Indian Journal of Clinical Anatomy and Physiology


The molecular base of development to tolerance for morphine analgesia, expression of CREB & p-CREB protein in dorsal horn of spinal cordof rats: A New insight to explain the tolerance to opioid analge


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Author Details: Satya N. Shukla, SB Ray

Volume : 4

Issue : 2

Online ISSN : 2394-2126

Print ISSN : 2394-2118

Article First Page : 163

Article End Page : 168


Abstract

Introduction: Protein synthesis in cells is regulated by transcriptional activator proteins like cAMP response element binding(CREB) protein, which binds to the DNA molecule near the start of the target gene sequence. This results in the activation of promoter region of DNA by RNA polymerase and the beginning of transcription. Phosphorylation of CREB(p-CREB) greatly increases the transcriptional process. In the present work, the expression of CREB and p-CREB were examined in the spinal cord after morphine tolerance. The underlying cellular basis of morphine tolerance is presently unknown. Presumably increased synthesis of CREB and its phosphorylation to p-CREB might be responsible for tolerance as these have been shown to mediate long lasting changes in brain function.

Aims & Objective:

1.        To study the alteration in the expression of c-AMP response element-binding (CREB) protein and its phosphorylated form (p-CREB) after chronic morphine administration

2.        Immunohistochemical localization of cyclic-AMP response element-binding(CREB) protein expression and it phosphorylated form p-CREBin dorsal horn of thecervical segmentof rat spinal cord

3.        Quantitation     of expression of      CREB and p-CREB with the help of Image Pro Plus 6 Analysis System.

Materials and Method: Adult male Wistar rats were divided to in two groups (n=6/Group) and administered the following: Normal Saline (Group-I), & Morphine (Group-II), for 14 days. Development of Morphine tolerance was determined by the tail-flick test. Expression of CREB and p-CREB was observed by immunohistochemistry using specific antibodies to these proteins. Visualization was done by ABC method. The immuno histochemical staining was quantitatively expressed by measuring the Integrated optical density (IOD) of immunostaining with the help of Image Analysis System driven by Image Pro-plus 6.2 software.
Result and Conclusion: Morphine administration showed increased expression of CREB and p-CREB in dorsal horn of spinal cord. The result of this study demonstrates that CREB and p-CREB may have an important role in the development of morphine tolerance.

Keywords:
CREB- cAMP response element binding (CREB),p- CREB- Phosphorylation of CREB (p-CREB), Immunohistochemical, IOD- Integrated optical density (IOD), Morphine Tolerance, Tai-Flick Test