Biology Reference
In-Depth Information
Apomorphine (Sigma Chemical, USA; 0.25 mg/Kg i.p.) induced rotational behavior was
tested two days after lesioning (Ungerstedt, 1968). Only those animals exhibiting more than
200 complete turns in a 30' period were included in the study. 3, 4, 10, 20, 30, 60 and 120
days after lesioning under i.p. sodium pentobarbitone anaesthesia, and via the aorta, all
animals were perfused with saline solution (0.9%), followed by a fixative solution containing
2% glutaraldehyde and 2% paraformaldehyde in 0.1 M phosphate buffer.
U
LTRASTRUCTURAL
A
NALYSIS
The brains were carefully removed and placed in the same fixative solution during one
hour. Using a dissection microscope, we took small fragments from the dorsomedial quadrant
of the right and left striatum and the right and left SN for its ultrastructural study in a JEOL
100 X II electron microscope (Japan).
Striatal ultrastructural analysis was performed in 50 randomly selected synaptic endings
per striatum. In each synaptic button we observed all its membrane and organelles features,
and we measured (see Fig. 9):
•
The diameters of the presynaptic button using two axes, which were perpendicular
one to each other and intersected at the center of the synaptic terminal; the diameter
was measured directly from the electron microscope screen with a grid placed inside
the eyepiece (Avila-Costa et al., 2005b).
•
The number of dendritic spines or dendrites as postsynaptic targets.
•
The number of perforated synapses (Avila-Costa et al., 2005a).
Figure 9. Synaptic ending (At
1
) showing the two axes measured, establishing a perforated synaptic
contact with a dendritic spine (Sp). At
2
and At
3
also showing the two axes measured and establishing
synaptic contacts with a dendritic shaft (Den).
Synapses were defined by the presence of a clear postsynaptic density facing at least
three presynaptic vesicles. Perforated synapses were identified on micrographs of serial
