Intra-perirhinal cortex administration of estradiol, but not an ERβ agonist, modulates object-recognition memory in ovariectomized rats

Rapid actions of oestrogens and their receptors on memory acquisition and consolidation in females

“…These presynaptic actions of ERβ may be more effective at enhancing late memory consolidation, whereas rapid ER postsynaptic actions may enhance both early and later stages of memory consolidation. L‐LTP and later stages of memory consolidation require gene transcription and protein synthesis, and this agrees with findings that post‐acquisition oestrogenic treatments that produce enhanced memory several hours later are mediated by epigenetic regulation of transcription of memory enhancing genes . Pre‐acquisition treatments that affect performance before the closure of the consolidation window instead may only be mediated by effects upon early stages of memory encoding/consolidation, when E‐LTP and memories are still independent of gene transcription .…”

“…L-LTP and later stages of memory consolidation require gene transcription and protein synthesis, 17,18 and this agrees with findings that post-acquisition oestrogenic treatments that produce enhanced memory several hours later are mediated by epigenetic regulation of transcription of memory enhancing genes. [83][84][85][86][87][88][89][90][91][92][93][94][95][96][97] Pre-acquisition treatments that affect performance before the closure of the consolidation window instead may only be mediated by effects upon early stages of memory encoding/ consolidation, when E-LTP and memories are still independent of gene transcription. 18 Although speculative at this point, this idea is worth pursuing in further research.…”

“…Temporal lobe cortices may also be a key player because immediate post‐training infusion of 17β‐oestradiol into the perirhinal cortex/entorhinal cortex enhances object recognition in ovariectomised rats using a task similar to those described above. However, using a delayed nonmatching‐to‐sample task of object recognition, the same investigators found that perirhinal/entorhinal infusion of 17β‐oestradiol impairs object recognition, suggesting potential task‐specific or brain region‐specific effects of 17β‐oestradiol on memory consolidation. These few studies indicate the potential key involvement of nonhippocampal brain regions in the memory‐enhancing effects of oestradiol that should be revealed by future investigations.…”

Assessing object-recognition memory in rats: Pitfalls of the existent tasks and the advantages of a new test

“…Variants of the NOP test are the most widely used, by far. Concerns have been raised, however, about the internal validity of the NOP test as a method of measuring object-recognition abilities (Gaskin et al, 2010;Gervais, Brake, & Mumby, 2013;Gervais, Hamel, Brake, & Mumby, 2016); these concerns are outlined, below. Although DNMS tasks have not been subjected to the same criticisms, they possess different shortcomings that limit their usefulness; namely, compared to the NOP test, conventional DNMS tasks are considerably more difficult and time-consuming to employ.…”

“…Despite the practical advantages of the NOP test, however, some recent observations have raised concerns about the internal validity of the NOP test as a gauge for objectrecognition abilities. For instance, the amount of time rats spend investigating objects during the familiarization phase does not predict the magnitude of their novel-object preference, nor does providing rats with prolonged or repeated exposure to a sample object affect preference magnitude (Gaskin et al, 2010;Gervais et al, 2013Gervais et al, , 2016. These findings are contrary to two major assumptions that underlie the manner in which NOP data are usually interpreted: (1) that rats are encoding information about the sample object's features when investigating it during the familiarization phase, and (2) the magnitude of the novel-object preference is a reflection of the persistence or accuracy of a rat's memory for the sample object.…”