Repeated immobilization stress reduces the gene expression of the type 1 and 2 IP3 receptors in stellate ganglia

Inositol 1,4,5-trisphosphate (IP(3)) is one of the second messengers produced by phosphoinositid hydrolysis and triggers IP(3) receptor (IP(3)R) mediated calcium release from intracellular pools. To determine whether immobilization stress affects the gene expression and protein level of IP(3)R in stellate ganglia, animals were immobilized once for 2h and/or for 7 days, 2h daily. After decapitation, stellate ganglia were extirpated and the gene expression of IP(3) receptors was evaluated. Protein levels of IP(3) receptor were measured by Western blot analysis using the antibody against IP(3) receptor. In the present work, we clearly show that type 1 and 2 IP(3) receptors, but not the type 3 IP(3) receptor, are expressed in stellate ganglia. Both types, type 1 and 2 IP(3) receptors, are not significantly affected by single 2h immobilization stress on mRNA and protein level. However, gene expression of both these types is significantly reduced by repeated immobilization stress for 7 days, 2h daily. The IP(3) receptor protein is reduced as well. Physiological relevance of our observations remains to be elucidated.