Schizophrenia is a psychiatric disorder that is characterized positive, negative, and cognitive symptoms. Positive symptoms usually arise during adolescence and consist of hallucinations. Negative symptoms occur during preadolescence and may include social withdrawals. Cognitive symptoms also arise during preadolescence and usually entail memory and attention deficits. The positive symptoms are often able to be treated, however, negative and cognitive symptoms are more difficult to treat. The researchers attempt to use mice to test the hypothesis of whether developmental abnormalities are the cause of schizophrenia-related symptoms in adults. It is important to study this because with this research, there may be a way to discover how to treat the negative and cognitive symptoms of schizophrenia.
Gαs are G-unit proteins that might contribute to the pathophysiology of schizophrenia. In this particular the dependent variable was the wild-type mice who did not show an overexpression of GαS. The independent variable would be the transgenic mice who showed overexpression GαS.
The subjects of the stated research included transgenic and non-transgenic mice. The tetracycline operator regulates the expression of Gαs. Co-expression of a tetracycline-responsive factor is required in order for the Gαs cDNA to be transcribed. This allows for transgene expression. The researchers decided to restrict the expression of the transgene to the regions of the forebrain neurons. This was done in order to prevent peripheral effects of the transgene that may confuse the analysis of behavioral data. All of the transgenic mice were bred and raised on a 12 hour light-dark cycle with ad libitum access to food and water. There were an equal number of male and female mice used in the experiment. Their ages ranged from two to seven months.
The control group of the experiments conducted consisted of the wild-type mice, monogenic tetO-Gαs mice and monogenic CaMKIIα-tTA mice to be compared to Gαs mice. In order to explain the effects of the transgene expression during development and adulthood, the adult Gαs and baby mice were tested under one of four dox conditions. The first was for Gαs adult mice, and they were given no dox. Dox was given to some mice after about 2 months of age. The third condition was dox from conception until about 2-2.5 months. The final condition was lifelong dox, conception until birth. Lifelong dox was only given in experiments in which the adults failed to reverse a phenotype.
The first experiment conducted was an autoradiographic in situ hybridization. Two (α-35S)-dATP probes were used. One was used solely for transgenic Gαs, the other used for endogenous and transgenic Gαs mice. The measures were taken 2.32 mm lateral from the bregma.
The second experiment involved biochemistry. The mice were killed, their brains were taken out. From the brains, researchers dissected portions of interest from a single hemisphere, these sections were placed in tubes on dry ice. AC activity was measured in membrane preparations from the parahippocampal cortex of control and Gαs mice. cAMP levels were measured using radioimmune competition.
The third experiment conducted to measure startle and PPI. The startle was measured pulses of 90-120 dB were given randomly. PPI was calculated with the following formula: (100-(average startle response for prepulse trials/average startle response for pulse-only trials)X100).
For the fourth experiment, researchers measured locomotor activity in a 41 x 41 cm open field. This field was prepared with 16 x 16 motion detector beams. Horizontal and vertical activities were measured and the percentage of horizontal activity that happened in the periphery was calculated.
The fifth experiment involved a water maze for the mice. This experiment involved assessing spatial learning and memory using the Morris water maze. The mice were trained to sit for 20 seconds on a platform that was submerged in a bucket.