Dopamine modulation of honey bee (Apis mellifera) antennal-lobe neurons.
Primary olfactory centers [antennal lobes (ALs)] of the honey bee brain are invaded by dopamine (DA)-immunoreactive neurons early in development (pupal stage 3), immediately before a period of rapid growth and compartmentalization of the AL neuropil. Here we examine the modulatory actions of DA on honey bee AL neurons during this period. Voltage-clamp recordings in whole cell configuration were used to determine the effects of DA on ionic currents in AL neurons in vitro from pupal bees at stages 4-6 of the nine stages of metamorphic adult development. In approximately 45% of the neurons tested, DA (5-50 x 10(-5) M) reduced the amplitude of outward currents in the cells. In addition to a slowly activating, sustained outward current, DA reduced the amplitude of a rapidly activating, transient outward conductance in some cells. Both of the currents modulated by DA could be abolished by the removal of Ca2+ from the external medium or by treatment of cells with charybdotoxin (2 x 10(-8) M), a blocker of Ca2+-dependent K+ currents in the cells. Ca2+ currents were not affected by DA, nor were A-type K+ currents (I(A)). Results suggest that the delayed rectifier-like current (I(KV)) also remains intact in the presence of DA. Taken together, our data indicate that Ca2+-dependent K+ currents are targets of DA modulation in honey bee AL neurons. This study lends support to the hypothesis that DA plays a role in the developing brain of the bee.
Perk
Christopher G
CG
Department of Zoology, University of Otago, Dunedin, New Zealand.
Mercer
Alison R
AR
D000818:Animals; D000831:Animals, Newborn; D001516:Bees / Q000502:physiology*; D002118:Calcium / Q000378:metabolism*; D004298:Dopamine / Q000494:pharmacology*; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology*; D009475:Neurons, Afferent / Q000187:drug effects / Q000502:physiology*; D009830:Olfactory Bulb / Q000187:drug effects / Q000502:physiology*; D011188:Potassium / Q000378:metabolism*; D012903:Smell / Q000187:drug effects / Q000502:physiology*
D011188:Potassium; D002118:Calcium; D004298:Dopamine