Biology Reference
In-Depth Information
Fig. 2
Example of GFP coexpression with epitope-tagged transgene. Dual express-
ing HSV viral vector was infused into rat nucleus accumbens shell and was visual-
ized microscopically 4 days later. Hemagglutinin-tagged 5-HT
1B
receptor (
red
)
consistently is localized in the same neurons as GFP (
green
); there is no expression
in glial cells with this vector. The section was imaged using confocal microscopy
at ×20 magnifi cation and the image stack was compressed in the
z
-axis
outcomes that follow the stress experience. Hedonic reactions
were evaluated by measuring the preference for saccharin using a
two bottle choice protocol; stressed animals display reduced pref-
erence for this sweetened solution [
16
] and this is widely inter-
preted as representing an anhedonic state, such as occurs in
depressed individuals. Rats had two drink training exposures to a
0.1 % saccharin drink and then viral vector injections into the
nucleus accumbens shell. Animals were allowed to recover for 2
days and then exposed to four sessions of social defeat (corre-
sponding with the interval of greatest 5-HT
1B
transgene expres-
sion) (Fig.
2
). In our hands, we determined that four consecutive
sessions of social defeat are suffi cient to induce defi cits in animals'
consumption of a rewarding liquid such as saccharin [
16
].
Alternatively, we briefl y considered using cannula so that we could
allow the animals more recovery time, but decided against it
because of the robust scuffl es that are a feature of social defeat.
After 4 consecutive days of social defeat, we tested the animals'
hedonic responsiveness with the saccharin preference test again.
This should be the time just after the peak of virus expression, so if
increased 5-HT
1B
expression in nucleus accumbens shell projection
neurons was blunting the impact of the negative experiences and
enhancing sensitivity to positive experiences and acting like an anti-
depressant treatment, then the stress+5-HT1B group would have
Search WWH ::
Custom Search