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Visual spatial memory is enhanced in female rats (but inhibited in males) by dietary soy phytoestrogens.

Lund TD, West TW, Tian LY, Bu LH, Simmons DL, Setchell KD, Adlercreutz H, Lephart ED - BMC Neurosci (2001)

Bottom Line: In learning and memory tasks, requiring visual spatial memory (VSM), males exhibit superior performance to females (a difference attributed to the hormonal influence of estrogen).Results suggest that dietary phytoestrogens significantly sex-reversed the normal sexually dimorphic expression of VSM.These findings suggest that dietary soy derived phytoestrogens can influence learning and memory and alter the expression of proteins involved in neural protection and inflammation in rats.

View Article: PubMed Central - HTML - PubMed

Affiliation: The Neuroscience Center Brigham Young University, Provo, Utah 84602, USA. Neuroscience@byu.edu

ABSTRACT

Background: In learning and memory tasks, requiring visual spatial memory (VSM), males exhibit superior performance to females (a difference attributed to the hormonal influence of estrogen). This study examined the influence of phytoestrogens (estrogen-like plant compounds) on VSM, utilizing radial arm-maze methods to examine varying aspects of memory. Additionally, brain phytoestrogen, calbindin (CALB), and cyclooxygenase-2 (COX-2) levels were determined.

Results: Female rats receiving lifelong exposure to a high-phytoestrogen containing diet (Phyto-600) acquired the maze faster than females fed a phytoestrogen-free diet (Phyto-free); in males the opposite diet effect was identified. In a separate experiment, at 80 days-of-age, animals fed the Phyto-600 diet lifelong either remained on the Phyto-600 or were changed to the Phyto-free diet until 120 days-of-age. Following the diet change Phyto-600 females outperformed females switched to the Phyto-free diet, while in males the opposite diet effect was identified.Furthermore, males fed the Phyto-600 diet had significantly higher phytoestrogen concentrations in a number of brain regions (frontal cortex, amygdala & cerebellum); in frontal cortex, expression of CALB (a neuroprotective calcium-binding protein) decreased while COX-2 (an inducible inflammatory factor prevalent in Alzheimer's disease) increased.

Conclusions: Results suggest that dietary phytoestrogens significantly sex-reversed the normal sexually dimorphic expression of VSM. Specifically, in tasks requiring the use of reference, but not working, memory, VSM was enhanced in females fed the Phyto-600 diet, whereas, in males VSM was inhibited by the same diet. These findings suggest that dietary soy derived phytoestrogens can influence learning and memory and alter the expression of proteins involved in neural protection and inflammation in rats.

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Dietary soy phytoestrogens influence on acquisition (shaping to criterion) of the radial arm maze. Male (a; experiment 1) and female (b; experiment 2) Long-Evans rats were fed either a phytoestrogen rich (Phyto-600) diet or a phytoestrogen free (Phyto-free) diet lifelong (from conception to adulthood). a. Number of trials (Mean + SEM; one trial per day) required for males (experiment 1) to reach a set criterion level of performance in the eight-arm radial maze. * Phyto-600 fed females reached criterion significantly earlier than Phyto-free fed females (p < 0.05) b. Number of trials (Mean + SEM; one trial per day) required for females (experiment 2) to reach a set criterion level of performance in the eight-arm radial maze. * Phyto-free fed males reached criterion significantly earlier than Phyto-600 fed males (p < 0.05)
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Figure 1: Dietary soy phytoestrogens influence on acquisition (shaping to criterion) of the radial arm maze. Male (a; experiment 1) and female (b; experiment 2) Long-Evans rats were fed either a phytoestrogen rich (Phyto-600) diet or a phytoestrogen free (Phyto-free) diet lifelong (from conception to adulthood). a. Number of trials (Mean + SEM; one trial per day) required for males (experiment 1) to reach a set criterion level of performance in the eight-arm radial maze. * Phyto-600 fed females reached criterion significantly earlier than Phyto-free fed females (p < 0.05) b. Number of trials (Mean + SEM; one trial per day) required for females (experiment 2) to reach a set criterion level of performance in the eight-arm radial maze. * Phyto-free fed males reached criterion significantly earlier than Phyto-600 fed males (p < 0.05)

Mentions: Males fed the Phyto-600 diet (lifelong) required significantly more trials (1 trial/day) to acquire the maze than males fed the Phyto-free diet (lifelong) (t(30) = 2.118, p < 0.05; see figure 1a).


Visual spatial memory is enhanced in female rats (but inhibited in males) by dietary soy phytoestrogens.

Lund TD, West TW, Tian LY, Bu LH, Simmons DL, Setchell KD, Adlercreutz H, Lephart ED - BMC Neurosci (2001)

Dietary soy phytoestrogens influence on acquisition (shaping to criterion) of the radial arm maze. Male (a; experiment 1) and female (b; experiment 2) Long-Evans rats were fed either a phytoestrogen rich (Phyto-600) diet or a phytoestrogen free (Phyto-free) diet lifelong (from conception to adulthood). a. Number of trials (Mean + SEM; one trial per day) required for males (experiment 1) to reach a set criterion level of performance in the eight-arm radial maze. * Phyto-600 fed females reached criterion significantly earlier than Phyto-free fed females (p < 0.05) b. Number of trials (Mean + SEM; one trial per day) required for females (experiment 2) to reach a set criterion level of performance in the eight-arm radial maze. * Phyto-free fed males reached criterion significantly earlier than Phyto-600 fed males (p < 0.05)
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC64558&req=5

Figure 1: Dietary soy phytoestrogens influence on acquisition (shaping to criterion) of the radial arm maze. Male (a; experiment 1) and female (b; experiment 2) Long-Evans rats were fed either a phytoestrogen rich (Phyto-600) diet or a phytoestrogen free (Phyto-free) diet lifelong (from conception to adulthood). a. Number of trials (Mean + SEM; one trial per day) required for males (experiment 1) to reach a set criterion level of performance in the eight-arm radial maze. * Phyto-600 fed females reached criterion significantly earlier than Phyto-free fed females (p < 0.05) b. Number of trials (Mean + SEM; one trial per day) required for females (experiment 2) to reach a set criterion level of performance in the eight-arm radial maze. * Phyto-free fed males reached criterion significantly earlier than Phyto-600 fed males (p < 0.05)
Mentions: Males fed the Phyto-600 diet (lifelong) required significantly more trials (1 trial/day) to acquire the maze than males fed the Phyto-free diet (lifelong) (t(30) = 2.118, p < 0.05; see figure 1a).

Bottom Line: In learning and memory tasks, requiring visual spatial memory (VSM), males exhibit superior performance to females (a difference attributed to the hormonal influence of estrogen).Results suggest that dietary phytoestrogens significantly sex-reversed the normal sexually dimorphic expression of VSM.These findings suggest that dietary soy derived phytoestrogens can influence learning and memory and alter the expression of proteins involved in neural protection and inflammation in rats.

View Article: PubMed Central - HTML - PubMed

Affiliation: The Neuroscience Center Brigham Young University, Provo, Utah 84602, USA. Neuroscience@byu.edu

ABSTRACT

Background: In learning and memory tasks, requiring visual spatial memory (VSM), males exhibit superior performance to females (a difference attributed to the hormonal influence of estrogen). This study examined the influence of phytoestrogens (estrogen-like plant compounds) on VSM, utilizing radial arm-maze methods to examine varying aspects of memory. Additionally, brain phytoestrogen, calbindin (CALB), and cyclooxygenase-2 (COX-2) levels were determined.

Results: Female rats receiving lifelong exposure to a high-phytoestrogen containing diet (Phyto-600) acquired the maze faster than females fed a phytoestrogen-free diet (Phyto-free); in males the opposite diet effect was identified. In a separate experiment, at 80 days-of-age, animals fed the Phyto-600 diet lifelong either remained on the Phyto-600 or were changed to the Phyto-free diet until 120 days-of-age. Following the diet change Phyto-600 females outperformed females switched to the Phyto-free diet, while in males the opposite diet effect was identified.Furthermore, males fed the Phyto-600 diet had significantly higher phytoestrogen concentrations in a number of brain regions (frontal cortex, amygdala & cerebellum); in frontal cortex, expression of CALB (a neuroprotective calcium-binding protein) decreased while COX-2 (an inducible inflammatory factor prevalent in Alzheimer's disease) increased.

Conclusions: Results suggest that dietary phytoestrogens significantly sex-reversed the normal sexually dimorphic expression of VSM. Specifically, in tasks requiring the use of reference, but not working, memory, VSM was enhanced in females fed the Phyto-600 diet, whereas, in males VSM was inhibited by the same diet. These findings suggest that dietary soy derived phytoestrogens can influence learning and memory and alter the expression of proteins involved in neural protection and inflammation in rats.

Show MeSH
Related in: MedlinePlus