No effect of glucose administration in a novel contextual fear generalization protocol in rats

Abstract

The excessive transfer of fear acquired for one particular context to similar situations has been implicated in the development and maintenance of anxiety disorders, such as post-traumatic stress disorder. Recent evidence suggests that glucose ingestion improves the retention of context conditioning. It has been speculated that glucose might exert that effect by ameliorating hippocampal functioning, and may hold promise as a therapeutic add-on in traumatized patients because improved retention of contextual fear could help to restrict its generalization. However, direct data regarding the effect of glucose on contextual generalization are lacking. Here, we introduce a new behavioral protocol to study such contextual fear generalization in rats. In adult Wistar rats, our procedure yields a gradient of generalization, with progressively less freezing when going from the original training context, over a perceptually similar generalization context, to a markedly dissimilar context. Moreover, we find a flattening of the gradient when the training-test interval is prolonged with 1 week. We next examine the effect of systemic glucose administration on contextual generalization with this novel procedure. Our data do not sustain generalization-reducing effects of glucose and question its applicability in traumatic situations. In summary, we have developed a replicable contextual generalization procedure for rats and demonstrate how it is a valuable tool to examine the neurobiological correlates and test pharmacological interventions pertaining to an important mechanism in the etiology of pathological anxiety.

Forebrain-specific, conditional silencing of Staufen2 alters synaptic plasticity, learning, and memory in rats

“…4d ), indicating that the animals recognized commonalities of both contexts (i.e. the shock grid) and associated them with the aversive experience [ 36 ]. Stau2 KD rats, however, displayed a significantly reduced step-down latency in the testing chamber “B” compared to the conditioning “A” (Fig.…”

Rats remember: Lack of drug-induced post-retrieval amnesia for auditory fear memories

“…Mean freezing levels during the Reactivation CS, Test STM (average of CS1-3) and Test 1 (average of CS1-3) were overall similar, but somewhat higher in our hands (Experiment S7, Duvarci 2005 protocol: 56%, 75% and 71%, respectively) than in the control animals of prior publications (Nader et al 2000: 66%, 54% and 56%, Duvarci et al 2005: 43%, 44% and 44%, respectively, values obtained from graphs). Such generally higher freezing levels in unoperated animals are not uncommon, although it is not clear whether they reflect differences in fear or differences in freezing tendencies (Luyten et al 2016; Zhang et al 2001). Regardless, our data do indicate clear retrieval of the fear memory, no extinction resulting from the short-term memory test and sufficient room to observe amnesia in Experiment 7.…”

A preregistered, direct replication attempt of the retrieval-extinction effect in cued fear conditioning in rats

“…Animals were trained and tested in squads of four, in four identical fear conditioning chambers, located in sound-attenuating cubicles (Contextual NIR Video Fear Conditioning System for Rats, Med Associates Inc., St. Albans, VT, USA). Contextual features could be changed in between sessions to create two distinct contexts (Luyten et al 2016). Context A consisted of a standard chamber, with a standard grid floor, a black triangular insert, illuminated by infrared and white light, and was cleaned and scented with a household cleaning product.…”