Morphological analysis of synaptic plasticity in pheromonal memory
Grant-in-Aid for Scientific Research (C)
|Allocation Type||Single-year Grants|
|Research Institution||Tokyo Metropolitan Institute for Neuroscience|
ICHIKAWA Masumi Department of Anatomy and Embryology, chief of Research Staff, 解剖発生学研究部門, 主任研究員 (20124414)
|Project Period (FY)
1996 – 1997
Completed(Fiscal Year 1997)
|Budget Amount *help
¥2,400,000 (Direct Cost : ¥2,400,000)
Fiscal Year 1997 : ¥900,000 (Direct Cost : ¥900,000)
Fiscal Year 1996 : ¥1,500,000 (Direct Cost : ¥1,500,000)
|Keywords||Vomeronasal nerve / Accessory olfactory bulb / Mitral cell / Granule cell / Olfaction / Reciprocal synapse / Electron microscope|
In the present project, we studyied two analyzes od synaptic plasticity in the accessory olfactory bulb (AOB).
(1) Effect of olfactory memory formation by mating.
Female mice develop along-lasting olfactory recognition memory of a partner male by mating at the first relay in the vomeronasal system. In this study the synaptic plasticity relevant to this phenomenon was examined at reciprocal dendrodendritic synapses in the AOB of female mice by electron microscopy. The size of asymmetrical excitatory synapses (mitral/tufted to granule cells) of the reciprocal synapses was significantly larger in the group of female mice which were subjected to a treatment intended to induce olfactory mamory formation than in the control group. It is suggested that olfactory memory formation is associated with a conformational change at the level of synaptic structure of the AOB.
(2) Effect of urine stimulation.
The effects of urinary stimuli on synaptic plasticity in the AOB were studied. Adult male hamsters
were divided into four groups and each group was exposed to one of following four materials : distillled water, female hamster urine, female rat urine, and male hamster urine. After 15 days, the sizes of reciprocal synapses were examined. Exposure of adult male hamster to female hamster urine induced a reduction in the size of asymmetrical synapses, while on exposure to other kinds or urine there was no synaptic change. The sizes of the symmetrical synapses were not changed by any urinary stimulus. The present study revealed that morphological changes of synapses in the AOB were induced by urinary stimuli.
In these plastic changes, the mitral-tufted cell are induced excitable condition by long lasting urinary stimulation. On the other hand, if the animals mate with her partner, the mitral-tufted cell are induced long-lasting inhibitory condition. This long lasting inhibitory condition keep the pregnancy of female mice. these long-lasting chnages of synapses are morphological basis of memory formation. Less
Research Output (13results)