title: Nicotine-Mediated ADP to Spike Transition: Double Spiking in Septal Neurons.
abstract: The majority of neurons in lateral septum (LS) are electrically silent at resting membrane potential. Nicotine transiently excites a subset of neurons and occasionally leads to long lasting bursting activity upon longer applications. We have observed simultaneous changes in frequencies and amplitudes of spontaneous action potentials (AP) in the presence of nicotine. During the prolonged exposure, nicotine increased numbers of spikes within a burst. One of the hallmarks of nicotine effects was the occurrences of double spikes (known also as bursting). Alignment of 51 spontaneous spikes, triggered upon continuous application of nicotine, revealed that the slope of after-depolarizing potential gradually increased (1.4 vs. 3 mV/ms) and neuron fired the second AP, termed as double spiking. A transition from a single AP to double spikes increased the amplitude of after-hyperpolarizing potential. The amplitude of the second (premature) AP was smaller compared to the first one, and this correlation persisted in regard to their duration (half-width). A similar bursting activity in the presence of nicotine, to our knowledge, has not been reported previously in the septal structure in general and in LS in particular.
authors.affiliation: Department of Biological Sciences, Center for Biomedical Studies, University of Texas at Brownsville, Brownsville, TX, 78520, USA. skodirov@msm.edu.|Neuroscience Institute, Morehouse School of Medicine, 720 Westview Drive SW, Atlanta, GA, 30310, USA. skodirov@msm.edu.
authors.forename: Sodikdjon A
authors.initials: SA
authors.lastname: Kodirov
authors.affiliation: Johannes Gutenberg University, 55099, Mainz, Germany.|Heidelberg University, Heidelberg, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Wehrmeister
authors.affiliation: Department of Biological Sciences, Center for Biomedical Studies, University of Texas at Brownsville, Brownsville, TX, 78520, USA.
authors.forename: Luis
authors.initials: L
authors.lastname: Colom
mesh_terms: D000200:Action Potentials / Q000187:drug effects / Q000502:physiology*; D000244:Adenosine Diphosphate / Q000378:metabolism*; D000818:Animals; D055724:Electrophysiological Phenomena; D009474:Neurons / Q000502:physiology*; D009538:Nicotine / Q000378:metabolism* / Q000494:pharmacology; D018408:Patch-Clamp Techniques; D051381:Rats; D020665:Septum of Brain / Q000166:cytology / Q000378:metabolism
chemical_list: D000244:Adenosine Diphosphate; D009538:Nicotine
keywords: ADP; AHP; Action potentials; Double spikes; HCN channels; Lateral septum