Studies On The Relationship Between The Limbic System And Marginal Division, And Exploring The Specific Candidate Genes For The Marginal Division

PurposesThe term limbic system refers to a heterogeneous collection of structures in the central nervous system. This system includes the cingulate and parahippocampal cortex, the amygdaloid nuclear complex, the hippocampal formation, the septal nuclei, the anterior and midline thalamic nuclei and parts of the basal ganglia. These anatomically connected areas of the brain are physically associated with the maintenance of various visceral and somatic functions related to discriminative, motivational and emotional behaviors and are involved in learning and memory. Although the term "limbic system" is commonly used in basic and clinical neuroanatomical descriptions, there is lack of agreement regarding the neural structures that it comprises. Recent years, studies with some new techniques suggested that limbic circuitry involves multiple areas of the central nervous system, so the search for common characteristics of the limbic system has become an attractive strategy for neurobiologists. Now a type of glycoprotein has been found selectively expressed on the surface of cell bodies, axonal membranes, and growth cones of the neurons in the limbic system. It is termed limbic system-associated membrane protein (LAMP), and regarded as the common molecular marker of the limbic system.The marginal division (MrD), first discovered by Shu Siyun, is a new subterritory of striatum with function related to learning and memory. It forms a belt-shaped zone locating at the caudal margin of the striatum and surrounding the globus pallidus, running dorsoventrally. Based on its location and shape, the area is termed "marginal division". It is distinguished from the rest of striatum by the neuron shape, special connections, function, and intensely expressed immunoreactivities of many neuropeptides andneurotransmitters. Studies in the past years showed that MrD has fiber connection with the reticular part of substantia nigra, the medial part of globus pallidus, Meynert basal nucleus and interior nucleus of posterior plate in thalamus. The oncogene c-fos expressed in some of the limbic structures following stimulating the MrD. MrD also possessed some functions of limbic system, such as learning and memory. All the data suggest the MrD in striatum maybe has some relation to the limbic system. Therefore, in order to further study the relationship between the limbic system and marginal division, and identify whether the MrD belongs to the limbic system, the stress was put on the study about following 3 aspects: (1) the expression of the LAMP in MrD; (2) the functional connection between the limbic system and MrD; (3) the fiber connection between the limbic system and MrD.The brain is divided into numerous regions. Each brain region is characterized by its unique function, connection and architecture. The differential gene expression has primary role in regulating arealization and is established by mechanisms intrinsic to it. The MrD has also the specificity in connection, function and neuron shape, it must have specific gene expression. Thus, preliminary studies on investigating specific candidate genes of the MrD have also been done in this study.Methods and ResultsPart one: 1. The LAMP expression in the MrD and related brain regions: Adult SD rats were deeply anaesthetized with chloral hydrate. The brain was exposed. The MrD, caudate putamen, globus pallidus, prefrontal cortex, hippocampus and cerebellum were precisely dissected under a macroscope. The Western blot and RT-PCR techniques were used to investigate the expression of LAMP and LAMP transcript respectively. The Western blot revealed a specific protein bands at molecular weights of 67KD, the bands from protein extracted from the MrD, hippocampus, globus pallidus and prefrontal cortex were much darker than that from the caudate putamen, and no positive band was detected from the cerebellum. A 200bp band was shown by RT-PCR. The expression of LAMP mRNA was consistent with the protein. The analysis of semi-quantity suggested the expression of LAMP mRNA in MrD was...