Radiolabeling of Some Dopamine Receptor Ligands as Models for Brain Imaging

Abstract

Brain imaging is a process which allows scientists and physicians to view and monitor areas of the brain which allow diagnosis and following up different abnormalities in the brain. The measurement of regional cerebral blood flow (rCBF) by single photon emission computed tomography (SPECT) represents the most commonly available and widely applied functional brain imaging technique used in clinical practice. Brain SPECT is now commonly used in diagnosis, prognosis assessment, evaluation of response to therapy, detection of benign or malignant viable tissue and choice of medical or surgical therapy, especially in head injury, malignant brain tumors, cerebrovascular disease, movement disorders, dementia, and epilepsy. The search continues for an optimal brain radiopharmaceutical of high brain uptake and good in-vivo and in-vitro stability as a reliable first step for functional brain imaging. The selection of proper isotope to be used in preparation of such radiopharmaceutical is important because it should have suitable short half life to avoid unwarranted harmful exposure to radiation and suitable photon energy within the range of gamma camera. The two most proper isotopes that fulfill these two precautions are 123I and 99mTc. The selection of either of them depends on the structure of the compound to be labeled. This thesis aimed to prepare radiopharmaceutical compounds effective and specialized for use in nuclear imaging of brain, and the compounds of ropinirole, itopride and prochlorperazine have been selected because of their high ability to access to the brain and bind to the dopamine receptor, labelling of these compounds using 99mTc or 125I radioisotope, and then study the biodistribution of labelled compounds in Swiss albino mice to ensure efficient access to brain. This thesis consists of two chapters:  Chapter I: Preparation and biological evaluation of 99mTc-ropinirole and 99mTc-itopride as radiopharmaceutical models for brain imaging.  Chapter II: Preparation and biological evaluation of 125I-prochlorperazine as radiopharmaceutical model for brain imaging

Following is a brief description of contents of each chapter: Chapter I Preparation and biological evaluation of 99mTc-ropinirole and 99mTc-itopride as radiopharmaceutical models for brain imaging