Developing neonatal rat sympathetic and sensory neurons differ in their regulation of 5-HT3 receptor expression.
Serotonin 5-HT3 receptors (5-HT3Rs) are ligand-gated ion channels expressed by many peripheral neurons and are involved in several physiological processes. To learn more about the developmental regulation of 5-HT3R expression, we investigated rat sympathetic and vagal sensory neurons. We found that sympathetic and sensory neurons differ in their regulation of 5-HT3R expression during early postnatal life and as these neurons develop in culture. In SCG neurons 5-HT3R transcript levels are low at postnatal day 1 (P1) and increase 7.5-fold by P21; this increase occurs even after elimination of preganglionic innervation. In comparison, 5-HT3R mRNA levels in P1 nodose neurons are over 14-fold greater than in P1 SCG and change little by P21. We show that 5-HT3R transcript levels in nodose neurons depend on intact target innervation and drop by 60% after axotomy. When P1 SCG neurons develop in culture, we observed a significant increase in 5-HT3R expression: after 7 d in culture, transcript levels increase ninefold versus a threefold increase for neurons developing for 7 d in vivo. In contrast, 5-HT3R mRNA levels in cultured nodose neurons drop by 70% within 24 hr; however, this drop is transient. After 2 d, transcript levels begin to increase, and after 7 d, they are above initial values. We show that this delayed increase in 5-HT3R expression depends on neurotrophins. In both nodose and sympathetic neurons we found that the changes in 5-HT3R gene expression correlate directly with the appearance of 5-HT-evoked current densities.
Rosenberg
M
M
Department of Physiology, McGill University, Montréal, Québec, Canada H3G 1Y6.
Pié
B
B
Cooper
E
E
D000375:Aging / Q000502:physiology*; D000818:Animals; D000831:Animals, Newborn / Q000254:growth & development / Q000502:physiology*; D002478:Cells, Cultured; D004553:Electric Conductivity; D005786:Gene Expression Regulation / Q000187:drug effects; D009414:Nerve Growth Factors / Q000494:pharmacology; D009474:Neurons / Q000187:drug effects / Q000502:physiology*; D009475:Neurons, Afferent / Q000187:drug effects / Q000502:physiology*; D009620:Nodose Ganglion / Q000166:cytology / Q000502:physiology; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D011985:Receptors, Serotonin / Q000235:genetics / Q000378:metabolism*; D012701:Serotonin / Q000494:pharmacology; D017783:Superior Cervical Ganglion / Q000166:cytology / Q000502:physiology; D013564:Sympathetic Nervous System / Q000166:cytology / Q000502:physiology*
D009414:Nerve Growth Factors; D012333:RNA, Messenger; D011985:Receptors, Serotonin; D012701:Serotonin