Neuroscience
-
Modulation of membrane properties and excitability of retinal ganglion cells (RGCs) by dopamine was investigated in rat retinal slices, using whole cell patch clamp techniques. Application of dopamine (10 microM) caused a small depolarization of the membrane potential, a reduction of the input resistance and a decrease in the number of current-evoked action potentials of RGCs, and these effects were blocked by a D1 antagonist (SCH23390, 10 microM), but not by a D2 antagonist (sulpiride, 10 microM). SKF38393 (10 microM), a D1 agonist, but not quinpirole (10 microM), a D2 agonist, mimicked the effects of dopamine on RGCs. ⋯ SKF38393 and 8-Br-cAMP increased the amplitude of I(h), which was blocked by KT5720. The dopamine effects were abolished when the preparations were pre-incubated by ZD7288. These data strongly suggest that the dopamine effects on rat RGCs may be, at least in part, mediated by modulation of I(h) through the cAMP- and PKA-dependent pathway.
-
The intergeniculate leaflet (IGL) is a flat thalamic nucleus that responds to retinal illumination, but also to non-photic input from many brain areas. Its only known function is to modulate the circadian rhythm generated by the suprachiasmatic nucleus. Previously, the firing behavior of cells in IGL has been investigated with extra-cellular recordings, but intracellular recordings from morphologically identified mammalian IGL neurons are lacking. ⋯ This suggests that spontaneous activity was controlled by several, yet undetermined factors in addition to membrane potential. Within the IGL we found a broad range of morphologies without apparent categories and no significant correlation with activity. However, the spontaneous, usually regular, spiking and the rebound depolarization of IGL cells is typical a feature that distinguish them from neurons in ventral and from interneurons in the dorsal lateral geniculate nuclei.
-
This article has been withdrawn consistent with Elsevier Policy on Article Withdrawal (http://www.elsevier.com/locate/withdrawalpolicy). The Publisher apologizes for any inconvenience this may cause.