Agonist-mediated regulation of presynaptic receptor function during development of rat septal neurons in culture.
Presynaptic receptors modulating the release of acetylcholine (ACh) were studied in fetal septal neurons cultured in a growth medium to which various drugs were added from day 3 in vitro (DIV 3) to DIV 14. The influence of these drugs on the function of the presynaptic muscarinic (M-) autoreceptor was determined at DIV 14 by measuring the inhibitory effect of the M-agonist oxotremorine on the electrically-evoked release of [(3)H]ACh from cultures pre-incubated with [(3)H]choline. The presence of the M-agonists oxotremorine (100 micromol/L) or carbachol (100 micromol/L) from DIV 3 to DIV 14, or from DIV 13 to DIV 14, abolished M-autoreceptor function at DIV 14, whereas the presence of the M-antagonist atropine (10 micromol/L from DIV 3 to DIV 14) during growth left M-autoreceptor function unaltered. Inhibition of ACh esterase by donepezil (1 micromol/L from DIV 3 to DIV 14) weakly decreased M-autoreceptor function at DIV 14; inhibition of neuronal firing by 0.1 tetrodotoxin (0.1 micromol/L from DIV 3 to DIV 14) did not tend to affect M-autoreceptor function at DIV 14. Co-cultivation of fetal septal and raphe neurons for 2 weeks yielded cell cultures containing both vesicular ACh transporter- and tryptophan hydroxylase-immunopositive cells. From these cultures, the release of both [(3)H]ACh and [(3)H]5-HT could be induced by electrical field stimulation. In co-cultured neurons versus septal-only ones the inhibitory effect of oxotremorine on the evoked release of [(3)H]ACh appeared almost normal, whereas that of the selective 5-HT(1B) agonist 3-(1,2,5,6-tetrahydropyrid-4-yl)pyrrollo[3,2-b]pyrid-5-one (CP-93,129) was completely abolished. The effects of CP-93,129 were also absent on DIV 14 in septal mono-cultures grown in the presence of CP-93,129 (10 micromol/L) from DIV 3 to DIV 14. It is therefore concluded that the regulation of presynaptic receptor function strongly depends on the concentrations of endogenous transmitters in the neuronal environment.
Ehret
Andreas
A
Laboratory of Neuropharmacology, Institute for Experimental and Clinical Pharmacology and Toxicology, University of Freiburg, Hansastrasse, Freiburg, Germany.
Birthelmer
Anja
A
Rutz
Susanne
S
Riegert
Céline
C
Rothmaier
Anna Katharina
AK
Jackisch
Rolf
R
D000109:Acetylcholine / Q000378:metabolism; D000818:Animals; D002478:Cells, Cultured; D018920:Coculture Techniques; D004305:Dose-Response Relationship, Drug; D004558:Electric Stimulation / Q000379:methods; D004622:Embryo, Mammalian; D018507:Gene Expression Regulation, Developmental / Q000187:drug effects / Q000502:physiology; D018721:Muscarinic Agonists / Q000494:pharmacology*; D009474:Neurons / Q000145:classification / Q000166:cytology* / Q000187:drug effects; D010095:Oxotremorine / Q000494:pharmacology*; D011725:Pyridines / Q000494:pharmacology; D011758:Pyrroles / Q000494:pharmacology; D051381:Rats; D011976:Receptors, Muscarinic / Q000378:metabolism*; D017661:Receptors, Presynaptic / Q000187:drug effects*; D020665:Septum of Brain / Q000166:cytology*; D012701:Serotonin / Q000378:metabolism; D017366:Serotonin Receptor Agonists / Q000494:pharmacology; D013997:Time Factors; D014316:Tritium / Q000378:metabolism; D014365:Tryptophan Hydroxylase / Q000378:metabolism; D050494:Vesicular Acetylcholine Transport Proteins / Q000378:metabolism
D018721:Muscarinic Agonists; D011725:Pyridines; D011758:Pyrroles; D011976:Receptors, Muscarinic; D017661:Receptors, Presynaptic; D017366:Serotonin Receptor Agonists; D050494:Vesicular Acetylcholine Transport Proteins; D014316:Tritium; C065046:3-(1,2,5,6-tetrahydropyrid-4-yl)pyrrolo(3,2-b)pyrid-5-one; D012701:Serotonin; D010095:Oxotremorine; D014365:Tryptophan Hydroxylase; D000109:Acetylcholine