Details

Autor(en) / Beteiligte

• Puopolo, Michelino
• Bean, Bruce P
• Raviola, Elio

Titel

Spontaneous Activity of Isolated Dopaminergic Periglomerular Cells of the Main Olfactory Bulb

Ist Teil von

• Journal of neurophysiology, 2005-11, Vol.94 (5), p.3618-3627

Ort / Verlag

United States: Am Phys Soc

Erscheinungsjahr

2005

Link zum Volltext

Quelle

MEDLINE

Beschreibungen/Notizen

• Department of Neurobiology, Harvard Medical School, Boston, Massachusetts Submitted 2 March 2005; accepted in final form 15 July 2005 We examined the electrophysiological properties of a population of identified dopaminergic periglomerular cells of the main olfactory bulb using transgenic mice in which catecholaminergic neurons expressed human placental alkaline phosphatase (PLAP) on the outer surface of the plasma membrane. After acute dissociation, living dopaminergic periglomerular cells were identified by a fluorescently labeled monoclonal antibody to PLAP. In current-clamp mode, dopaminergic periglomerular cells spontaneously generated action potentials in a rhythmic fashion with an average frequency of 8 Hz. The hyperpolarization-activated cation current ( I h ) did not seem important for pacemaking because blocking the current with ZD 7288 or Cs + had little effect on spontaneous firing. To investigate what ionic currents do drive pacemaking, we performed action-potential-clamp experiments using records of pacemaking as voltage command in voltage-clamp experiments. We found that substantial TTX-sensitive Na + current flows during the interspike depolarization. In addition, substantial Ca 2+ current flowed during the interspike interval, and blocking Ca 2+ current hyperpolarized the neurons and stopped spontaneous firing. These results show that dopaminergic periglomerular cells have intrinsic pacemaking activity, supporting the possibility that they can maintain a tonic release of dopamine to modulate the sensitivity of the olfactory system during odor detection. Calcium entry into these neurons provides electrical drive for pacemaking as well as triggering transmitter release. Address for reprint requests and other correspondence: E. Raviola,Dept. of Neurobiology, Harvard Medical School, 220 Longwood Ave., Boston, MA 02115 (E-mail: elio_raviola{at}hms.harvard.edu )