Galectin-3 is a member of the lectin subfamily that enables the specific binding of β-galactosides. It is expressed in a broad spectrum of species and organs, and is known to have various functions related to cell adhesion, signal transduction, and proinflammatory responses. Although, expression of galectin-3 in some activated neuroglia under neuroinflammation has been well documented in the central nervous system, little is known about the neuronal expression and distribution of galectin-3 in normal brain. To describe the cellular and neuroanatomical expression map of galectin-3, we performed galectin-3 immunohistochemistry on the entire normal rat brain and subsequently analyzed the neuronal distribution. Galectin-3 expression was observed not only in some neuroglia but also in neurons. Neuronal expression of galectin-3 was observed in many functional parts of the cerebral cortex and various other subcortical nuclei in the hypothalamus and brainstem. Neuroanatomical analysis revealed that robust galectin-3 immuno-signals were present in many hypothalamic nuclei related to a variety of physiological functions responsible for mediating anxiety responses, energy balance, and neuroendocrine regulation. In addition, the regions highly connected with these hypothalamic nuclei also showed intense galectin-3 expression. Moreover, multiple key regions involved in regulating autonomic functions exhibited high levels of galectin-3 expression. In contrast, the subcortical nuclei responsible for the control of voluntary motor functions and limbic system exhibited no galectin-3 immunoreactivity. These observations suggest that galectin-3 expression in the rat brain seems to be regulated by developmental cascades, and that functionally and neuroanatomically related brain nuclei constitutively express galectin-3 in adulthood.
Although the level of neuroscience research is rapidly developing with the introduction of new technologies, the method of neuroanatomy education remains at the traditional level and requires improvement to meet the needs of educators and trainees. We developed a new three-dimensional (3D) printed device (human braincutting mold, HBCM) for creating human brain slices; moreover, we demonstrated a simple method for creating semi-permanent ultraviolet (UV) resin-mounted brain slice specimens for neuroanatomy education. We obtained brain slices of uniform thickness (3 mm) through the HBCM; the resultant brain slices were optimal for assessing morphological details of the human brain. Furthermore, we used an agar-embedding method for brain-slicing with the HBCM, which minimized geometrical distortions of the brain slices. Also, we prepared semi-permanent brain serial specimens using an acrylic brain slice frame and UV-curable resin, which was highly compatible with moist bio-specimens. During UV resin curing, neither air bubble formation nor color change occurred. The resultant UV resin-mounted brain slices produced definite coronal sections with high transparency and morphological accuracy. We also performed 3D modeling by stacking brain slice images that differentiated the cortical area and nine subcortical regions via manual segmentation. This method could be a reliable alternative for displaying high-quality human brain slices and would be helpful for students and trainee to understand anatomical orientation from 2D images to 3D structures. Also, this may present an innovative approach for preparing and preserving coronal sections of the normal or pathological human brain.
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