Architecture and physiology of insect cerebral neurosecretory cells

摘要: The architecture of neurosecretory cells (NSCs) from each two bilaterally symmetrical clusters somata in the brain moth, Manduca sexta, was determined by intracellular injection Lucifer Yellow and horseradish peroxidase. Furthermore, ionic basis action potential these examined. NSC were visualized desheathed pupal protocerebrum their reflective opalescence under direct fiberoptic illumination. Intracellular staining revealed at least six morphological classes monopolar neurons distinguishable size position as well patterns dendritic fields, axonal pathways, terminal projections. number NSCs is accord with estimated neurohormones--a finding that suggests a different neuroendocrine function for class. observed overlap fields consistent synaptic interaction among or sharing common inputs. Finally, demonstration ramifications varicosities corpora cardiaca allata confirms are neurohemal organs cerebral NSCs. recordings had resting membrane potentials 35 to 45 mV electrically excitable; they showed broad (10 20 msec) overshooting potentials, long hyperpolarizing afterpotentials, postsynaptic potentials. Impulse amplitude maintained absence external sodium presence 10(-5)M tetrodotoxin, but impulses completely reversibly blocked 10 mM cobalt. Postsynaptic all three conditions. These results indicate generated primarily calcium inward currents. Cations, peroxidase bathing medium did not readily exchange extracellular space brain. However, light protease treatment facilitated ion exchange. findings provide evidence persistence blood-brain barrier even ganglia.