Sex Differences in Memory Performance in the Object Recognition Test. Possible Role of Histamine Receptors

Effects of gonadectomy and hormone replacement on a spontaneous novel object recognition task in adult male rats

“…In these, although there are discrepancies regarding effects of the estrous cycle on NOR performance (Sutcliffe et al, 2007;Walf et al, 2006), evidence of superior NOR in gonadally intact female compared to male rats (Ghi et al, 1999;Sutcliffe et al, 2007) and in gonadally intact and ovariectomized female rats supplemented with estradiol compared to ovariectomized controls (Luine et al, 2003;Wallace et al, 2006) suggest that circulating estrogens positively influence the exploration and discrimination of novel objects in females. Other studies using delays of 24 hours or more also found facilitating effects of administering estradiol, progesterone and their major metabolites, and even dihydrotestosterone and other non-aromatizable testosterone metabolites immediately after the sample trial on subsequent novel object recognition in female subjects (Frye and Lacey, 2001;Gresack and Frick, 2006;Walf et al, 2006).…”

“…The novel object recognition task is in part a working memory paradigm that is sensitive to both hippocampal (Gaskin et al, 2003;Gould et al, 2002;Gulinello et al, 2006) and cortical lesions placed in and around the prefrontal areas surrounding the rhinal fissure (Aggleton et al, 1997;Barker et al, 2007;Buffalo et al, 2006;Cowell et al, 2006;Ennaceur et al, 1996;Ennaceur et al, 1997;Moses et al, 2005;Mumby and Pinel, 1994;Winters et al, 2004). It is also a task where hormone sensitivity has been previously established in findings of sex and/ or estrous cycle differences in NOR performance (Bisagno et al, 2003;Ghi et al, 1999;Sutcliffe et al, 2007;Walf et al, 2006), and in the attenuation of NOR deficits in ovariectomized female rats (with and without chronic stress) by giving ovariectomized animals estradiol (Luine et al, 2006;Luine et al, 2003;Wallace et al, 2006). Here, NOR performance was assessed for the first time in gonadectomized and hormone-replaced adult male rats.…”

H3 receptor antagonists reverse delay-dependent deficits in novel object discrimination by enhancing retrieval

“…However, the mechanism and memory processes involved in the H 3 receptor antagonist procognitive effect are still under discussion . Depending on the experimental design, thioperamide was reported to improve memory performance when administered immediately after acquisition (Orsetti et al 2001) or before the retrieval phase of the test (Ghi et al 1999).…”

Female Rats Are Smarter than Males: Influence of Test, Oestrogen Receptor Subtypes and Glutamate

“…Conversely, other research groups have demonstrated male hooded-Lister rats retain the preference for the novel object up to a 2 h inter-trial interval (King et al 2004). Gender differences within the NOR paradigm have also been confirmed in the Wistar rat, females again exhibit superior performance during longer inter-trial intervals (90 min) when compared to their male counterparts (60 min) (Ghi et al 1999). Cyclic variations in sex hormones also exert a significant impact on performance during object recognition tasks.…”