Dietary phytoestrogens enhance spatial memory and spine density in the hippocampus and prefrontal cortex of ovariectomized rats

2006 ◽  
Vol 1126 (1) ◽  
pp. 183-187 ◽  
Author(s):  
V. Luine ◽  
S. Attalla ◽  
G. Mohan ◽  
A. Costa ◽  
M. Frankfurt
Keyword(s):  
Prefrontal Cortex ◽  
Spatial Memory ◽  
Ovariectomized Rats ◽  
Spine Density

scholarly journals Nucleus reuniens is required for encoding and retrieving precise, hippocampal-dependent contextual fear memories in rats

2018 ◽  
Author(s):  
Karthik R. Ramanathan ◽  
Reed L. Ressler ◽  
Jingji Jin ◽  
Stephen Maren
Keyword(s):  
Prefrontal Cortex ◽  
Spatial Memory ◽  
Fear Conditioning ◽  
Medial Prefrontal Cortex ◽  
Thalamic Nucleus ◽  
Nmda Receptor Antagonist ◽  
Pavlovian Fear Conditioning ◽  
Contextual Memory ◽  
Nucleus Reuniens ◽  
Contextual Fear

AbstractThe nucleus reuniens (RE) is a ventral midline thalamic nucleus that interconnects the medial prefrontal cortex (mPFC) and hippocampus (HPC). Considerable data indicate that HPC-mPFC circuits are involved in contextual and spatial memory; however, it is not clear whether the RE mediates the acquisition or retrieval of these memories. To examine this question, we inactivated the RE with muscimol before either the acquisition or retrieval of Pavlovian fear conditioning in rats; freezing served as the index of fear. We found that RE inactivation before conditioning impaired the acquisition of contextual freezing, whereas inactivation of the RE prior to retrieval testing increased the generalization of freezing to a novel context; inactivation of the RE did not affect either the acquisition or expression of auditory fear conditioning. Interestingly, contextual conditioning impairments were absent when retrieval testing was also conducted after RE inactivation. Contextual memories acquired under RE inactivation were hippocampal-independent, insofar as contextual freezing in rats conditioned under RE inactivation was insensitive to intra-hippocampal infusions of the NMDA receptor antagonist, D,L-amino-5-phosophonovaleric acid (APV). Together, these data reveal that the RE supports hippocampal-dependent encoding of precise contextual memories that allow discrimination of dangerous from safe contexts. When the RE is inactive, however, alternate neural systems acquire an impoverished contextual memory that is only expressed when the RE is offline.SIGNIFICANCE STATEMENTThe midline thalamic nucleus reuniens (RE) coordinates communication between the hippocampus and medial prefrontal cortex, brain areas critical for contextual and spatial memory. Here we show that temporary pharmacological inactivation of RE impairs the acquisition and precision of contextual fear memories after Pavlovian fear conditioning in rats. However, inactivating the RE prior to retrieval testing restored contextual memory in rats conditioned after RE inactivation. Critically, we show that imprecise contextual memories acquired under RE inactivation are learned independently of the hippocampus. These data reveal that the RE is required for hippocampal-dependent encoding of precise contextual memories to support the discrimination of safe and dangerous contexts.

scholarly journals Synaptic plasticity in hippocampal CA1 neurons and learning behavior in acute kidney injury, and estradiol replacement in ovariectomized rats

2019 ◽  
Vol 20 (1) ◽  
Author(s):  
Fatemeh Sharifi ◽  
Parham Reisi ◽  
Maryam Malek
Keyword(s):  
Oxidative Stress ◽  
Acute Kidney Injury ◽  
Renal Failure ◽  
Synaptic Plasticity ◽  
Spatial Memory ◽  
Symptom Relief ◽  
Estrogen Therapy ◽  
Kidney Injury ◽  
Ovariectomized Rats ◽  
Positive Effects

Abstract Background Neurological complications may occur in patients with acute or chronic renal failure; however, in cases of acute renal failure, the signs and symptoms are usually more pronounced, and progressed rapidly. Oxidative stress and nitric oxide in the hippocampus, following kidney injury may be involved in cognitive impairment in patients with uremia. Although many women continue taking hormone therapy for menopausal symptom relief, but there are also some controversies about the efficacy of exogenous sex hormones, especially estrogen therapy alone, in postmenopausal women with kidney injury. Herein, to the best of our knowledge for the first time, spatial memory and synaptic plasticity at the CA1 synapse of a uremic ovariectomized rat model of menopause was characterized by estradiol replacement alone. Results While estradiol replacement in ovariectomized rats without uremia, promotes synaptic plasticity, it has an impairing effect on spatial memory through hippocampal oxidative stress under uremic conditions, with no change on synaptic plasticity. It seems that exogenous estradiol potentiated the deleterious effect of acute kidney injury (AKI) with increasing hippocampal oxidative stress. Conclusions Although, estrogen may have some positive effects on cognitive function in healthy subjects, but its efficacy in menopause subjects under uremic states such as renal transplantation, needs to be further investigated in terms of dosage and duration.

Medial prefrontal cortex oxytocin-opioid receptors interaction in spatial memory processing in rats

2019 ◽  
Vol 209 ◽  
pp. 112599 ◽  
Author(s):  
Reza Salighedar ◽  
Amir Erfanparast ◽  
Esmaeal Tamaddonfard ◽  
Farhad Soltanalinejad
Keyword(s):  
Prefrontal Cortex ◽  
Spatial Memory ◽  
Medial Prefrontal Cortex ◽  
Opioid Receptors ◽  
Memory Processing
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