A Comparison of Phosphodiesterase Type 4 (PDE4) Expression in the BLA in Control and Chronically Stressed Rats Open Access

Stair, Sabrina Lynn (2011)

Permanent URL: https://etd.library.emory.edu/concern/etds/gh93h020x?locale=en
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Abstract

The basolateral nucleus of the amygdala (BLA) is the site of fear-learning, and is part of the neural circuitry disrupted in mood and affective disorders. Evidence suggests that phosphodiesterase 4 (PDE4) inhibitors, which enhance cAMP levels, could be potential treatments for affective disorders. In line with this, unpublished data from our laboratory reveals that PDE4 inhibition causes robust changes in the physiological properties of BLA principal neurons. Thus, aberrant PDE4 activity in BLA principal neurons may contribute to the development of affective disorders. There are approximately twenty-five known PDE4 isoforms, and little is presently known about the baseline expression of PDE4 mRNA and protein isoforms in the BLA. We performed RT-PCR, single cell RT-PCR, western blot analysis, and immunohistochemical analysis to elucidate the expression of PDE4 in the BLA. Our results indicate that of the PDE4A, PDE4B, and PDE4D mRNA transcripts we investigated, all PDE4 isoforms were expressed in the whole tissue BLA samples except PDE4D1 and PDE4D2. Moreover, we found that mRNA transcripts for most of these PDE4 isoforms were also expressed in BLA principal neurons, with the exception of PDE4B1, PDE4B2, and PDE4D8. Western blot and immunohistochemical analysis confirmed the presence of mature peptide for many of these same isoforms. Following exposure to a repeated, four day, unpredictable shock stress paradigm (USS), we found that PDE4A and PDE4D mRNA transcripts were down-regulated in whole tissue samples of the BLA. Importantly, PDE4D mRNA transcripts were also down-regulated in BLA principal neurons following USS. A semi-quantitative densitometric PCR analysis in whole tissue BLA samples revealed that PDE4A1, PDE4A5, PDE4A8, PDE4A10, PDEB3, PDE4B, PDE4D5, PDE4D7, PDE4D8, and PDE4D9 were significantly down-regulated following USS. These PDE4 isoforms may represent important targets for further investigation with quantitative PCR probes and isoforms specific antibodies. Overall, this project has taken the first steps in determining baseline expression of PDE4 isoforms in the BLA, an important task if PDE4 inhibitors are to be used as pharmacological treatments for mood disorders in the future.

Table of Contents


Table of Contents
Introduction………………………………………………………………………………………..1
Methods…………………………………………………………………………………………..11
Results……………………………………………………………………………………………18
Discussion………………………………………………………………………………………..25
Figure 1…………………………………………………………………………………………..34
Figure 2…………………………………………………………………………………………..35
Figure 3…………………………………………………………………………………………..36
Table 1…………………………………………………………………………………………...37
Figure 4…………………………………………………………………………………………..38
Figure 5…………………………………………………………………………………………..39
Figure 6…………………………………………………………………………………………..40
Figure 7…………………………………………………………………………………………..41
Figure 8…………………………………………………………………………………………..42
Figure 9…………………………………………………………………………………………..43
Figure 10…………………………………………………………………………………………44
Figure 11…………………………………………………………………………………………45
Figure 12…………………………………………………………………………………………46
Figure 13…………………………………………………………………………………………47
Figure 14…………………………………………………………………………………………48
Figure 15…………………………………………………………………………………………49
References………………………………………………………………………………………..50

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