Expression data of the Cerebral cortex in Tyr-Trp treated AD model mouse

Scope: As a result of population ageing, the number of Alzheimer’s disease (AD) patients has rapidly increased. There are many hypothesises on the pathogenesis of AD, but its detailed molecular mechanism is still unknown, and so no effective preventive or therapeutic measures have been established. Some reports showed a decrease in levels of norepinephrine (NE) has been suspected to be involved in the decline of cognitive function in AD patients and NE concentrations were decreased in postmortem AD patient brains. Tyr-Trp was identified as being the most effective dipeptide in enhancing norepinephrine (NE) synthesis and metabolism. And Tyr-Trp treatment ameliorated the short-term memory dysfunction in AD model mice caused by amyloid beta (Aβ) 25-35. So, the purpose of this study was to investigate the preventive or/and protective effects of Tyr-Trp administration in AD model mice. Methods and results: ddY mice were fed normal diet. After 7 days of feeding, mice were divided into 3 groups (n=10 per group) as follows: the sham group, which received saline administration and distilled water injection; the Aβ group, which received saline administration and Aβ peptides 25–35 injection; and the Aβ+YW group, which received Tyr-Trp administration and Aβ peptides 25–35 injection. Tyr-Trp was orally administered Tyr-Trp (100 mg kg-1 day-1, twice a day), starting 7 days before Aβ peptides injection. The other groups received oral administration of saline (5 mL kg-1). After Aβ peptides injection or sham operation, each groups received every oral administration. DAN microarray showed that Tyrosine hydroxylase, dopa decarboxylase and dopamine receptor D2 mRNA expressions which were downregulated in Aβ group comparing with sham group were upregulated in Aβ+YW group comparing with Aβ group. In addition, quinoid dihydropteridine reductase mRNA expression which wasn’t changed in Aβ group comparing with sham group was upregulated in Aβ+YW group comparing with Aβ group. Conclusions: These results suggest that Tyr-Trp administration might ameliorate the short-term memory dysfunction in AD model mice because of enhancing norepinephrine (NE) synthesis and metabolism through metabolism of both Tyr and Trp. Male ddY mice at 10 weeks of age (SLC, Inc., Shizuoka, Japan) were housed in a room with controlled lighting (12 h light/12 h dark), and constant temperature (25°C), and provided with moderate fat diet (Oriental Yeast Co., Ltd., Tokyo, Japan) and water ad libitum. Mice were divided into 3 groups (n=10 per group) as follows: the sham group, which received saline administration and distilled water injection; the amyloid beta (Aβ) group, which received saline administration and Aβ peptides 25–35 injection; and the Aβ+YW group, which received Tyr-Trp administration and Aβ peptides 25–35 injection. Tyr-Trp was orally administered Tyr-Trp (100 mg kg-1 day-1, twice a day), starting 7 days before Aβ peptides injection. The other groups received oral administration of saline (5 mL kg-1). After 7 days of Aβ peptides injection or sham operation, behavioral test was conducted and Cx samples were collected. DNA microarray analysis was performed on Cx samples from a total of fourteen mice (sham group: n=4, Aβgroup; n=5, Aβ+YW group; n=5) by choosing average individuals from each group on the basis of their behavioral test score.