TY - JOUR
T1 - Determination of synaptic phenotype
T2 - Insulin and cAMP independently initiate development of electrotonic coupling between cultured sympathetic neurons
AU - Kessler, J. A.
AU - Spray, D. C.
AU - Saez, J. C.
AU - Bennett, M. V.L.
PY - 1984
Y1 - 1984
N2 - Electrotonic coupling between pairs of sympathetic neurons dissociated from superior cervical ganglia of neonatal rats is rare when cells are cultured for 2 weeks in a nutrient medium plus serum and is common when cells are cultured for the same period in serum-free defined medium. This defined medium is the same nutrient medium with 5 added factors (progesterone, transferrin, putrescine, insulin, and selenium). When added singly to serum-containing medium, insulin and, to a lesser extent, selenium promote the development of electrotonic and dye coupling. The insulin effect is obtained with doses as low as 0.01 μg/ml and is maximal after exposures from 3 to 5 days. The incidence of electrotonic coupling is also enhanced by exposure of cells to dibutyryl cAMP. This effect is obtained with doses as low as 0.1 mM, is faster (being maximal at ≃12 hr exposure), and is prolonged in the presence of the phosphodiesterase inhibitor caffeine. Butyrate itself promotes coupling to a small extent, but cAMP involvement is confirmed by similar effects of other membrane permeant analogues. Endogenous levels of cAMP are significantly elevated in cultures grown in the defined medium but not in those in serum-containing medium to which insulin or selenium are added. We conclude that the promotion of coupling by cAMP and by insulin or selenium are independent. The development of coupling in the defined medium thus seems to be a consequence of the addition of promoting substances (insulin, selenium) and the removal of an inhibitory effect of serum on cAMP levels.
AB - Electrotonic coupling between pairs of sympathetic neurons dissociated from superior cervical ganglia of neonatal rats is rare when cells are cultured for 2 weeks in a nutrient medium plus serum and is common when cells are cultured for the same period in serum-free defined medium. This defined medium is the same nutrient medium with 5 added factors (progesterone, transferrin, putrescine, insulin, and selenium). When added singly to serum-containing medium, insulin and, to a lesser extent, selenium promote the development of electrotonic and dye coupling. The insulin effect is obtained with doses as low as 0.01 μg/ml and is maximal after exposures from 3 to 5 days. The incidence of electrotonic coupling is also enhanced by exposure of cells to dibutyryl cAMP. This effect is obtained with doses as low as 0.1 mM, is faster (being maximal at ≃12 hr exposure), and is prolonged in the presence of the phosphodiesterase inhibitor caffeine. Butyrate itself promotes coupling to a small extent, but cAMP involvement is confirmed by similar effects of other membrane permeant analogues. Endogenous levels of cAMP are significantly elevated in cultures grown in the defined medium but not in those in serum-containing medium to which insulin or selenium are added. We conclude that the promotion of coupling by cAMP and by insulin or selenium are independent. The development of coupling in the defined medium thus seems to be a consequence of the addition of promoting substances (insulin, selenium) and the removal of an inhibitory effect of serum on cAMP levels.
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U2 - 10.1073/pnas.81.19.6235
DO - 10.1073/pnas.81.19.6235
M3 - Article
C2 - 6091144
AN - SCOPUS:0021710321
SN - 0027-8424
VL - 81
SP - 6235
EP - 6239
JO - Proceedings of the National Academy of Sciences of the United States of America
JF - Proceedings of the National Academy of Sciences of the United States of America
IS - 19 I
ER -