2C), the pons (Fig. 2E) and the spinal cord (Fig. 2G, I and K). Less intense staining is seen in other regions of the central nervous system including the piriform cortex, subiculum, lateral and medial habenular nuclei and the pontine area (Table 1). These results are consistent with in situ work done by others characterizing expression of endogenous β4 mRNA (Winzer-Serhan and Leslie, 1997; Zoli et al., 1995). In addition to these regions, endogenous β4 mRNA has been detected in the pineal gland. Our transgene construct did not yield β-gal expression in this region. This is most likely due to the absence of CNR4, a transcriptional regulatory region shown by the Deneris group to be important for pineal gland expression of the clustered nACh receptor genes (Xu et al., 2006). CNR4 is located several kilobase pairs upstream of the β4 promoter region being tested in this work (Xu et al., 2006).
