Artur Mayerhofer

Vitamin d nuclear binding to neurons of the septal substriatal and amygdaloid area in the siberian hamster phodopus sungorus brain

Autoradiographic experiments were performed on brains of Siberian hamsters (Phodopus sungorus) injected with tritiated 1,25-dihydroxycholecalciferol. Nuclear labeling was prevented in the presence of excess unlabeled hormone. Strong nuclear concentration of radioactivity was observed in neurons of the nucleus basalis of Meynert, the medial septal nucleus, the nucleus of the diagonal band of Broca and the central amygdaloid group. The latter has been defined as consisting of the central nucleus of the amygdala, its extension into the sublenticular part of the substantia innominata of Reichert, and the lateral division of the bed nucleus of the stria terminalis. All these structures have been reported to be involved in memory and other cognitive processes, and to be affected by age-dependent neurodegenerative disorders such as Alzheimers disease. Corresponding localization of 1,25-dihydroxycholecalciferol receptor sites in these select basal forebrain nuclei of the Siberian hamster may implicate vitamin D (soltriol), the steroid hormone of sunlight, in memory processing.

Nuclear receptor sites for vitamin D-soltriol in midbrain and hindbrain of Siberian hamster (Phodopus sungorus) assessed by autoradiography

SummaryAutoradiograms were prepared from midbrains and hindbrains of male and female Siberian hamsters (Phodopus sungorus), kept under short-day or long-day illumination, after injection of tritium-labeled 1,25-dihydroxycholecalciferol (vitamin D, soltriol). Concentration and retention of radioactivity was noted in nuclei of certain neurons, glial cells, and ependymal cells, and in choroid epithelium. Labeled neurons of varying intensity were found throughout the brainstem in distinct populations at characteristic topographical sites, which include cranial nerve motor nuclei, the nucleus (n.) reticularis tegmenti pontis, the caudoventral region of the n. raphe dorsalis, the n. trapezoides, the n. vestibularis lateralis and n. vestibularis superior, neurons in the various nuclei of the sensory trigeminus, accessory optic nuclei, scattered neurons in nuclei of the reticular formation, the n. ambiguus, certain cells in the area postrema, and many others. Glial cells with nuclear labeling, probably microglia, were scattered predominantly in or near myelinated nerve fascicles. The choroid epithelium showed strong nuclear labeling throughout the ventricle. Nuclear labeling of ependyma was variable and weak, mainly at ventral and lateral extensions (recesses) of the ventricle. The extensive presence of nuclear binding in select neural structures indicates that vitamin D exerts specific genomic effects on cell populations that are known to be involved in the regulation of motor, sensory, autonomic, neuroendocrine, metabolic, and immune functions. The results of these studies, in conjunction with those from other brain and peripheral tissues, recognize vitamin D-soltriol as a steroid hormone with a wide scope of hormone-specific target cells, similar to estrogen, androgen, and adrenal steroids, and which are topographically distinct and characteristic for its functions as the steroid hormone of sunlight.

Vitamin D (Soltriol) receptors in the choroid plexus and ependyma: Their species-specific presence.

The present study describes the appearance of high-affinity nuclear binding sites (receptors) for 1,25-dihydroxyvitamin D(3) (soltriol) in organs that contribute to the blood-brain barrier such as choroid plexus and ependyma in the Djungarian hamster Phodopus sungorus, C57BL/6J mice, and vitamin D-deficient Sprague-Dawley rats. Using autoradiography, after injection of 1,25[(3)H]dihydroxyvitamin D(3) specific nuclear neuronal labeling is seen in all species in certain regions of the brain. Choroid plexus and ependyma show distinct species differences. In female and male Phodopus, constantly raised under long-day conditions or transferred for S weeks to a short-day cycle, nuclear receptors for 1,25-dihydroxy-vitamin D(3) are present in the choroid epithelium of all ventricles, while nuclear labeling is inconspicuous or absent in nonepithelial cells of the choroid plexus and most of the ependyma. Some ependymal cells in select regions of all ventricles display nuclear labeling that includes portions of the lateral ventricle, ventral and dorsal third ventricle, aqueduct, and fourth ventricle, but is comparatively weak. Differential presence of radioactivity in ventricular regions was noted, suggesting binding to proteins in cerebrospinal fluid. In mice and rats nuclear binding is absent or inconspicuous in choroid epithelium and ependyma under conditions when strong nuclear labeling is present in neurons of the nucleus centralis of the amygdala and cranial motor nerve nuclei. Vitamin D synthesis is dependent on sunlight and its levels change with season. Therefore, it is suggested that vitamin D (soltriol) regulates functions of choroid plexus and ependyma in the Djungarian hamster, probably thus serving the transmission of circannual changes in rodent species with strong seasonal adaptations.

Sites of action of soltriol (vitamin D) in hamster spleen, thymus, and lymph node, studied by autoradiography

SummarySibirian hamsters (Photopus sungorus) were injected with3H dihydroxycholecalciferol (vitamin D, soltriol). Autoradiograms of spleen, thymus, and lymph nodes revealed nuclear concentration of the hormone in a select population of cells in all of these organs. In the spleen, labeled cells were abundant in the red pulp, but sparse in the white pulp. In the periarterial lymphatic sheath (PALS) labeled cells were found predominatly at the outer rim, with a few scattered labeled cells in the inner PALS and in the marginal zone. Lymphocytes, including pyronin-positive plasma cells, did not display nuclear labeling. In the red pulp, some of the labeled cells contained pigmented inclusions in the cytoplsm, while most of the labeled cells did not appear phagocytic under the conditions of the experiment. In the thymus, labeled cells were most numerous in the medulla, but sparse in the cortex. Many of the thymic target cells were larger than the unlabeled lymphocytes, with a large and pale nucleus, sometimes containing a distinct nucleolus, and with large and dendritic cytoplasm, having the appearance and distribution of epithelio-reticular cells. In lymph nodes, scattered labeled cells were conspicuous in or near the subcapsular sinus, while other cells did not concentrate radioactivity in their nuclei.The results indicate that nuclear receptors and direct genomic actions for soltriol exist in certain cell populations of lymphatic tissues that probably include reticular cells and a subpopulation of macrophages. These target cells may mediate effects of the steroid on lymphocytes that appear to have no or only very low numbers of nuclear receptors.

A radioimmunoassay program for Lotus 1–2–3

Spreadsheet programs have become very popular as convenient ways of performing mathematical operations, as well as entering and organizing data. This paper describes how Lotus 1-2-3 can be used to calculate the results of a radioimmunoassay, a widely used technique in biomedical laboratories.

Genetics and Luteinizing Hormone Receptors

Testicular luteinizing hormone receptors (LH-Rs) that bind either LH or human chorionic gonadotropin (hCG) are required for the differentiation of the Leydig cell (1). This is indicated by the correlation between the onset of Leydig cell differentiation and the appearance of hCG during the development of the human fetus. The number of Leydig cells also correlates with the levels of hCG during pregnancy. Leydig cells, and therefore LH-Rs, are present by week 8 of pregnancy in the human (2–4), and by day 15 in rodents (5).