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Developmental changes of MAP2 immunoreactivity in the hippocampus proper and dentate gyrus of the rat
J Biranowska1, B Berdel, B Ludkiewicz
1Department of Anatomy and Neurobiology, Medical University of Gdańsk, Poland.
Abstract:
Microtubules are present in high concentration in the nervous system and are a prominent component of the neuronal cytoskeleton. Microtubules are composed of tubulin and variety of microtubule-associated proteins (MAPs), which have been implicated in the regulation of microtubule assembly and function. MAP2 is the most abundant of these proteins, and it has been extensively characterized in various functional and pathological conditions. In the present study the distribution of MAP2 was examined in each layer of the CA1 and CA3 regions of the hippocampus proper and dentate gyrus in rat development. A total of 40 brains at various ages starting from postnatal day (P) 0 to P90 were examined. After perfusional fixation the brains were frozen and cut on the coronal plane and stained with either cresyl violet or standard immunohistochemical methods using the anti-MAP2 antibody. MAP2 exhibited a somatodendritic pattern of localization in cells of the hippocampus. Staining was most prominent in dendrites and perikarya as well as granules surrounding cell bodies. In a newborn rat's brain immunostaining was intense in granules and faint in perikarya. Between P4 and P21 immunostaining density for MAP2 was stronger and appeared in perikarya, granules, and dendritic trees. After P21 the perikarya and dendrites of the pyramidal layer and stratum radiatum of the hippocampus proper, as well as the molecular and granular layer of dentate gyrus, showed reduced immunoreactivity. In the stratum oriens of the hippocampus and polymorphic layer of the dentate gyrus immunoreactivity was still strong until P90.
Insights
Microtubule-associated protein 2 (MAP2) distribution in the developing rat hippocampus changes significantly after birth. MAP2 shows dynamic somatodendritic localization, crucial for neuronal development and function.
Area of Science:
- Neuroscience
- Cell Biology
- Developmental Biology
Background:
- Microtubules are essential neuronal cytoskeleton components, regulated by microtubule-associated proteins (MAPs).
- MAP2 is a key MAP, abundant in the nervous system, influencing microtubule assembly and neuronal structure.
- Understanding MAP2's developmental distribution is vital for comprehending hippocampal maturation.
Purpose of the Study:
- To investigate the developmental distribution of MAP2 in the rat hippocampus (CA1, CA3, and dentate gyrus).
- To characterize temporal changes in MAP2 localization from postnatal day 0 to 90.
Main Methods:
- Examined 40 rat brains aged P0-P90.
- Utilized perfusional fixation, coronal sectioning, and immunohistochemistry with anti-MAP2 antibody.
- Compared MAP2 staining intensity and localization across hippocampal layers and developmental stages.
Main Results:
- MAP2 exhibited a somatodendritic pattern, concentrated in perikarya and dendrites.
- Newborn rats showed intense granular and faint perikaryal MAP2 staining.
- MAP2 immunoreactivity increased in perikarya and dendrites between P4-P21, then decreased in specific layers post-P21.
- Stratum oriens and dentate polymorphic layer maintained strong MAP2 immunoreactivity until P90.
Conclusions:
- MAP2 distribution undergoes significant dynamic changes during rat hippocampal development.
- These changes reflect the maturation of neuronal structures and synaptic connections.
- The sustained MAP2 expression in specific regions suggests ongoing roles in mature neuronal function.