Basic and Clinical Neuroscience
Volume:5 Issue: 3, Summer 2014

The most common interpretation for the mechanisms of antidepression is the increase of the brain monoamine levels such as dopamine (DA). The increase of DA can reduce depression but it can also decrease the monoamine release because of autoreceptor inhibition. Although bupropion can decrease the dopamine release, there is evidence about stimulatory effects of chronic application of bupropion on ventral tegmental area (VTA) neurons. In this study, the intra-VTA acute microinfusion of bupropion on putative VTA non-Dopaminergic (VTA-nonDA) neuronal firing rates was evaluated by a single neuron recording technique. Animals were divided into 7 groups (sham, and 6 bupropion-microinfused groups with 1, 10-1, 10-2, 10-3, 10-4, and 10-5 mol, 1 μl/3 min, intra-VTA). A single neuron recording technique was done according to the stereotaxic coordination. After 10 min baseline recording, ACSF or bupropion was microinfused. The recording continued to recovery period in the treated groups. The prestimulus time (PST) and interspike interval (ISI) histograms were calculated for every single unit. The assessment of the drug effect was carried out by one-way analysis of variance (ANOVA) and Post-hoc test. 126 non-DA neurons were separated. Bupropion could inhibit 116 neurons and 11 neurons had no significant response. Maximum inhibition was 79.1% of baseline firing rate with 44.3 min duration. The inhibitory effect of bupropion was dose-dependent. The acute inhibitory effects of bupropion on VTA-nonDA neurons can explain the fast inhibitory effects of bupropion and other antidepressants on the VTA. These data can explain some side effects of antidepressants.

We investigated the role of ATP-sensitive potassium channels and L-type calcium channels in morphine-induced hyperalgesia after nociceptive sensitization. We used a hotplate apparatus to assess pain behavior in male NMRI mice. Nociceptive sensitization was induced by three days injection of morphine and five days of drug free. On day 9 of the schedule, pain behavior test was performed for evaluating the effects of morphine by itself and along with nimodipine, a blocker of L-type calcium channels and diazoxide, an opener of ATP-sensitive potassium channels. All drugs were injected through an intraperitoneal route. The results showed that morphine (7.5, 10 and 15 mg/kg) induced analgesia in normal mice, which was prevented by naloxone (1 mg/kg). After nociceptive sensitization, analgesic effect of morphine (10 and 15 mg/kg) was significantly decreased in sensitized mice. The results showed that nimodipine (2.5, 5, 10 and 20 mg/kg) had no significant effect on pain behavior test in either normal or sensitized mice. However, nimodipine (20 mg/ kg) along with morphine (10 and 15 mg/kg) caused more decrease in morphine analgesia in sensitized mice. Furthermore, diazoxide by itself (0.25, 1, 5 and 20 mg/kg) had also no significant effect on pain behavior in both normal and sensitized mice, but at dose of 20 mg/kg along with morphine (10 and 15 mg/kg) decreased analgesic effect of morphine in sensitized mice. It can be concluded that potassium and calcium channels have some roles in decrease of analgesic effect of morphine after nociceptive sensitization induced by pretreatment of morphine.

Regarding chronic nature of epilepsy and its side effects and to access the effective treatment procedures, herbal medicine has received remarkable interest. The aim of this study was to determine the anticonvulsant effects of hydro-alcoholic extract of Anethum graveolens seed on pentylenetetrazol (PTZ) -induced seizure in male mice. Fifty-six albino male mice were divided randomly into seven groups including the negative control (saline), positive control (Phenobarbital) and treatment groups using different doses of hydro-alcoholic extract of Anethum graveolens seed (50, 100, 300, 500 and 1000 mg/ kg). To provoke convulsion, PTZ was injected to all groups and initiation time of myoclonic and tonic-clonic seizures as well as surveillance after 24 h were measured. The results indicated that hydro-alcoholic extract of Anethum graveolens seed (AGS) delayed the initiation time of myoclonic and tonic-clonic seizures in comparison with saline group. The latency was considerable for myoclonic and tonic-clonic seizures at all above mentioned doses of AGS extract except for the lowest one. Moreover, the protective effect of AGS extract against mortality was statistically significant at all doses except for 50 mg/kg. As the hydro-alcoholic extract of AGS showed an appropriate response in experimental model of convulsion, it might be considered as an adjuvant therapy with other traditional antiepileptic medications.

Direction and latency of electrical connectivity between different sites of brain explains brain neural functionality. We compared efficiency of cross correlation and phase locking methods in time lag estimation which are based on local field potential (LFP) and LFPspike signals, respectively. Signals recorded from MT area of a macaque’s brain was used in a simulation approach. The first signal was real brain activity and the second was identical to the first one, but with two kinds of delayed and not delayed forms. Time lag between two signals was estimated by cross correlation and phase locking methods. Both methods estimated the time lags with no errors. Phase locking was not as time efficient as correlation. In addition, phase locking suffered from temporal self bias. Correlation was a more efficient method. Phase locking was not considered as a proper method to estimate the time lags between brain sites due to time inefficiency and self bias, the problems which are reported for the first time about this method.

A number of research studies have shown that the new generation of neuroleptic medications can more effectively contribute to treating negative symptoms of schizophrenia compared with the first generation by influence cognitive functioning. The present study examined the therapeutic effectiveness of manufactured Risperidone and Haloperidol in Iran on treating the negative symptoms of schizophrenia. This randomized clinical trial (RCT) study examined 100 hospitalized patients who met DSM-IV. TR criteria for schizophrenia were sampled at Razi psychiatric hospital in Tehran, Iran. After two weeks of stopping neuroleptic medications, the patients were randomly assigned into two groups, Risperidone and Haloperidol group. During 8 weeks of the study, baseline and weekly assessments were performed by completing brief psychiatric report scale (BPRS). Both Risperidone and Haloperidol were effective in treating the negative symptoms of schizophrenia and improvements in both groups were initiated in the second week of treatment. The most prominent response rate was the second week in Haloperidol group and the eighth week in Risperidone group but this difference was not statistically significant. Prescribing Risperidone or Haloperidol for treating negative symptoms of schizophrenia can be influenced by other criteria including side effects, previous treatment histories of patients and their families and a patient`s or physician` preference in prescribing a medication. Studies in other countries show that Haloperidol has better therapeutic effects in treating the negative symptoms of schizophrenia in comparison with Risperidone. Further studies on the therapeutic effectiveness of Risperidone and Haloperidol are suggested.

Anxiety is among the most common and treatable mental disorders. Adrenergic and cannabinoid systems have an important role in the neurobiology of anxiety. The elevated plus-maze (EPM) has broadly been used to investigate anxiolytic and anxiogenic compounds. The present study investigated the effects of intraperitoneal (IP) injection of cannabinoid CB1 receptor antagonist (AM251) in the presence of alpha-1 adrenergic antagonist (Prazosin) on rat behavior in the EPM. In this study, the data were obtained from male Wistar rat, which weighing 200- 250 g. Animal behavior in EPM were videotaped and saved in computer for 10 min after IP injection of saline, AM251 (0.3 mg/kg), Prazosin (0.3 mg/kg) and AM251 + Prazosin, subsequently scored for conventional indices of anxiety. During the test period, the number of open and closed arms entries, the percentage of entries into the open arms of the EPM, and the spent time in open and closed arms were recorded. Diazepam was considered as a positive control drug with anxiolytic effect (0.3, 0.6, 1.2 mg/kg). Diazepam increased the number of open arm entries and the percentage of spent time on the open arms. IP injection of AM251 before EPM trial decreased open arms exploration and open arm entry. Whereas, Prazosin increased open arms exploration and open arm entry. This study showed that both substances in simultaneous injection have conflicting effects on the responses of each of these two compounds in a single injection. Injection of CB1 receptor antagonist may have an anxiogenic profile in rat, whereas adrenergic antagonist has an anxiolytic effect. Further investigations are essential for better understanding of anxiolytic and anxiogenic properties and neurobiological mechanisms of action and probable interactions of the two systems.

Exposure to 3, 4- methylenedioxymethamphetamine (MDMA) could lead to serotonergic system toxicity in the brain. This system is responsible for learning and memory functions. Studies show that MDMA causes memory impairment dose-dependently and acutely. The present study was designed to evaluate the chronic and acute effects of MDMD on spatial memory and acquisition of passive avoidance. Adult male Wistar rats (200-250 g) were given single or multiple injections of MDMA (10 mg/kg, IP). Using passive avoidance and Morris Water Maze (MWM) tasks, learning and spatial memory functions were assessed. The data were analyzed by SPSS 16 software and one- way analysis of variance (ANOVA) test. Our results showed that there were significant differences in latency to enter the dark compartment (STL) between sham and MDMA- treated groups. Acute group significantly showed more STL in comparison with chronic group. Furthermore, MDMA groups spent more time in dark compartment (TDS) than the sham group. Administration of single dose of MDMA significantly caused an increase in TDS compared with the chronic group. In the MWM, MDMA treatment significantly increased the traveled distance and escaped latency compared to the sham group. Like to passive avoidance task, percentage of time spent in the target quadrant in MDMA- treated animals impaired in MWM compared with sham group. These data suggest that MDMA treatment impairs learning and memory functions that are more extensive in acute- treated rats.

Previous studies have demonstrated that the β-adrenergic receptor antagonist propranolol impairs fear memory reconsolidation in experimental animals. There are experimental parameters such as the age and the strength of memory that can interact with pharmacological manipulations of memory reconsolidation. In this study, we investigated the ability of the age and the strength of memory to influence the disrupting effects of propranolol on fear memory reconsolidation in rats. The rats were trained in a contextual fear conditioning using two (weak training) or five (strong training) footshocks (1mA). Propranolol (10mg/kg) injection was immediately followed retrieval of either a one-day recent (weak or strong) or 36-day remote (weak or strong) contextual fear memories. We found that propranolol induced a long-lasting impairment of subsequent expression of recent and remote memories with either weak or strong strength. We also found no memory recovery after a weak reminder shock. Furthermore, no significant differences were found on the amount of memory deficit induced by propranolol among memories with different age and strength. Our data suggest that the efficacy of propranolol in impairing fear memory reconsolidation is not limited to the age or strength of the memory.