Surgery and drug treatments

Surgery and drug treatments

The animals were divided into the following
groups: 1) control, N = 10; 2) thiopental
MPTP, N = 15; 3) thiopental 6-OHDA,
N = 15; 4) K/X MPTP, N = 15, and 5) K/X 6-
OHDA, N = 15. Group 2 and 3 animals were
anesthetized with 40 mg/kg sodium thiopental,
ip, while group 4 and 5 animals were
anesthetized with 85 mg/kg ketamine, ip,
and 3 mg/kg xylazine, ip. MPTP-HCl (100
μg in 1 μL saline; Sigma, St. Louis, MO,
USA) or 6-OHDA (Sigma; 6 μg in 2 μL
artificial cerebrospinal fluid consisting of
8.66 g NaCl, 0.205 mg KCl, 0.176 g CaCl2 .
2H2O, and 0.173 g MgCl2 . 6H2O in 1 liter of
water, plus 0.2% ascorbic acid) was infused
into the SNc through a 30-gauge stainless
steel needle at a rate of 0.33 μL/min, at the
following coordinates: anteroposterior -5.0
mm from the bregma, mediolateral ±2.1 mm
from the midline, and dorsoventral -7.7 mm
from the skull. During the first 5 postoperative
days the animals were fed a pasty diet
consisting of a mixture of crumbled ration
and water. After that time, the animals were
no longer aphagic or adipsic, and presented
no gross motor deficit that could affect their
performance during the memory tasks. Two
additional groups were submitted to surgery
in which artificial cerebrospinal fluid was
infused under thiopental or K/X anesthesia.
These treatments did not significantly affect
cell death, as shown in the Results section by
the striatal levels of dopamine and 3,4-dihydroxyphenylacetic
acid (DOPAC) when
compared to the non-operated group (Figure
3). These data were pooled and referred to as
the control group in the Results section.