Release of neurite outgrowth promoting factors by Helisoma central ganglia depends on neural activity.
Identified buccal neurons B5 and B19 from the mollusc, Helisoma trivolvis, were plated into cell culture in order to assay for neurite outgrowth promoting factors released from central ring ganglia. The release and attachment of neurite promoting factors to the substratum of poly-lysine coated dishes could be inhibited by blocking spontaneous bioelectric activity in central ring ganglia used to condition the medium and dishes. Bioelectric activity within neurons in central ring ganglia was assayed by intracellular recording and found to be inhibited by exposure to the sodium channel blocker, tetrodotoxin (TTX; 2 x 10(-5) M), or CoCl2 (10 mM). Neither of these agents appeared to be toxic over a three day period since activity within neurons in central ring ganglia was restored following superfusion with saline. To examine the effect of blocking neural activity on the ability of central ring ganglia to release neurite outgrowth promoting factors, we compared the percentage of neurons that extended processes under 5 different conditions: (1) dishes containing conditioned medium and substrate attached growth factors (Super SAM); (2) dishes with substrate attached growth factors only and defined medium (SAM); (3) dishes containing substrate attached growth factors prepared in the presence of TTX; or (4) CoCl2; and (5) dishes containing unconditioned defined medium. The percentage of neurons extending processes under the 5 conditions were: (1) 71% (n = 32); (2) 51% (n = 33); (3) 14% (n = 37); (4) 15% (n = 47); (5) 0% (n = 40), respectively.(ABSTRACT TRUNCATED AT 250 WORDS)
Berdan
R C
RC
Department of Physiology, University of Alberta, Edmonton, Canada.
Ridgway
R L
RL
D000200:Action Potentials / Q000502:physiology; D000818:Animals; D002478:Cells, Cultured; D005724:Ganglia / Q000378:metabolism*; D009414:Nerve Growth Factors / Q000378:metabolism*; D016501:Neurites / Q000502:physiology*; D009474:Neurons / Q000502:physiology*; D012908:Snails / Q000378:metabolism*
D009414:Nerve Growth Factors