[Abstract Title]. - Society for Neuroscience

projection neurons. The large size and the accessibility of the DGNs in crayfish and lobsters have
made them ideal subjects for studies of their anatomy, physiology and development. Of
particular interest, however, is their proximity to the only two populations of interneurons in the
crustacean midbrain where cell proliferation occurs throughout the life of the animal. These local
interneurons in Cluster 9 and projection neurons in Cluster 10, arborize in the same neuropils as
the DGN, and their proliferation zones are adjacent to the AL. In addition a recently discovered
vascular neurogenic niche in the brains of crayfish and lobsters lies on the surface of the AL. The
migratory streams that link the niche to the proliferation zones of Cluster 9 and 10 also lie across
the surface of the AL. Electrical stimulation of the surface of the OL or AL (cortex) results in a
hyperpolarization of the DGN. Stimulation of the projection neurons (Cluster 10), the OGT or
the AL medulla, depolarizes the DGN. In these studies, unilateral stimulation of a DGN in semiisolated
brains was carried out over a period of 6 hours while perfusing with 0.5mg/ml
bromodeoxyuridine (BrdU) in saline. We find that the number of labeled cells on the stimulated
side is increased compared with the unstimulated side if the DGN is depolarized to its spiking
threshold, but not if it is hyperpolarized. Counts of Cluster 10 cell proliferation, and HPLC
measurements of the serotonin content of the ALs in unstimulated animals, reveal a high degree
of symmetry between left and right side measurements. We conclude that stimulation of the
DGN releases serotonin into the blood capillary system of the Al and cell clusters 9 and 10,
where it acts to increase the rate of cell proliferation. This neuron therefore constitutes a neural
pathway that regulates adult neurogenesis.
Disclosures: D.C. Sandeman, None; A.M. Rose, None; J.L. Benton, None; B.S. Beltz, None.
Poster
229. Neuronal and Glial Proliferation III
Time: Sunday, November 16, 2008, 1:00 pm - 5:00 pm
Program#/Poster#: 229.18/A18
Topic: A.02.a. Proliferation
Title: Induction of long-term depression suppresses hippocampal adult neurogenesis enhanced
by long-term potentiation in the rat
Authors: *S. CHUN 1,2 , M. JUNG 2 , W. SUN 1 ;
1 Dept. of Anat., Korea Univ., Seoul, Republic of Korea; 2 Neurosci. Lab., Ajou Univ. Sch. of
Med., Suwon, Republic of Korea
Abstract: Neurogenesis persists in certain adult brain regions including hippocampal dentate
gyrus (DG). Recently we have shown that LTP induction in the afferent pathway enhances adult
neurogenesis in the DG. The effect of LTD induction on hippocampal adult neurogenesis is