Ovarian Hormones and Cognition in the Aged Female Rat: I. Long-Term, but Not Short-Term, Ovariectomy Enhances Spatial Performance.

[Correction Notice: An erratum for this article was reported in Vol 118(2) of Behavioral Neuroscience (see record 2007-16850-001). The fifth sentence of the abstract reads, "Aged rats exhibited estradiol and elevated progesterone levels comparable to those of young rats." The sentence should read as follows: "Aged rats exhibited similar estradiol and elevated progesterone levels compared with those of young rats."] Although research suggests that ovariectomy (ovx) is detrimental to spatial cognition in young rats, little work has evaluated the cognitive effects of ovx in aged rats. The authors investigated the effects of ovx in aged rats using the water radial-arm maze. In Study 1, young rats and aged rats receiving ovx 1.5 months before testing outperformed aged rats receiving sham surgery or ovx 21 days before testing. In Study 2, young rats and aged rats receiving ovx 2.0 or 6.0 months before testing outperformed aged sham rats. Aged rats exhibited estradiol and elevated progesterone levels comparable to those of young rats. The findings suggest that 1.5-6.0 months, but not 21 days, of ovx improves spatial memory in aged rats. The hypothesis that long-term ovarian hormone loss is detrimental to spatial memory in aged rats was not supported. The authors hypothesize that removal of elevated progesterone levels is related to the ovx-induced cognitive enhancement. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Peripheral delivery of a ROCK inhibitor improves learning and working memory.

Previously, utilizing a series of genome-wide association, brain imaging, and gene expression studies we implicated the KIBRA gene and the RhoA/ROCK pathway in hippocampal-mediated human memory. Here we show that peripheral administration of the ROCK inhibitor hydroxyfasudil improves spatial learning and working memory in the rodent model. This study supports the action of ROCK on learning and memory, suggests the potential value of ROCK inhibition for the promotion of cognition in humans, and highlights the powerful potential of unbiased genome-wide association studies to inform potential novel uses for existing pharmaceuticals. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Ovarian Hormones and Cognition in the Aged Female Rat: II. Progesterone Supplementation Reverses the Cognitive Enhancing Effects of Ovariectomy.

The authors hypothesized that the progesterone component of some hormone replacement therapies in women is detrimental to cognition. A previous study showed that ovariectomy (ovx) in aged rats enhanced spatial working memory and decreased elevated progesterone levels (H. A. Bimonte-Nelson, R. S. Singleton, C. L. Hunter, et al., 2003). The current study evaluated whether progesterone administration counteracts these cognitive enhancing effects of ovx. Aged sham and aged ovx rats given progesterone exhibited compromised learning of the working and reference memory components of the task, and made more working memory errors on the latter testing days compared with aged ovx rats not given progesterone. Results suggest that whereas ovx of the aged female rat enhances learning and the ability to handle numerous items of spatial working memory information, progesterone is detrimental to these aspects of performance. These findings may speak to studies in menopausal women which suggest that combination hormone therapies have a negative impact on cognition. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

"Ovarian hormones and cognition in the aged female rat: I. Long-term, but not short-term, ovariectomy enhances spatial performance": Correction to Bimonte-Nelson et al. (2003).

Reports an error in "Ovarian Hormones and Cognition in the Aged Female Rat: I. Long-Term, but Not Short-Term, Ovariectomy Enhances Spatial Performance" by Heather A. Bimonte-Nelson, Rachel S. Singleton, Christopher L. Hunter, Kimber L. Price, Alfred B. Moore and Ann-Charlotte E. Granholm (Behavioral Neuroscience, 2003[Dec], Vol 117[6], 1395-1406). The fifth sentence of the abstract reads, "Aged rats exhibited estradiol and elevated progesterone levels comparable to those of young rats." The sentence should read as follows: "Aged rats exhibited similar estradiol and elevated progesterone levels compared with those of young rats." (The following abstract of the original article appeared in record 2003-10460-025.) Although research suggests that ovariectomy (ovx) is detrimental to spatial cognition in young rats, little work has evaluated the cognitive effects of ovx in aged rats. The authors investigated the effects of ovx in aged rats using the water radial-arm maze. In Study 1, young rats and aged rats receiving ovx 1.5 months before testing outperformed aged rats receiving sham surgery or ovx 21 days before testing. In Study 2, young rats and aged rats receiving ovx 2.0 or 6.0 months before testing outperformed aged sham rats. Aged rats exhibited estradiol and elevated progesterone levels comparable to those of young rats. The findings suggest that 1.5-6.0 months, but not 21 days, of ovx improves spatial memory in aged rats. The hypothesis that long-term ovarian hormone loss is detrimental to spatial memory in aged rats was not supported. The authors hypothesize that removal of elevated progesterone levels is related to the ovx-induced cognitive enhancement. (PsycINFO Database Record (c) 2010 APA, all rights reserved)