Cellular activities of AOB, MOB in different behavior and brain developmental stages of mandarin voles Microtus mandarinus(In English)

摘要

Cellular activities of accessory olfactory bulbs (AOB) and main olfactory bulbs (MOB), behaviors and brain size of mandarin voles Microtus mandarinus were investigated at different postnatal developmental stages. A pup exposed to both its own familiar colony odor and a novel colony odor simultaneously spent longer time sniffing and walking cross substrate of its own colony in its postnatal days. Until postnatal days 15, 20 and 25, pups investigated their own colony substrate for significantly longer duration. Brain sizes of pups increased daily from birth, but from postnatal day 1 to 15, brain weight, cerebrum size and olfactory bulb size augmented more obviously. When pups were exposed to novel colony substrates or to their own colony substrates (control groups), the number of Fos immunopositive cells in both the mitral and granule layers of MOB, Fos-ir neurons in granule layer of AOB, numbers of activated cells in the mitral cell layer of AOB all increased significantly from postnatal days 5 to 15. But from 15 days age to 30 days age, exposure of pups to novel colony substrates caused significantly more c-fos activation than control groups in mitral and granule cell layers of MOB. Furthermore, from postnatal day 20 to 30, numbers of activated cells in the granule and mitral layers of AOB were significantly greater than those in control groups. Dense Fos-ir cells in granule layer of MOB appeared from the periphery to the core of MOB from birth to 30 days of age while dense Fos-ir cells appeared from apical to bottom region of AOB from birth. This result showed that the period from birth to about 15 days of age is a very important phase for structural development of the brain. MOB began to show obvious ability to discriminate strange and familiar odours from 15 days of age while AOB began to exhibit significant ability from 20 days of age. The results also exhibited very close relationships among behaviors, brain development and cellular activities [ A cta Zoologica Sinica 51(1):60 – 67, 2005].