Saffron and crocin ameliorate prenatal valproic acid-induced autistic-like behaviors and brain oxidative stress in the male offspring rats.

Autism is a neurobehavioral disease that induces cognitive and behavioral alterations, usually accompanied by oxidative stress in the brain. Crocus sativus (saffron) and its active ingredient, crocin, have potent antioxidative effects that may benefit autistic behaviors. This study aimed to determine the effects of saffron extract and crocin against brain oxidative stress and behavioral, motor, and cognitive deficits in an animal model of autism in male offspring rats. 14 female rats were randomly divided into the saline and valproic acid (VPA) groups. Then, they were placed with mature male rats to mate and produce offspring. VPA (500 mg/kg, i.p.) was injected on day 12.5 of pregnancy (gestational day, GD 12.5) to induce an experimental model of autism. 48 male pups were left undisturbed for 29 days. First-round behavioral tests (before treatments) were performed on 30-33 post-natal days (PND), followed by 28 days of treatment (PND 34-61) with saffron (30 mg/kg, IP), crocin (15 or 30 mg/kg, i.p.), or saline (2 ml/kg, i.p.). The second round of behavioral tests (after treatments) was performed on PND 62-65 to assess the effects of the treatments on behavioral and cognitive features. In the end, animals were sacrificed under deep anesthesia, and their brains were dissected to evaluate the brain oxidative stress parameters, including malondialdehyde (MDA), glutathione (GSH), and catalase (CAT). VPA injection into female rats increased anxiety-like behaviors, enhanced pain threshold, impaired motor functions, disturbed balance power, increased MDA, and decreased GSH and CAT in their male offspring. 28 days of treatment with saffron or crocin significantly ameliorated behavioral abnormalities, reduced MDA, and increased GSH and CAT levels. Brain oxidative stress has been implicated in the pathophysiology of autistic-like behaviors. Saffron and crocin ameliorate anxiety-like behaviors, pain responses, motor functions, and brain oxidative stress parameters in an experimental model of autism. Saffron and crocin may hold promise as herbal-based pharmacological treatments for individuals with autism. However, further histological evidence is needed to confirm their efficacy.

Prangos ferulacea (L.) ameliorates behavioral alterations, hippocampal oxidative stress markers, and apoptotic deficits in a rat model of autism induced by valproic acid.

BACKGROUND: Prenatal exposure to valproic acid (VPA) may enhance the risk of autism spectrum disorder (ASD) in children. This study investigated the effect of Prangos ferulacea (L.) on behavioral alterations, hippocampal oxidative stress markers, and apoptotic deficits in a rat model of autism induced by valproic acid. METHODS: Pregnant rats received VPA (600 mg/kg, intraperitoneally [i.p.]) or saline on gestational day 12.5 (E 12.5). Starting from the 30th postnatal day (PND 30), the pups were i.p. administered Prangos ferulacea (PF, 100 and 200 mg/kg), or the vehicle, daily until PND 58. On PND 30 and 58, various behavioral tasks were used to evaluate pups, including the open field, elevated plus-maze, hot-plate, and rotarod test. On PND 65, the animals were euthanized, and their brains were removed for histopathological and biochemical assay. RESULTS: Prenatal exposure to VPA caused significant behavioral changes in the offspring, reversed by administering an extract of Prangos ferulacea (L.). Additionally, prenatal VPA administration resulted in increased levels of malondialdehyde and deficits in antioxidant enzyme activities in the hippocampus, including catalase and glutathione, ameliorated by PF. Likewise, postnatal treatment with PF improved VPA-induced dysregulation of Bax and Blc2 in the hippocampus and reduced neuronal death in CA1, CA3, and dentate gyrus. CONCLUSION: The findings of this study suggest that postnatal administration of PF can prevent VPA-induced ASD-like behaviors by exhibiting antiapoptotic and antioxidant properties. Therefore, PF may have the potential as an adjunct in the management of ASD.

Hypothalamus and Post-Traumatic Stress Disorder: A Review.

Humans have lived in a dynamic environment fraught with potential dangers for thousands of years. While fear and stress were crucial for the survival of our ancestors, today, they are mostly considered harmful factors, threatening both our physical and mental health. Trauma is a highly stressful, often life-threatening event or a series of events, such as sexual assault, war, natural disasters, burns, and car accidents. Trauma can cause pathological metaplasticity, leading to long-lasting behavioral changes and impairing an individual's ability to cope with future challenges. If an individual is vulnerable, a tremendously traumatic event may result in post-traumatic stress disorder (PTSD). The hypothalamus is critical in initiating hormonal responses to stressful stimuli via the hypothalamic-pituitary-adrenal (HPA) axis. Linked to the prefrontal cortex and limbic structures, especially the amygdala and hippocampus, the hypothalamus acts as a central hub, integrating physiological aspects of the stress response. Consequently, the hypothalamic functions have been attributed to the pathophysiology of PTSD. However, apart from the well-known role of the HPA axis, the hypothalamus may also play different roles in the development of PTSD through other pathways, including the hypothalamic-pituitary-thyroid (HPT) and hypothalamic-pituitary-gonadal (HPG) axes, as well as by secreting growth hormone, prolactin, dopamine, and oxytocin. This review aims to summarize the current evidence regarding the neuroendocrine functions of the hypothalamus, which are correlated with the development of PTSD. A better understanding of the role of the hypothalamus in PTSD could help develop better treatments for this debilitating condition.

Corticosterone injection into the dorsal and ventral hippocampus impairs fear memory reconsolidation in a time-dependent manner in rats.

Reconsolidation is an active process induced following the reactivation of previously consolidated memories. Recent studies suggest brain corticosteroid receptors may participate in the modulation of fear memory reconsolidation. Glucocorticoid receptors (GRs), with 10-fold lower affinity than mineralocorticoid receptors (MRs), are mainly occupied during the peak of the circadian rhythm, and after stress, so they probably have a more critical role than MRs in memory phases during stressful situations. This study investigated the role of dorsal and ventral hippocampal (DH and VH) GRs and MRs on fear memory reconsolidation in rats. Male Wistar rats with surgically implanted bilaterally cannulae at the DH and VH were trained and tested in an inhibitory avoidance task. The animals received bilateral microinjections of vehicle (0.3 µl/side), corticosterone (3 ng/0.3 µl/side), the GRs antagonist RU38486 (3 ng/0.3 µl/side), or the MRs antagonist spironolactone (3 ng/0.3 µl/side) immediately after memory reactivation. Moreover, drugs were injected into VH 90 min after memory reactivation. Memory tests were performed 2, 9, 11, and 13 days after memory reactivation. Results indicated that injection of corticosterone into the DH but not VH immediately after memory reactivation significantly impaired fear memory reconsolidation. Moreover, corticosterone injection into VH 90 min after memory reactivation impaired fear memory reconsolidation. RU38486, but not spironolactone reversed these effects. These findings indicate that corticosterone injection into the DH and VH via GRs activation impairs the reconsolidation of fear memory in a time-dependent manner.

Glucocorticoid- ß-adrenoceptors interactions in the infralimbic cortex in acquisition and consolidation of auditory fear memory extinction in rats.

This study investigated the interactive effect of glucocorticoid and ß-adrenoceptors in the infralimbic (IL) cortex on the acquisition and consolidation of fear extinction in rats' auditory fear conditioning (AFC) task. On day 1, rats underwent habituation for 9 min (12 tones, 10 s, 4 kHz, 80 dB, without footshock). On day 2 (conditioning), rats received 3 mild electrical footshocks (US; 2 s, 0.5 mA) paired with the auditory-conditioned stimulus (CS; tone: 30 s, 4 kHz, 80 dB). On days 3-5 (Ext 1-3), rats received 15 tones with no footshock in the test box. Intra-IL injection of corticosterone (CORT, 20 ng/0.5 µl per side) before Ext 1 and after Ext 1-2, respectively, facilitated the acquisition and consolidation of fear memory extinction. Intra-IL injection of the ß2-adrenoceptor agonist clenbuterol (CLEN, 50 ng/0.5 µl per side) inhibited, but the ß-adrenoceptor antagonist propranolol (PROP, 500 ng/0.5 µl per side) enhanced the facilitatory effects of CORT on fear memory extinction. CORT injection before the acquisition of fear extinction increased p-ERK levels in the IL. Co-injection of CORT with CLEN increased, but PROP decreased p-ERK activities. CORT injection after the consolidation of fear extinction increased p-CREB in the IL. Co-injection of CORT with CLEN increased, but PROP reduced p-CREB activities. Our findings show that corticosterone facilitates the acquisition and consolidation of fear memory extinction. GRs and ß-adrenoceptors in the IL jointly regulate fear memory extinction via ERK and CREB signaling pathways. This pre-clinical animal study may highlight the effect of GRs and ß-adrenoceptors of the IL cortex in regulating fear memory processes in fear-related disorders such as PTSD.

Corticosterone injection into the infralimbic prefrontal cortex enhances fear memory extinction: Involvement of GABA receptors and the extracellular signal-regulated kinase.

This study investigated the interactive effect of glucocorticoid and Gamma-aminobutyric acid (GABA) receptors in the Infralimbic (IL) cortex on fear extinction in rats' auditory fear conditioning task (AFC). Animals received 3 conditioning trial tones (conditioned stimulus, 30 s, 4 kHz, 80 dB) co-terminated with a footshock (unconditioned stimulus, 0.8 mA, 1 s). Extinction testing was conducted over 3 days (Ext 1-3) after conditioning. Intra-IL injection of corticosterone (CORT, 20 ng/0.3 µl/side) was performed 15 min before the first extinction trial (Ext 1) which attenuated auditory fear expression in subsequent extinction trials (Ext 1-3), demonstrating fear memory extinction enhancement. Co-injection of the GABAA agonist muscimol (250 ng/0.3 µl/side) or the GABAB agonist baclofen (250 ng/0.3 µl/side) 15 min before corticosterone, did not significantly affect the facilitative effects of corticosterone on fear extinction. However, co-injection of the GABAA antagonist bicuculline (BIC, 100 ng/0.3 µl/side) or the GABAB antagonist CGP35348 (CGP, 100 ng/0.3 µl/side) 15 min before corticosterone, blocked the facilitative effects of corticosterone on fear extinction. Moreover, extracellular signal-regulated kinase (ERK) and cAMP response element-binding (CREB) in the IL were examined by Western blotting analysis after the first extinction trial (Ext 1) in some groups. Intra-IL injection of corticosterone increased the ERK activity but not CREB. Co-injection of the bicuculline or CGP35348 blocked the enhancing effect of corticosterone on ERK expression in the IL. Glucocorticoid receptors (GRs) activation in the IL cortex by corticosterone increased ERK activity and facilitated fear extinction. GABAA or GABAB antagonists decreased ERK activity and inhibited corticosterone's effect. GRs and GABA receptors in the IL cortex jointly modulate the fear extinction processes via the ERK pathway. This pre-clinical animal study may highlight GRs and GABA interactions in the IL cortex modulating fear memory processes in fear-related disorders such as post-traumatic stress disorder (PTSD).

ß-adrenoceptors of the infra-limbic cortex mediate corticosterone-induced enhancement of acquisition and consolidation of fear memory extinction in rats.

The extinction of auditory fear conditioning (AFC) refers to reducing the fear responses induced following repeated presentation of a conditioned stimulus (tone) in the absence of an unconditioned stimulus (electric foot shock). Glucocorticoid receptors (GRs) play an important role in extinction, but the underlying neurobiological mechanisms are unclear. This study aimed to investigate the interaction between glucocorticoids and ß-adrenoceptors of the infra-limbic cortex (IL) in regulating the acquisition and consolidation of fear memory extinction in rats. Male rats were trained to AFC and received three trial tones (30 s, 4 kHz, 80 dB) co-terminated with a footshock (0.8 mA, 1 s; unconditioned stimulus). Extinction trials were conducted over 3 days after training (Ext 1-3). In experiment 1, rats received clenbuterol (0.25 mg/kg/2 ml, IP) as a ß2-adrenoceptor agonist or propranolol (2.5 mg/kg/2 ml, IP) as a ß-adrenoceptors antagonist before Ext 1 and immediately after Ext 1 and Ext 2 followed by systemic injection of corticosterone (3 mg/kg/2 ml, IP). In Experiment 2, separate groups of rats received a bilateral intra-IL injection of clenbuterol (50 ng/0.5 µl/side) or propranolol (500 ng/0.5 µl/side) followed by a systemic injection of corticosterone (3 mg/kg/2 ml) before Ext 1 and immediately after Ext 1 and Ext 2. Results indicated that systemic and intra-IL injections of clenbuterol and propranolol inhibited and increased the facilitative effects of corticosterone on fear memory extinction, respectively. These findings show that activating ß-adrenergic receptors in the IL mediates glucocorticoid effects on the acquisition and consolidation of auditory-conditioned fear memory extinction.

Role of Amygdala-Infralimbic Cortex Circuitry in Glucocorticoid-induced Facilitation of Auditory Fear Memory Extinction.

Introduction: The basolateral amygdala (BLA) and infralimbic area (IL) of the medial prefrontal cortex (mPFC) are two interconnected brain structures that mediate both fear memory expression and extinction. Besides the well-known role of the BLA in the acquisition and expression of fear memory, projections from IL to BLA inhibit fear expression and have a critical role in fear extinction. However, the details of IL-BLA interaction have remained unclear. Here, we investigated the role of functional reciprocal interactions between BLA and IL in mediating fear memory extinction. Methods: Using lidocaine (LID), male rats underwent unilateral or bilateral inactivation of the BLA and then unilateral intra-IL infusion of corticosterone (CORT) prior to extinction training of the auditory fear conditioning paradigm. Freezing behavior was reported as an index for conditioned fear. Infusions were performed before the extinction training, allowing us to examine the effects on fear expression and further extinction memory. Experiments 1-3 investigated the effects of left or right infusion of CORT into IL and LID unilaterally into BLA on fear memory extinction. Results: Intra-IL infusion of CORT in the right hemisphere reduced freezing behavior when administrated before the extinction training. Auditory fear memory extinction was impaired by asymmetric inactivation of BLA and CORT infusion in the right IL; however, the same effect was not observed with symmetric inactivation of BLA. Conclusion: IL-BLA neural circuit may provide additional evidence for the contribution of this circuit to auditory fear extinction. This study demonstrates dissociable roles for right or left BLA in subserving the auditory fear extinction. Our finding also raises the possibility that left BLA-IL circuitry may mediate auditory fear memory extinction via underlying mechanisms. However, further research is required in this area. Highlights: Corticosterone infusion in the right (but not the left) infralimbic area facilitates auditory fear memory extinction.Corticosterone infusion in the right infralimbic area following symmetric basolateral amygdala inactivation has no effect on auditory fear memory extinction.Asymmetric basolateral amygdala inactivation prior to corticosterone infusion into the right infralimbic area impairs auditory fear memory extinction. Plain Language Summary: Previous studies have established that glucocorticoids, which are released in stressful conditions, enhance fear memory extinction. In this study, we found that corticosterone infusion into the right infralimbic area, but not the left one, facilitates auditory fear memory extinction. The effect of corticosterone infusion in the infralimbic area was not blocked by the intra-basolateral amygdala injections of lidocaine when administrated in the ipsilateral hemisphere. However, asymmetric basolateral amygdala inactivation and corticosterone infusion into the right infralimbic area impairs auditory fear memory extinction.

Pre-Ischemic Oxytocin Treatment Alleviated Neuronal Injury via Suppressing NF-κB, MMP-9, and Apoptosis Regulator Proteins in A Mice Model of Stroke.

Objective: This study was designed to determine the effects of pre-ischemic administration of oxytocin (OXT) on neuronal injury and possible molecular mechanisms in a mice model of stroke. Materials and Methods: In this experimental study, stroke was induced in the mice by middle cerebral artery occlusion (MCAO) for 60 minutes and 24 hours of reperfusion. OXT was given as intranasal daily for 7 consecutive days before ischemic stroke. Neuronal damage, spatial memory, and the expression levels of nuclear factor-kappa B (NF-κB), interleukin-1ß (IL-1ß), tumor necrosis factor-α (TNF-α), matrix metalloproteinase-9 (MMP-9), brain-derived neurotrophic factor (BDNF) and apoptosis were assessed 24 hours after stroke. Results: Pre-ischemic treatment with OXT significantly reduced the infarct size (P<0.01); but did not recover the neurological and spatial memory dysfunction (P>0.05). Moreover, OXT treatment considerably decreased the expressions of NF-κB, TNF-α, IL-1ß, and MMP-9 (P<0.001) and enhanced the level of BDNF protein. OXT treatment also significantly downregulated Bax expression and overexpressed Bcl-2 proteins. Conclusion: The finding of this study indicated that administration of OXT before ischemia could limit brain injury by inhibiting MMP-9 expression, apoptosis, inflammatory signaling pathways, and an increase in the BDNF protein level. We suggested that OXT may be potentially useful in the prevention and/or reducing the risk of the cerebral stroke attack, and could be offered as a new prevention option in the clinics.

Effects of different intensities of treadmill exercise on cued fear extinction failure, hippocampal BDNF decline, and Bax/Bcl-2 ratio alteration in chronic-morphine treated male rats.

Chronic morphine impairs cued fear extinction, which may contribute to the high prevalence of anxiety disorders and the replase of opiate addiction. This work investigated the effects of forced exercise with different intensities on cued fear extinction impairment and alternations of hippocampal BDNF and apoptotic proteins induced by chronic morphine. Rats were injected with bi-daily doses of morphine or saline for ten days and then received a cued or contextual fear conditioning training, which was followed by fear extinction training for four consecutive days. Cued, but the not contextual fear response was impaired in morphine-treated rats. Then, different saline or morphine-treated rats underwent forced exercise for 4-weeks with light, moderate or high intensities. Subsequently, rats received a cued fear conditioning followed by four days of extinction training, and the expression of hippocampal BDNF and apoptotic proteins was determined. A relatively long time after the last injection of morphine (35 days), rats again showed cued fear extinction failure and reduced hippocampal BDNF, which recovered by light and moderate, but not high exercise. Light and moderate, but not high-intensity treadmill exercise enhanced the up-regulation of Bcl-2 and down-regulation of the Bax proteins in both saline- and morphine-treated rats, which shifted the balance between pro-apoptotic and anti-apoptotic factors in favor of cell survival. These findings highlight the impact of exercise up to moderate intensity in the recovery of cued extinction failure, more likely via BDNF in addicted individuals.

Oxytocin in dorsal hippocampus facilitates auditory fear memory extinction in rats.

Fear extinction is impaired in some psychiatric disorders. Any treatment that facilitates the extinction of fear is a way to advance the treatment of related psychiatric disorders. Recent studies have highlighted the role of oxytocin (OT) in fear extinction, but the endogenous release of OT during fear extinction in the dorsal hippocampal (dHPC) is not clear. We investigated the release of OT during fear extinction and the role of the HPC - medial prefrontal cortex (mPFC) circuit and BDNF in the effects of exogenous OT on auditory fear conditioning in male rats. We found that the release of endogenous OT in the dHPC is significantly increased during the fear extinction process as measured by the microdialysis method. Increased freezing response in the OT-treated rats compared to saline-treated rats showed that exogenous OT in the dHPC enhanced the fear extinction. Injection of BDNF antagonist (ANA-12) into the infralimbic (IL) blocked the effect of exogenous OT on the dHPC. Following OT injection, BDNF levels increased in the dHPC, ventral HPC, and IL cortex; but decreased in the prelimbic cortex (PL). Finally, OT microinjected into the dHPC significantly increased neural activity of pyramidal neurons of the CA1-vHPC and IL but decreased the neural activity in the PL cortex. Our findings strongly support that the dHPC endogenous OT plays a crucial role in enhancing fear extinction. It seems that the activation of the HPC-mPFC pathway, and consequently, the release of BDNF in the IL cortex mediates the enhancing effects of OT on fear extinction.

Chronic light deprivation induces different effects on spatial and fear memory and hippocampal BDNF/TRKB expression during light and dark phases of rat diurnal rhythm.

Disruptions in light/dark cycle have been associated with an altered ability to form and retrieve memory in human and animals. Animal studies have shown that chronic light deprivation disrupts the light/dark cycle and alters the neural connections that mediate hippocampal memory formation. In order to better understand how light deprivation affects the formation and retrieval of memory in adult rats, we examined the effect of total darkness on spatial and auditory fear learning and memory formation and BDNF/TRKB protein levels during the light and dark phases of the rat circadian cycle. Male Wistar rats (n = 60), were randomly divided into two main groups: normal rearing (NR, 12 h light/dark cycle for 3 weeks) and dark rearing (DR, kept in constant darkness for 3 weeks); and each of these groups had a "light (day)" and "dark (night)" sub-group. After 3 weeks, the Morris Water maze and auditory fear conditioning were used to assess spatial and fear memory acquisition and retrieval, respectively. BDNF and TRKB protein levels in the hippocampus of rats from the four sub-groups were measured by Western blot, at the completion of the 3 week constant darkness exposure and after the behavioral experiments. These studies revealed that DR for 3 weeks impaired spatial memory retrieval and enhanced extinction of auditory fear memory specifically during the light (day) phase. DR also eliminated the normal fluctuations in BDNF/TRKB levels observed in the hippocampus across the light/dark cycle.

Neuroprotective Effects of Chemerin on a Mouse Stroke Model: Behavioral and Molecular Dimensions.

The present study was conducted to investigate the effects of different doses of recombinant human Chemerin (rhChemerin) on brain damage, spatial memory, blood-brain barrier (BBB) disruption and cellular and molecular mechanisms in a mouse stroke model. The mouse stroke model was developed by blocking the middle cerebral artery for 1 h and performing reperfusion for 23 h. Immediately, one and three hours after the stroke, 200, 400 and 800 ng/mouse of intranasal rhChemerin was administered. Neuronal and BBB damage, spatial memory and neurological performance were examined 24 h after the stroke. Western blotting and immunofluorescence were utilized to determine the effects of rhChemerin on the expressions of nuclear factor kappa B (NF-κB), pro-inflammatory cytokines such as TNF-α and IL-1ß, anti-inflammatory cytokines such as IL-10 and TGF-ß and vascular endothelial growth factor (VEGF). Administering 400 and 800 ng/mouse of rhChemerin in the mice immediately and one hour after ischemia minimized the infarct size, BBB opening, spatial memory and neurological impairment (P < 0.001). Furthermore, 800 ng/mouse of rhChemerin significantly diminished terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL)-positive (apoptotic) cells, suppressed the expressions of NF-kB, TNF-α and IL-1ß and upregulated IL-10 and VEGF in the cortex and hippocampus of the mice. The present findings showed that rhChemerin administered immediately and one hour after stroke alleviates neuronal and BBB injures and improves spatial memory. These effects of rhChemerin may be mediated by inhibiting inflammatory pathways and apoptotic machinery.

The Effects of Valerian on Sleep Quality, Depression, and State Anxiety in Hemodialysis Patients: A Randomized, Double-blind, Crossover Clinical Trial.

OBJECTIVES: Our study sought to determine the effects of valerian on sleep quality, depression, and state anxiety in hemodialysis (HD) patients. METHODS: This randomized, double-blind, placebo-controlled, crossover clinical trial was conducted on 39 patients undergoing HD allocated into a valerian and placebo group. In the first phase of the study, group A (n = 19) received valerian and group B (n = 20) received a placebo one hour before sleep every night for a total of one month. Sleep quality, state anxiety, and depression were assessed in the patients at the beginning and end of the intervention using the Pittsburgh Sleep Quality Index, the Spielberger State-Trait Anxiety Inventory, and Beck Depression Inventory. In the second phase, the two groups' treatment regimen was swapped. After a one-month washout period, the same process was repeated on the crossover groups (i.e., group A received placebo and group B received valerian). RESULTS: In the first phase, the mean sleep quality, depression, and state anxiety scores showed significant reductions in both groups, but the reduction was significantly higher in group A compared to group B (7.6 vs. 3.2, p< 0.001; 6.5 vs. 2.3, p =0.013; 14.6 vs. 7.3, p =0.003, respectively). In the second phase, the mean sleep disorder, depression, and state anxiety scores showed significant reductions in both groups, but the reduction was significantly lower in group A compared to group B (1.4 vs. 4.6, p< 0.001; 1.2 vs. 3.8, p =0.002; 1.5 vs. 6.2, p< 0.001, respectively). CONCLUSIONS: Valerian significantly improved sleep quality, the symptoms of state anxiety, and depression in HD patients.

Prophylactic effect of intranasal oxytocin on brain damage and neurological disorders in global cerebral ischemia in mice.

OBJECTIVES: A few experimental studies have shown the therapeutic effects of oxytocin on focal cerebral ischemia. In this study, the prophylactic effect of intranasal oxytocin on brain damage was investigated in a cerebral ischemic model. MATERIALS AND METHODS: Intranasal oxytocin (8 IU/per mouse) was prescribed daily for one week. Cerebral ischemia was performed through bilateral common carotid artery occlusion (BCCAO) for 20 min and then blood flow was restored for 24 hr. Finally, neurological disorders, spatial learning and memory, neuronal death, and neuronal apoptosis were assessed in CA1, CA3, and dentate gyrus. Also, levels of interleukin-1ß (IL-1ß) and Tumor necrosis factor-alpha (TNFα) were measured in the hippocampus. RESULTS: Induction of global ischemia leads to neurological disorders and impairment of spatial learning and memory that are improved by pre-treatment with oxytocin (P<0.01). Cresyl violet staining showed that pretreatment with oxytocin significantly reduced the number of dead nerve cells in CA1, CA3, and dentate gyrus by 40.7, 32, and 34.3%, respectively. Also, positive TUNEL cells in CA1, CA3, and dental gyrus decreased by 15, 30, and 27%, respectively. In addition, levels of TNFα and IL-1ß, which were extensively increased in ischemic mice, were significantly reduced with oxytocin pre-treatment. CONCLUSION: Pre-treatment of oxytocin reduces ischemic damage and improves neurological function and spatial memory. The neuroprotective effect of oxytocin is mediated by a decrease in cell death, apoptosis, and inflammatory mediators TNFα and IL-1ß. Pre-treatment with oxytocin may be useful in people who are prone to stroke.

Temporary inactivation of the infralimbic cortex impairs while the blockade of its dopamine D2 receptors enhances auditory fear extinction in rats.

Fear extinction is defined as decline in conditioned fear responses that occurs with repeated and non-reinforced exposure to a feared conditioned stimulus. Experimental evidence suggests that the extinction of fear memory requires the integration of the medial prefrontal cortex (mPFC); nevertheless, the role of its sub-regions in regulating the expression and extinction of auditory fear has been rarely addressed in literature. The present study examined the roles of the infra-limbic (IL) and pre-limbic (PL) regions of the mPFC in the expression and extinction of auditory fear by temporally deactivating these regions using lidocaine (10 µg/0.5 µl) before training male Wistar rats in auditory fear-conditioning tasks. The results showed increased freezing levels and impaired extinction through deactivating the IL rather than the PL cortex. Given the role of the dopaminergic pathways in regulating fear memory, this study also investigated the role of D2 receptors located in the IL cortex in fear extinction. Fear extinction was improved in an inverted U-shape pattern through the intra-IL infusion of 15.125, 31.25, 62.5, 125, 250 and 500 ng/0.5 µl of the D2 receptor antagonist sulpiride. In other words, the moderate doses, i.e. 31.25, 62.5, 125, 250 ng/0.5 µl, enhanced auditory fear extinction, whereas the lowest and highest doses, i.e. 15.125 and 500 ng/0.5 µl, were ineffective. These findings demonstrated the key roles of the IL cortex and its dopamine D2 receptors in regulating auditory fear in rats.

Microinjection of the BDNF receptor antagonist ANA-12 into the nucleus accumbens and medial-prefrontal cortex attenuates morphine-induced reward memory, and alterations of BDNF levels and apoptotic cells in rats.

This study was designed to examine the effects of intra- nucleus accumbens (NAc) of BDNF receptor antagonist ANA-12 on the acquisition and expression and intra- medial-prefrontal cortex (mPFC) of ANA-12 on the extinction and reinstatement of morphine-induced conditioned place preference (CPP) and also BDNF levels and apoptotic neurons in the NAc and mPFC of rats. In this study, adult male Wistar rats (200-250 g) were used. Two separate cannulas were inserted bilaterally into the NAc and/or mPFC. ANA-12 (3 µg/0.5 µl/side) was injected into the NAc and/or mPFC to evaluate the rewarding effects of morphine using a CPP paradigm. Then, the levels of BDNF and apoptotic in the NAc and mPFC were assessed at the end of each treatment phase using ELISA and TUNEL methods, respectively. All of vehicle-treated rats following morphine CPP showed the increase of BDNF levels and apoptotic neurons in the NAc and mPFC. ANA-12 significantly attenuated the acquisition and expression of morphine-induced CPP, BDNF levels and apoptotic neurons in the NAc during the acquisition, but not the expression phase. Also, ANA-12 significantly facilitated the extinction, but no effect on reinstatement of morphine CPP, and decreased BDNF levels and apoptotic neurons in the mPFC during the extinction, but not the reinstatement. We conclude that blocking TrkB with ANA-12 showed therapeutic effects on morphine-associated reward memory and neuronal death in the NAc and mPFC induced by morphine CPP. Thus, the BDNF-TrkB signaling may be important in the acquisition, expression, extinction, but not the reinstatement of morphine CPP.

Cannabidiol attenuated the maintenance and reinstatement of extinguished methylphenidate-induced conditioned place preference in rats.

Methylphenidate (MPH) is a mild CNS stimulant that has been used in hyperactive children, and patients with neurodegenerative and major depressive disorders. Exposure to MPH-associated cues enhances craving and arousal in drug users. On the other hand, cannabidiol (CBD) has antipsychotic potential that might be useful in alleviating symptoms of drug addiction. The aim of this study was to investigate the effect of CBD administration on extinction and reinstatement of MPH-induced conditioning place preference (CPP) in rats. Male rats received MPH (1, 2.5 or 5 mg/kg, i.p) or morphine (5 or 10 mg/kg, s.c.) during the conditioning phase. Following the establishment of CPP, during extinction training, 60 min prior to every CPP session, animals were given daily ICV CBD (10 or 50 µg/5 µL), vehicle alone (DMSO) 10 % or were treatment-naïve. On the reinstatement day animals after receiving the initial dose of MPH, 0.5 mg/kg, and were placed into the CPP box to evaluate the CPP scoring for 10-min. Our findings indicated that morphine (5 and 10 mg/kg; s.c.) and MPH (1 and 2.5 mg/kg; i.p.) induced a CPP. The ICV administration of both doses of CBD (10 and 50 µg/5 µL) prevented the reinstatement of MPH-induced CPP, which displayed shorter extinction latency compared to treatment-naïve or DMSO 10 % groups. Therefore, CBD's site of action is a potential target for reducing the risk of MPH relapse; however, more investigation is required.