title: Age- and location-dependent differences in store depletion-induced h-channel plasticity in hippocampal pyramidal neurons.
abstract: Disruptions of endoplasmic reticulum (ER) Ca(2+) homeostasis are heavily linked to neuronal pathology. Depletion of ER Ca(2+) stores can result in cellular dysfunction and potentially cell death, although adaptive processes exist to aid in survival. We examined the age and region dependence of one postulated, adaptive response to ER store-depletion (SD), hyperpolarization-activated cation-nonspecific (h)-channel plasticity in neurons of the dorsal and ventral hippocampus (DHC and VHC, respectively) from adolescent and adult rats. With the use of whole-cell patch-clamp recordings from the soma and dendrites of CA1 pyramidal neurons, we observed a change in h-sensitive measurements in response to SD, induced by treatment with cyclopiazonic acid, a sarcoplasmic reticulum/ER Ca(2+)-ATPase blocker. We found that whereas DHC and VHC neurons in adolescent animals respond to SD with a perisomatic expression of SD h plasticity, adult animals express SD h plasticity with a dendritic and somatodendritic locus of plasticity in DHC and VHC neurons, respectively. Furthermore, SD h plasticity in adults was dependent on membrane potential and on the activation of L-type voltage-gated Ca(2+) channels. These results suggest that cellular responses to the impairment of ER function, or ER stress, are dependent on brain region and age and that the differential expression of SD h plasticity could provide a neural basis for region- and age-dependent disease vulnerabilities.
authors.affiliation: The Institute for Neuroscience and Center for Learning and Memory, The University of Texas at Austin, Austin, Texas; and.
authors.forename: Ann M
authors.initials: AM
authors.lastname: Clemens
authors.forename: Daniel
authors.initials: D
authors.lastname: Johnston
mesh_terms: D000200:Action Potentials; D000367:Age Factors; D000818:Animals; D056547:CA1 Region, Hippocampal / Q000166:cytology / Q000254:growth & development / Q000502:physiology*; D020746:Calcium Channels, L-Type / Q000378:metabolism; D020013:Calcium Signaling; D004721:Endoplasmic Reticulum / Q000378:metabolism; D064428:Hyperpolarization-Activated Cyclic Nucleotide-Gated Channels / Q000378:metabolism*; D007211:Indoles / Q000494:pharmacology; D008297:Male; D008564:Membrane Potentials; D009473:Neuronal Plasticity; D009928:Organ Specificity; D017966:Pyramidal Cells / Q000378:metabolism / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D053498:Sarcoplasmic Reticulum Calcium-Transporting ATPases / Q000037:antagonists & inhibitors / Q000378:metabolism
chemical_list: D020746:Calcium Channels, L-Type; D064428:Hyperpolarization-Activated Cyclic Nucleotide-Gated Channels; D007211:Indoles; D053498:Sarcoplasmic Reticulum Calcium-Transporting ATPases; C000543:cyclopiazonic acid
keywords: calcium stores; h channel; hippocampus; plasticity