Cerebellum and motor learning, motor memory and motor integration: morphology and distribution of neuropeptide Y neurons in rat cerebellar cortex

Xing WANG; Yinping SUN; Xinhua CAI

ABSTRACT

BACKGROUND:

Neuropeptide Y (NPY) neurons are extensively located in various brain regions such as cerebral cortex, caudate-putamen nucleus, syslimbic system, thalamus and brain stem. They are also involved in various brain activities such as motor learning, motor memory and motor integration. Considering the fact that cerebellum can reorganize through motor learning, we tried to identify the morphology and distribution of NPY neurons in rat's cerebellar cortex to obtain the morphologic knowledge that is related to its cerebellar-cortex-based motor learning.

OBJECTIVE:

To investigate the morphology and distribution of NPY -immunoreactive neurons in rat's cerebellar cortex, and discuss the relationship between NPY neurons and cerebellum motor learning and motor memory.

DESIGN:

A single-sample-study based on animal samples.

SETTING:

Anatomy Department, Pathophysiology Department and Morphology Center in Xinxiang Medical College.MATERIALS From July to December 2001, the experiment was performed at the Morphology Center in Xinxiang Medical College. Ten Sprague-Dawley (SD) rats, clean grade, regardless of their gender and weighing 100-200 g,were selected.

METHODS:

After intraperitoneal injection anesthesia and ascending aorta infusion fixation, the cerebellum was taken out by craniosurgery. The cerebellum was immersed in the same fixative fluid for duration of 48 hours, and then was embedded in paraffin. The next step was to make continuous sagittal sections. NPY neurons were identified by SP immunohistochemical staining, using rats cerebral section as the positive control. In the negative control, the first antibody replaced by Bovine Calf Serum(BCS), and the second antibody replaced by 0.01 mol/L PBS. Sequentially the light-microscopic observation and micrography were recorded.MAIN OUTCOME MEASUREMENTS The Morphology and distribution of NPY neurons in rat's cerebellar cortex were taken as main outcome measurements.

RESULTS:

NPY-immunoreactive neurons were distributed in the Purkinje layer of the cerebellum. They had pear-like or spherical shapes, clear and unstained nucleus, unstained axons and dendrites, and their axons stretching out into the granular layer while the reticular dendrites elongated into the molecular layer. NPY-immunoreactive fibers, instead of neurons, were found in the molecular layer and granular layer.

CONCLUSION:

NPY-immunoreactive neurons in the Purkinje layer of the cerebellum may be involved in motor learning, motor memory, visceral activity and higher motor integration.