Acute sleep-promoting action of the melatonin agonist, ramelteon, in the rat.

Insomnia, which is severe enough to warrant treatment, occurs in approximately 10% of the general population. It is associated with a range of adverse consequences for human health, economic productivity and quality of life. In animal and human studies, administration of melatonin has been reported to promote sleep, although there has been controversy regarding its effectiveness.

Modulation by group 1 metabotropic glutamate receptors of depotentiation in the dentate gyrus of freely moving rats.

In the hippocampus, synaptic depression of potentiated synapses in the form of depotentiation, or of naive synapses in the form of long-term depression (LTD) is mediated by distinct molecular mechanisms. Activation of group 1 metabotropic glutamate receptors (mGluRs) is critically required for both hippocampal long-term potentiation (LTP) and LTD in vivo, but their involvement in depotentiation is unclear. In this study, we investigated whether this class of mGluRs contributes to depotentiation in freely moving rats.

Regulation of depotentiation and long-term potentiation in the dentate gyrus of freely moving rats by dopamine D2-like receptors.

Dopamine receptors are significantly involved in hippocampus-based cognitive processes. Whereas the involvement of D1-like receptors in hippocampal plasticity has been described, the role of D2-like receptors remains to be clarified. Therefore, we investigated the contribution of D2-like receptors to synaptic transmission, long-term potentiation (LTP) and depotentiation in the dentate gyrus of freely moving rats.

Modulation by serotonin 5-HT(4) receptors of long-term potentiation and depotentiation in the dentate gyrus of freely moving rats.

Tetanization-induced long-term potentiation (LTP) in the hippocampus can be depotentiated by low-frequency stimulation. 5-HT(4) receptors are expressed in the hippocampus and are suggested to be involved in hippocampus-dependent cognitive processes. Since the role of these receptors in the dentate gyrus has yet not been characterized, this study investigated the effects of 5-HT(4) receptors on basal synaptic transmission, LTP and depotentiation in the dentate gyrus of freely moving rats.