| First Author | Segu L | Year | 2010 |
| Journal | PLoS One | Volume | 5 |
| Issue | 3 | Pages | e9529 |
| PubMed ID | 20209108 | Mgi Jnum | J:158697 |
| Mgi Id | MGI:4439444 | Doi | 10.1371/journal.pone.0009529 |
| Citation | Segu L, et al. (2010) Hyperfunction of muscarinic receptor maintains long-term memory in 5-HT4 receptor knock-out mice. PLoS One 5(3):e9529 |
| abstractText | Patients suffering from dementia of Alzheimer's type express less serotonin 4 receptors (5-HTR(4)), but whether an absence of these receptors modifies learning and memory is unexplored. In the spatial version of the Morris water maze, we show that 5-HTR(4) knock-out (KO) and wild-type (WT) mice performed similarly for spatial learning, short- and long-term retention. Since 5-HTR(4) control mnesic abilities, we tested whether cholinergic system had circumvented the absence of 5-HTR(4). Inactivating muscarinic receptor with scopolamine, at an ineffective dose (0.8 mg/kg) to alter memory in WT mice, decreased long-term but not short-term memory of 5-HTR(4) KO mice. Other changes included decreases in the activity of choline acetyltransferase (ChAT), the required enzyme for acetylcholine synthesis, in the septum and the dorsal hippocampus in 5-HTR(4) KO under baseline conditions. Training- and scopolamine-induced increase and decrease, respectively in ChAT activity in the septum in WT mice were not detected in the 5-HTR(4) KO animals. Findings suggest that adaptive changes in cholinergic systems may circumvent the absence of 5-HTR(4) to maintain long-term memory under baseline conditions. In contrast, despite adaptive mechanisms, the absence of 5-HTR(4) aggravates scopolamine-induced memory impairments. The mechanisms whereby 5-HTR(4) mediate a tonic influence on ChAT activity and muscarinic receptors remain to be determined. |
