Neuroscience
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Tamoxifen (TAM), a selective estrogen receptor modulator, has frequently been used in the treatment of breast cancer. In view of the fact that cognitive deficits in women who receive adjuvant chemotherapy for breast cancer is a common health problem, using female animal models for investigating the cognitive effects of TAM administration may improve our knowledge of TAM therapy. Therefore, the present study assessed the role of dorsal hippocampal cholinergic nicotinic receptors (nAChRs) in the effect of TAM administration on memory retrieval in ovariectomized (OVX) and non-OVX female rats using a passive avoidance learning task. ⋯ Moreover, the administration of an ineffective dose of TAM (2mg/kg) had no effect on memory retrieval in OVX rats, while pre-test intra-CA1 microinjection of mecamylamine (0.3μg/rat) impaired memory retrieval. Taken together, it can be concluded that the impairing effect of TAM on memory formation may be modulated by nAChRs of the CA1 regions. It seems that memory impairment may be considered as an important side effect of TAM.
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Temporal lobe epilepsy (TLE) is the most common type of epilepsy in humans. The lithium-pilocarpine model in rodents reproduces some of the main features of human TLE. Three-week-old Wistar rats were used in this study. ⋯ The antagonist had no effects on EPSC amplitude in slices from control animals. Thus, our data demonstrate that PILO-induced SE affects subunit composition of AMPARs in different brain areas, including the mPFC. SE induces transient (up to few days) incorporation of CP-AMPARs in the excitatory synapses of mPFC pyramidal neurons, which may disrupt normal circuitry functions.
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Regret and relief are associated with counterfactual thinking and are sensitive to various social contexts. In the present fMRI study, we investigated the neural basis for regret and relief and how social context (following vs. not following advice) modulates them by employing a sequential risk-taking task. Participants were asked to open a series of boxes consecutively until they decided to stop. ⋯ At the neural level, striatum, vmPFC/mOFC, and vACC activations were associated with greater relief. Meanwhile, dmPFC and left superior temporal gyrus were associated with greater regret. Additionally, dACC showed stronger activation in the Not-Follow context than the Follow context.
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The arcuate nucleus (ARC) plays an important role in the hypothalamic control of energy homeostasis. Expression of various purinoceptor subtypes in the rat ARC and physiological studies suggest a modulatory function of P2 receptors within the neuroglial ARC circuitry. A differentiated mixed neuronal and glial microculture was therefore established from postnatal rat ARC, revealing neuronal expression of ARC-specific transmitters involved in food intake regulation (neuropeptide Y (NPY), proopiomelanocortin (POMC), tyrosine hydroxylase (TH)). ⋯ Agonist-mediated intracellular calcium signals were suppressed in all LDD neurons but only 25% of astrocytes in the absence of extracellular calcium, suggestive of metabotropic P2Y receptor expression in the majority of ARC astrocytes. The highly P2Y1-selective receptor agonists MRS2365 and 2-methylthioadenosine-5'diphosphate (2-MeSADP) activated 75-85% of all 2-MeSATP-responsive ARC astrocytes. Taking into consideration the high potency to dose-dependently stimulate ARC cells of the LDD group, the high affinity for rat P2X(1-3) and low affinity for rat P2X4, P2X7 and P2Y receptor subtypes except P2Y1 and P2Y13, the agonist 2-MeSATP primarily acted upon P2X2 and P2Y1 purinoceptors to trigger intracellular calcium signaling in ARC neurons and astrocytes.
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Previous neuroimaging studies provide evidence for the involvement of the anterior insulae (INSs) in perceptual decision-making processes. However, how the insular cortex is involved in integration of degraded sensory information to create a conscious percept of environment and to drive our behaviors still remains a mystery. In this study, using functional magnetic resonance imaging (fMRI) and four different perceptual categorization tasks in visual and audio-visual domains, we measured blood oxygen level dependent (BOLD) signals and examined the roles of INSs in easy and difficult perceptual decision-making. ⋯ We hypothesized that significantly higher BOLD response would be associated with the ambiguity of the sensory information and decision-making difficulty. In all of our experimental tasks, we found the INS activity consistently increased with task difficulty and participants' behavioral performance changed with the ambiguity of the presented sensory information. These findings support the hypothesis that the anterior insulae are involved in sensory-guided, goal-directed behaviors and their activities can predict perceptual load and task difficulty.