptor subunits in the hippocampus and cerebral cortex. The expression level of NR2A subunit protein was significantly higher in the hippocampus of PGRN-deficient mice, while no difference was observed in the cerebral cortex. On the other hand, mRNA levels of NMDA receptor subunits in the hippocampus were comparable or even lower in PGRN-deficient mice. These results suggest that PGRN modulates the excitability of the cerebrum by regulating at least partially the protein level of NMDA receptors in the hippocampus.

Neonatal blockade of GABA-A receptors alters behavioral and physiological phenotypes in adult mice.

Gamma-aminobutyric acid (GABA) plays an inhibitory role in the mature brain, and has a complex and bidirectional effect in different parts of the immature brain which affects proliferation, migration and differentiation of neurons during development. There is also increasing evidence suggesting that activation or blockade of the GABA-A receptors during early life can induce brain and behavioral abnormalities in adulthood. We investigated whether neonatal blockade of the GABA-A receptors by bicuculline can alter anxiety- and depression-like behaviors, body weight, food intake, corticosterone and testosterone levels in adult mice (postnatal days 80-95). To this end, neonatal mice were treated with either DMSO or bicuculline (70, 150 and 300µg/kg) during postnatal days 7, 9 and 11. When grown to adulthood, mice were exposed to behavioral tests to measure anxiety- (elevated plus-maze and light-dark box) and depression-like behaviors (tail suspension test and forced swim test). Stress-induced serum corticosterone and testosterone levels, body weight and food intake were also evaluated. Neonatal bicuculline exposure at dose of 300µg/kg decreased anxiety-like behavior, stress-induced corticosterone levels and increased testosterone levels, body weight and food intake, without significantly influencing depression-like behavior in adult male mice. However, no significant changes in these parameters were observed in adult females. These findings suggest that neonatal blockade of GABA-A receptors affects anxiety-like behavior, physiological and hormonal parameters in a sex-dependent manner in mice. Taken together, these data corroborate the concept that GABA-A receptors during early life have an important role in programming neurobehavioral phenotypes in adulthood.

Lunasin-induced behavioural effects in mice: focus on the dopaminergic system.

The present study for the first time is devoted to identify central effects of synthetic lunasin, a 43 amino acid peptide. A markedly expressed neuroleptic/cataleptic effect was observed at low (0.1-10 nmol/mouse) centrally administered doses in male C57Bl/6 mice. Lunasin considerably reduced the amphetamine hyperlocomotion but weakly apomorphine climbing behaviour. No influence on ketamine and bicuculline effects was observed. Binding assay studies demonstrated modest affinity of lunasin for the dopamine D1 receptor (Ki=60 ± 15 µM). In a functional assay of cAMP accumulation on live cells lunasin antagonised apomorphine effect on D1 receptor activation (pEC50=6.1 ± 0.3), but had no effect in cells expressing D2 receptors. The obtained data suggest that lunasin's action at least in part is provided via dopaminergic D1 receptor pathways. However, other non-identified mechanisms (probably intracellular) may play an important role in lunasin's central action. Nevertheless further studies of lunasin are promising, particularly taking into account a necessity for novel type of antipsychotic drugs.

Anticonvulsant action of indazole.

Here we report that indazole is characterized as a potential anticonvulsant, inhibiting pentylenetetrazole-, electroshock- and strychnine-induced convulsions in mice (ED50's: 39.9, 43.2 and 82.4 mg/kg, respectively) but not bicuculline- and picrotoxin-induced convulsions. The median toxic dose (TD(50)) of indazole was 52.3 mg/kg by the minimal motor impairment test. Therefore, nontoxic doses produced anticonvulsant activity against pentylenetetrazole- and electroshock-induced seizures. Indazole (50 mg/kg) had no effect on spontaneous activity but induced hypothermia. It also inhibited the metabolism of dopamine and 5-hydroxytryptamine in the brain in vivo and the activities of monoamine oxidase A and B in vitro, with IC(50) values of 20.6 µM and 16.3 µM, respectively. However, these inhibitory effects do not account for the anticonvulsant activity because treatment with typical monoamine oxidase inhibitors such as pargyline or tranylcypromine did not completely reproduce the anticonvulsant activity of indazole. In the animal seizure models tested, the anticonvulsant profile of indazole most resembled that of gabapentin and somewhat resembled those of the AMPA/kainate antagonist NBQX and the sodium channel inhibitor phenytoin, but differed from that of benzodiazepine. The isobolographic analyses showed that the interactive mode of indazole with gabapentin, NBQX or phenytoin is additive. These results suggest that indazole has anticonvulsant activity and multiple mechanisms.

Cerebral microcirculatory responses of insulin-resistant rats are preserved to physiological and pharmacological stimuli.

OBJECTIVE: Previously, we have shown that IR impairs the vascular reactivity of the major cerebral arteries of ZO rats prior to the occurrence of Type-II diabetes mellitus. However, the functional state of the microcirculation in the cerebral cortex is still being explored. METHODS: We tested the local CoBF responses of 11-13-week-old ZO (n = 31) and control ZL (n = 32) rats to several stimuli measured by LDF using a closed cranial window setup. RESULTS: The topical application of 1-100 µm bradykinin elicited the same degree of CoBF elevation in both ZL and ZO groups. There was no significant difference in the incidence, latency, and amplitude of the NMDA-induced CSD-related hyperemia between the ZO and ZL groups. Hypercapnic CoBF response to 5% carbon-dioxide ventilation did not significantly change in the ZO compared with the ZL. Topical bicuculline-induced cortical seizure was accompanied by the same increase of CoBF in both the ZO and ZL at all bicuculline doses. CONCLUSIONS: CoBF responses of the microcirculation are preserved in the early period of the metabolic syndrome, which creates an opportunity for intervention to prevent and restore the function of the major cerebral vascular beds.

Spatial and temporal properties of tic-related neuronal activity in the cortico-basal ganglia loop.

Motor tics are involuntary brief muscle contractions that interfere with ongoing behavior and appear as a symptom in several human disorders. While the pathophysiology of tics is still largely unknown, multiple lines of evidence suggest the involvement of the corticobasal ganglia loop in tic disorders. We administered local microinjections of bicuculline into the putamen of Macaca fascicularis monkeys to induce motor tics, while simultaneously recording neuronal activity from the primary motor cortex, putamen, and globus pallidus. These data were used to explore the spatial and temporal properties of tic-related neuronal activity within the cortico-basal ganglia system. In the putamen, tics were associated with brief bursts of activity of phasically active neurons (presumably the projection neurons) and complex excitation-inhibition patterns of tonically active neurons. Tic-related activity within the putamen was spatially focused and somatotopically organized. In the globus pallidus, tic-related activity was diffusely distributed throughout the motor territory. Tic-related activity in the putamen usually preceded the tic-related activations in the cortex, but in the globus pallidus, tic-related activity was mostly later than the cortex. These findings shed new light on the role of the different basal ganglia nuclei in the generation of motor tics. Despite the early and somatotopically focused nature of tic-related activity in the input stage of the basal ganglia, tic-related activity in the output nucleus is temporally late and diffusely distributed, making it incompatible with a role in tic initiation. Instead, abnormal basal ganglia activity may serve to modulate motor patterns or activate learning mechanisms, thus augmenting further tic expression.

Synthesis and anticonvulsant activity of 7-phenyl-6,7-dihydro-[1,2,4]triazolo[1,5-a]pyrimidin-5(4H)-ones and their derivatives.

Herein, we described the syntheses and anticonvulsant activities of 7-(substituted-phenyl)-6,7-dihydro-[1,2,4]triazolo[1,5-a]pyrimidin-5(4H)-ones (1a-1o) and their derivatives. Most of the synthesized compounds exhibited potent anticonvulsant activities in the maximal electroshock test (MES). The most promising compound 1i showed significant anticonvulsant activity in MES test with ED(50) value of 19.7 mg/kg. It displayed a wide margin of safety with protective index much higher than the standard drugs. In addition, the potence of compound 1i against seizures induced by Pentylenetetrazole, Isoniazid, Thiosemicarbazide, 3-Mercaptopropionic acid, and Bicuculline in the chemical-induced seizure tests suggested that compound 1i displayed broad spectrum activity in several models, and it is likely to have several mechanisms of action including inhibiting voltage-gated ion channels and modulating GABAergic activity.

Dose-dependent protective effect of connexin43 mimetic peptide against neurodegeneration in an ex vivo model of epileptiform lesion.

Epileptic seizures typically result in delayed neuronal loss secondary to the initial damage and an up-regulation in connexin43 (Cx43). This study investigated the role of Cx43 gap junctions in lesion spread and cell loss following epileptiform activity. Epileptiform injury in hippocampal slice cultures was induced by 48 h exposure to 100 µM bicuculline methochloride (BMC). During the 24h recovery period following BMC treatment, lesion spread was observed in the CA1. A Cx43 mimetic peptide, applied during either the BMC treatment or recovery periods, produced concentration- and exposure time-dependent neuroprotection, as measured by propidium iodide uptake at the end of the recovery period. During the BMC period, peptide concentrations between 5 and 50 µM (sufficient to block hemichannels) had a protective effect while a substantial gap junction blockade with 500 µM peptide exacerbated the lesion. By contrast, all doses applied during the recovery period protected the CA1 region from further damage. The results indicate that while the slices are undergoing excessive neuronal firing and epileptic stress, gap junction communication appears to be essential for tissue survival but hemichannel opening may be damaging. Following epileptiform insult, however, gap junction communication plays a crucial role in the spread of neuronal damage. The findings from this study identify gap junction communication as a potential therapeutic target for epilepsy.

GABA(A) ρ receptor mechanisms in the rat amygdala and its role in the modulation of fear and anxiety.

RATIONALE: Accumulating evidence for the presence of GABA(A) ρ receptors within the amygdala which differ from other members of the GABA(A) receptor family in both subunit composition and functional properties has been recently obtained. OBJECTIVES: This work was conducted to study whether GABA(A) ρ receptors may have a putative role in the amygdaloid modulation of fear and anxiety. RESULTS: It was found that the bilateral intra-amygdaloid administration (6-240 pmol/side) of (1,2,5,6-tetrahydropyridine-4-yl)methylphosphinic acid, a selective GABA(A) ρ receptor antagonist, reduced dose-dependently the exploration of the open arms of the elevated plus-maze without affecting locomotion and increased the plasma levels of corticosterone. In contrast, bicuculline in the dose range used (1.8-60 pmol/side) induced seizures, but had no effects on the exploration of the maze. CONCLUSIONS: It is suggested that GABA(A) ρ receptors may have a role in the amygdaloid modulation of fear and anxiety.

Epileptic seizures increase circulating endothelial cells in peripheral blood as early indicators of cerebral vascular damage.

Circulating endothelial cells (CECs) are nonhematopoetic mononuclear cells in peripheral blood that are dislodged from injured vessels during cardiovascular disease, systemic vascular disease, and inflammation. Their occurrence during cerebrovascular insults has not been previously described. Epileptic seizures cause the long-term loss of cerebrovascular endothelial dilator function. We hypothesized that seizures cause endothelial sloughing from cerebral vessels and the appearance of brain-derived CECs (BCECs), possible early indicators of cerebral vascular damage. Epileptic seizures were induced by bicuculline in newborn pigs; venous blood was then sampled during a 4-h period. CECs were identified in the fraction of peripheral blood mononuclear cells by the expression of endothelial antigens (CD146, CD31, and endothelial nitric oxide synthase) and by Ulex europeaus lectin binding. In control animals, few CECs were detected. Seizures caused a time-dependent increase in CECs 2-4 h after seizure onset. Seizure-induced CECs coexpress glucose transporter-1, a blood-brain barrier-specific glucose transporter, indicating that these cells originate in the brain vasculature and are thus BCECs. Seizure-induced BCECs cultured in EC media exhibited low proliferative potential and abnormal cell contacts. BCEC appearance during seizures was blocked by a CO-releasing molecule (CORM-A1) or cobalt protoporphyrin (heme oxygenase-1 inducer), which prevented apoptosis in cerebral arterioles and the loss of cerebral vascular endothelial function during the late postictal period. These findings suggest that seizure-induced BCECs are injured ECs dislodged from cerebral microvessels during seizures. The correlation between the appearance of BCECs in peripheral blood, apoptosis in cerebral vessels, and the loss of postictal cerebral vascular function suggests that BCECs are early indicators of late cerebral vascular damage.

Anticonvulsant effects of Searsia dentata (Anacardiaceae) leaf extract in rats.

Searsia species are used in South Africa to treat epilepsy. Previous studies have demonstrated an in vitro N-methyl-D-aspartic acid (NMDA) receptor antagonistic effect of the ethanolic leaf extract. The aim of this study was to evaluate the potential anticonvulsant properties of the ethanolic extract of S. dentata in various animal models of epilepsy. The extract was submitted to a screening in anticonvulsant assays including NMDA-, kainic acid (KA)-, pentylenetetrazol (PTZ)- and bicuculline (BIC)-induced seizures in rats. The extract protected 47% of the PN 18 Wistar pups (postnatal day 18, date of birth PN 0) (p < 0.05, n > 10) against NMDA-induced seizures and significantly delayed the onset of PTZ-induced seizures (p < 0.05, n > 8) at a dose of 250 mg/kg. A dose optimum was detected at 500 mg/kg for protection against KA-(63% protection, p < 0.05, n > 8) and BIC-induced seizures (50% protection, p < 0.05, n > 8) in young adult and PN 18 rats, respectively. The ethanolic extract of S. dentata showed anticonvulsive properties in several models of epilepsy. These results are compatible with previous findings of NMDA receptor antagonism. Due to the complex composition of the extract, the effect might be caused by more than one compound.

Dysfunction of the subthalamic nucleus induces behavioral and movement disorders in monkeys.

High-frequency stimulation of the subthalamic nucleus (STN) in parkinsonian patients is reported to induce psychiatric effects. The likely explanation for these effects is the partitioning of the STN into sensorimotor, associative, and limbic anatomo-functional territories. Thus, a specific neuronal dysfunction of the STN sensorimotor territory could lead to abnormal movements, whereas a dysfunction of the associative or limbic territory could lead to behavioral disturbances. To test this hypothesis, neuronal dysfunction of the STN was induced by microinjections of the GABA agonist muscimol, or antagonist bicucculline, in various parts of the nucleus in three monkeys. Stereotyped behaviors (licking and biting fingers) and/or violent hyperactivity were obtained with bicuculline injected into the anteromedial, associative, and limbic territories, whereas injections of muscimol induced no major effects. Abnormal limb movements (contralateral ballism) were obtained after muscimol or bicuculline injections into the posterolateral, sensorimotor territory. Control injections localized around the STN induced other effects (mainly torticollis), which underlines the specificity of STN injection effects. Our study supports the hypothesis that the anteromedial part of the STN is involved in behavioral control.

Cholecystokinin-8 sulfate modulates the anticonvulsant efficacy of vigabatrin in an experimental model of partial complex epilepsy in the rat.

PURPOSE: We evaluated the possible additive effect induced by the administration of the anticonvulsant vigabatrin (VGB) and cholecystokinin-8 sulfate (CCK-8S) on an experimental model of partial complex seizures (maximal dentate gyrus activation, MDA). Moreover, the functional involvement of gamma-aminobutyric acid (GABA) neurotransmission was tested by iontophoretically administering bicuculline (GABA receptor antagonist) in the dentate gyrus. METHODS: Urethane anesthetized rats were pretreated with VGB (50, 100 or 200 mg/kg, i.p.) or CCK-8S (8 nmol/kg, i.p.) alone or coadministered with VGB (50 mg/kg, i.p.). Dentate gyrus epileptic activity was obtained through the repetitive electrical stimulation of the angular bundle. MDA latency, duration, and poststimulus afterdischarge (AD) duration were evaluated. The extracellular activity of some dentate neurons was recorded before and during bicuculline iontophoresis. RESULTS: Only the higher dose of VGB reduced the mean duration of dentate MDA and AD. CCK-8S significantly decreased the number of animals exhibiting MDA responses, characterized by increased latency and shorter duration. The coadministration of CCK-8S and VGB (50 mg/kg) significantly increased the anticonvulsant effects, either reducing the number of responding animals or decreasing both MDA and AD durations. During bicuculline iontophoresis, all the modifications induced on the MDA-related activity of dentate neurons by the pretreatments (VGB and/or CCK-8S) were abolished. DISCUSSION: The results indicate that CCK-8S significantly enhances the VGB-induced anticonvulsant effect in the MDA model of partial epilepsy, probably through an increase of GABA cerebral levels. Such increased anticonvulsant effect becomes evident by using VGB at a lower dose.

Differential dietary ethanol intake and blood ethanol levels in adolescent and adult rats: effects on anxiety-like behavior and seizure thresholds.

BACKGROUND: Adult rats exhibit increased anxiety-like behavior after exposure to repeated cycles of chronic ethanol and withdrawal. While adolescent rats have differential responses to both acute and chronic ethanol treatments, the potential differences in the effects of repeated withdrawals in this population have yet to be determined. METHODS: Male adult and adolescent rats received three 5-day cycles of either a 4.5% or 7% ethanol diet (ED) separated by two 2-day withdrawal periods. Five hours into the final withdrawal, rats were tested for social interaction (SI) deficits (an index of anxiety-like behavior) and then assessed for seizure thresholds (audiogenic and bicuculline-induced). Ethanol intake was monitored throughout, and blood ethanol concentrations (BEC) were obtained from a separate group of rats. RESULTS: Adolescent rats have reduced SI during the final withdrawal from either ED and exhibit a greater reduction in SI compared to adult rats when exposed to a 7%ED. Audiogenic seizures were not increased during withdrawal from either ED in adult rats, but adolescent rats that received 7%ED displayed increased seizures. The bicuculline seizure thresholds were decreased in both ages exposed to a 7%ED, but only adolescent rats showed this decreased threshold after 4.5%ED. Ethanol intakes and BECs were higher in adolescent rats compared to similarly treated adults. However, ethanol intakes and BECs were comparable between 4.5%ED-treated adolescent and 7%ED-treated adult rats. CONCLUSIONS: Behavioral results from the 7%ED-treated groups suggested that adolescent rats may be more vulnerable to repeated withdrawals from ethanol than adults; however, differences in ethanol intake and BECs may be at least in part responsible. When ethanol intakes and BECs were similar between 4.5%ED-treated adolescent and 7%ED-treated adult rats, behavioral effects were not different. Importantly, these data illustrated that adolescent rats can exhibit anxiety and reduced seizure thresholds following this repeated withdrawal paradigm.

Visualizing localized dynamic changes during epileptic seizure onset in vivo with diffuse optical tomography.

Diffuse optical tomography (DOT) is a promising functional imaging modality due to its ability to provide quantitative and dynamic tomographic imaging of brain functions. This pilot study was conducted to demonstrate that DOT can be used to visualize the changes in local hemodynamics during seizures. The focal seizure was induced by microinjection of 10 microl of 1.9 mM GABAA antagonist bicuculline methiodide (BMI) into the left parietal neocortex of male Harlen Sprague-Dawley rats, which was imaged by a multispectral continuous-wave DOT system. Functional images were obtained by our finite element based image reconstruction algorithm. A series of dynamic 2D images were obtained to delineate the time course of concentration changes of oxyhaemoglobin, deoxyhaemoglobin, and total hemoglobin in the rat brain during seizure onset. The BMI induced epileptic foci were localized and observed over time from the images obtained. Our results suggest that diffuse optical tomography may be a promising modality for epilepsy imaging due to its ability to localize epileptic foci as well as its potential to map the functional activity in the area of human cerebral cortex in planning of epilepsy surgery.

Anticonvulsant effect of Persea americana Mill (Lauraceae) (Avocado) leaf aqueous extract in mice.

Various morphological parts of Persea americana Mill (Lauraceae) (avocado) are widely used in African traditional medicines for the treatment, management and/or control of a variety of human ailments, including childhood convulsions and epilepsy. This study examined the anticonvulsant effect of the plant's leaf aqueous extract (PAE, 50-800 mg/kg i.p.) against pentylenetetrazole (PTZ)-, picrotoxin (PCT)- and bicuculline (BCL)-induced seizures in mice. Phenobarbitone and diazepam were used as reference anticonvulsant drugs for comparison. Like the reference anticonvulsant agents used, Persea americana leaf aqueous extract (PAE, 100-800 mg/kg i.p.) significantly (p < 0.05-0.001) delayed the onset of, and antagonized, pentylenetetrazole (PTZ)-induced seizures. The plant's leaf extract (PAE, 100-800 mg/kg i.p.) also profoundly antagonized picrotoxin (PCT)-induced seizures, but only weakly antagonized bicuculline (BCL)-induced seizures. Although the data obtained in the present study do not provide conclusive evidence, it would appear that 'avocado' leaf aqueous extract (PAE) produces its anticonvulsant effect by enhancing GABAergic neurotransmission and/or action in the brain. The findings of this study indicate that Persea americana leaf aqueous extract possesses an anticonvulsant property, and thus lends pharmacological credence to the suggested ethnomedical uses of the plant in the management of childhood convulsions and epilepsy.