Serotonin as a differentiation signal in early neurogenesis.
The hypothesis that serotonin (5-HT) influences the onset of differentiation (cessation of division) of prospective 5-HT target neurons during embryogenesis was tested by administering the 5-HT depleting drug p-chlorophenylalanine (pCPA) to pregnant rats and dating the time of last cell division for fetal neurons using long survival 3H-thymidine autoradiography. PCPA specifically retarded the onset of neuronal differentiation in brain regions known to contain 5-HT terminals or to have a high 5-HT content in the adult (5-HT target cells). Conversely, the 'stress' of daily vehicle injections accelerated onset of differentiation in these regions, possibly due to stimulation of 5-HT synthesis by glucocorticoids. These data support the model of 5-HT as a humoral signal for the differentiation of cells later recognized by 5-HT neurons as appropriate targets for synaptogenesis.
D000818:Animals; D001921:Brain / Q000166:cytology / Q000187:drug effects / Q000196:embryology*; D002454:Cell Differentiation / Q000187:drug effects; D005260:Female; D010134:Fenclonine / Q000494:pharmacology; D006624:Hippocampus / Q000196:embryology; D009474:Neurons / Q000166:cytology; D011247:Pregnancy; D011903:Raphe Nuclei / Q000196:embryology; D051381:Rats; D012701:Serotonin / Q000502:physiology*; D013477:Superior Colliculi / Q000196:embryology; D013787:Thalamic Nuclei / Q000196:embryology
D012701:Serotonin; D010134:Fenclonine