Non-oscillatory discharges of an F-prostaglandin responsive neuron population in the olfactory bulb-telencephalon transition area in lake whitefish.
Our previous studies on olfactory bulbar responses in salmonid fishes suggest that pheromone signals might be processed by a mechanism distinct from that of other odorants. Using in vivo single-unit and electroencephalographic recordings, we investigated response characteristics of olfactory neurons in lake whitefish, Coregonus clupeaformis, a species characterized by high electrophysiological and behavioral sensitivities to the reproductive pheromone candidates F-prostaglandins. We found a neuron population responsive to F-prostaglandins in the ventromedial brain tissue strip connecting the olfactory bulb to the telencephalon. Of the 64 neurons examined in this area, 33% showed excitatory and 11% inhibitory responses to F-prostaglandins, while 52% were non-responsive to all the stimuli tested. Both phasic and tonic F-prostaglandin neuron response patterns were observed during the 10-s stimulus period; some responses were delayed from the onset of stimulation, and some persisted for a long time following stimulus cessation. This neuron population did not induce synchronized oscillatory waves upon stimulation with F-prostaglandins, despite massive discharges. We demonstrate for the first time that the olfactory bulb-telencephalon area of the brain is a distinct neural structure through which putative reproductive pheromone signals are integrated. Amino acid and F-prostaglandin neuron population discharges have different temporal characteristics, suggesting different processing mechanisms exist for odorant and pheromone signals. The observed sustained neuron discharges may play a role in amplifying pheromone signals required for triggering stereotyped neuroendocrine and/or behavior changes.
Laberge
F
F
Department of Zoology, University of Manitoba, Manitoba, Winnipeg, Canada R3T 2N2. fred_laberge@hotmail.com
Hara
T J
TJ
D000818:Animals; D001683:Biological Clocks / Q000187:drug effects* / Q000502:physiology; D005618:Fresh Water; D009434:Neural Pathways / Q000737:chemistry / Q000187:drug effects / Q000502:physiology; D009474:Neurons / Q000737:chemistry / Q000187:drug effects* / Q000502:physiology; D009830:Olfactory Bulb / Q000737:chemistry / Q000187:drug effects* / Q000502:physiology; D011461:Prostaglandins F, Synthetic / Q000032:analysis / Q000494:pharmacology*; D012487:Salmonidae; D013687:Telencephalon / Q000737:chemistry / Q000187:drug effects* / Q000502:physiology
D011461:Prostaglandins F, Synthetic