Effects of cutting the olfactory peduncle on migration of subventricular zone cells in adult rats

Deguang WANG; Fengzhen ZHANG

ABSTRACT

BACKGROUND:

There are neuronal precursors in subventricular zone (SVZ) of adult rat. The precursors migrate to olfactory bulb along the rostral migratory stream (RMS) and differentiate into local interneurons of olfactory bulb. But whether cutting the RMS would affect the migration of subventricular precursors is unknown.

OBJECTIVE:

To investigate the effects of cutting the olfactory peduncle on migration of subventricular zone cells in adult rat.

DESIGN:

Randomized controlled experiment.

SETTING:

College of Life Sciences, Univesity of Science and Technology of China; Staff Room of Anatomy, Xuzhou Medical College MATERIALS The experiment was conducted in the Animal Experimental Center , Xuzhou Medical College from September 1997 to January 1999.Totally 25 male adult SD rats were recruited and randomly divided into olfactory peduncle-cutting 30 days group (n=10) and olfactory peduncle-cutting 60 days group(n=15, in which 5 rats were used for immonohisto chemistry).

METHODS:

30 days and 60 days after being cutting olfactory peduncle,the rats were put to death by perfusion for fixation. Consecutive paraffin sections of brain were made. Cellular density and cross section area of RMS were measured. Quantitative analysis of cells in the RMS was performed with immunohistochemical method.MAIN OUTCOME

MEASURES:

The cellular density and cross section area of RMS, the expression of polysialylated neuronal cell adhesion molecule (PSA-NCAM)

RESULTS:

Totally 25 SD rats were recruited. Died for operation and been failure for cutting the olfactory peduncle, so altogether 13 rats used for analysis, 5 rats in 30days group and 8 rats in 60 days group (among that, 3 used for immunohistochemistry). ① Morphologyand quantitative change of RMS after cutting olfactory peduncle The Nissl stained RMS cells were distinguished from adjacent tissue by the characterization of darken stained and dense distribution. There is little condensed nuclear or fragment nuclear. Cellular density at the operation side in the olfactory peduncle -cutting 30 days group and olfactory peduncle -cutting 60 days group was higher than that in the control side (P ＜ 0.01). Relative cellular density of RMS at surgical plane of operation side in the olfactory peduncle -cutting 60 days group was higher than that in the olfactory peduncle -cutting 30 days group(P ＜ 0.01 ). The cross section area of operation side in the two groups was both larger than that of the control side (P ＜ 0.01). There was no difference of cross section area between olfactory peduncle -cutting 60 days group and olfactory peduncle -cutting 30days group (P ＞ 0.05). ②Immunohistochemical reaction of RMS after cutting alfactory peduncle operation 60 days after cutting olfactory peduncle, the accumulated cells in RMS were positive to polysialylated neuronal cell adhesion molecule.

CONCLUSION:

Cutting the olfactory peduncle results in the accumulation of neuronal precursors of RMS and increases the differentiation of migrating neuronal precursors.