Role of olfactory bulb serotonin in olfactory learning in the greater short-nosed fruit bat, Cynopterus sphinx (Chiroptera: Pteropodidae).
The role of olfactory bulb (OB) serotonin [5-hydroxytryptamine (5-HT)] in olfactory learning and memory was tested in the greater short-nosed fruit bat, Cynopterus sphinx (family Pteropodidae). Graded concentrations (25, 40, and 60microg) of 5,7-dihydroxytryptamine (5,7-DHT) or saline were injected into the OB of bats one day before training to the novel odor. In a behavioral test, 5,7-DHT (60microg) injected bats made significantly fewer feeding attempts and bouts when compared to saline-injected bats during learning and in the memory test. Subsequent biochemical analysis showed that 5-HT level was effectively depleted in the OB of 5,7-DHT injected bats. To test odor-induced 5-HT mediated changes in 5-HT receptors and second messenger cascade in the OB, we examined the expression of 5-HT receptors and mitogen-activated protein kinase (MAPK)/Erk cascade after training to the novel odor. We found that odor stimulation up-regulated the expression of 5-HT(1A) receptor, Erk1 and Creb1 mRNA, and phosphorylation of ERK1 and CREB1. Odor stimulation failed to induce expression in 5-HT-depleted bats, which is similar to control bats and significantly low compared to saline-treated bats. Together these data revealed that the level of 5-HT in the OB may regulate olfactory learning and memory in C. sphinx through Erk and CREB.
Ganesh
Ambigapathy
A
Department of Animal Science, School of Life Sciences, Bharathidasan University, Tiruchirappalli, India.
Bogdanowicz
Wieslaw
W
Haupt
Moritz
M
Marimuthu
Ganapathy
G
Rajan
Koilmani Emmanuvel
KE
D015116:5,7-Dihydroxytryptamine / Q000494:pharmacology; D000818:Animals; D002685:Chiroptera / Q000502:physiology*; D017362:Cyclic AMP Response Element-Binding Protein / Q000235:genetics / Q000502:physiology; D005247:Feeding Behavior; D007858:Learning / Q000502:physiology; D008568:Memory / Q000502:physiology; D018377:Neurotransmitter Agents / Q000502:physiology; D009638:Norepinephrine / Q000502:physiology; D009812:Odorants; D009830:Olfactory Bulb / Q000187:drug effects / Q000502:physiology*; D012333:RNA, Messenger / Q000235:genetics; D044282:Receptor, Serotonin, 5-HT1A / Q000235:genetics / Q000502:physiology; D012701:Serotonin / Q000172:deficiency / Q000502:physiology*; D012903:Smell / Q000502:physiology*
D017362:Cyclic AMP Response Element-Binding Protein; D018377:Neurotransmitter Agents; D012333:RNA, Messenger; D044282:Receptor, Serotonin, 5-HT1A; D015116:5,7-Dihydroxytryptamine; D012701:Serotonin; D009638:Norepinephrine