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Biomedical subjects

L Abelson

Publications and source records attributed to L Abelson.

12 recordsLinked to original sources
PubMed1994

Gonadal steroid control of preprocholecystokinin mRNA expression in the limbic-hypothalamic circuit: comparison of adult with neonatal steroid treatments.

The neuropeptide cholecystokinin (CCK) is involved in the regulation of female, but not male, reproductive behavior. In both sexes, estrogen regulates the expression of CCK in adulthood within the bed nucleus of the stria terminalis and medial amygdaloid nucleus. These areas are parts of an interconnected limbic system-hypothalamic circuit, the development of which is influenced by estrogen during the early postnatal period. This is the same period during which central nervous system (CNS) expression of CCK is dramatically increased, suggesting that the male and female patterns of CCK expression may be the result of early postnatal exposure to estrogen. In the present experiment, the expression of preprocholecystokinin (pCCK) mRNA was determined by in situ hybridization with an isotopically labeled pCCK complementary RNA and emulsion autoradiography in animals whose neonatal and adult gonadal steroid levels had been manipulated. The number of pCCK-expressing cells in animals that were gonadectomized as adults was determined by neonatal estrogen, but stimulation with steroids in adulthood induced a similar number of pCCK-expressing cells in both sexes in the medial amygdala and bed nucleus of the stria terminalis. Neonatal treatment of females with estrogen or testosterone, followed by ovariectomy in adulthood, eliminated the sex difference in pCCK mRNA expression. Males treated neonatally with the aromatase inhibitor androstenedione (to block metabolism of testosterone to estrogen) and orchidectomized in adulthood had a level of pCCK mRNA expression that was similar to that of ovariectomized females. These data suggest that, during neonatal development, estrogen determines the constitutive expression of pCCK mRNA in the medial amygdala and bed nucleus of the stria terminalis, resulting in higher levels of pCCK mRNA expression in males than in females. However, exogenous gonadal steroids induce the same levels of pCCK mRNA expression in adult females, indicating that the levels of gonadal steroids and the patterns of their secretion are the predominant influences on the sexually dimorphic adult levels of pCCK mRNA expression.

Aging↗
PubMed1992

Differential regulation of alpha-calcitonin gene-related peptide and preprocholecystokinin messenger RNA expression in alpha-motoneurons: effects of testosterone and inactivity induced factors.

alpha-Calcitonin gene-related peptide expression in alpha-motoneurons is regulated by spinal cord transection, axotomy and testosterone, but to date there are no studies which examine the regulation of cholecystokinin expression in motoneurons. In the present study, we compared the regulation of preprocholecystokinin and alpha-calcitonin gene-related peptide messenger RNA levels in motoneurons of the spinal nucleus of the bulbocavernosus. Previously, we demonstrated that manipulations which decrease activity in target muscles of the spinal nucleus of the bulbocavernosus motoneurons increase alpha-calcitonin gene-related peptide message and peptide levels in spinal nucleus of the bulbocavernosus motoneurons. This muscle-nerve interaction is mediated by a soluble factor which is increased by castration. We now report that decreasing plasma testosterone levels decreased preprocholecystokinin messenger RNA levels. Testosterone replacement at the time of castration restored preprocholecystokinin messenger RNA levels to intact values. Injections of crude extracts prepared from denervated bulbocavernosus/levator ani into the homologous muscles of gonadally intact rats increased the levels of alpha-calcitonin gene-related peptide messenger RNA in spinal nucleus of the bulbocavernosus motoneurons. The levels of preprocholecystokinin messenger RNA did not differ in rats injected with denervated bulbocavernosus/levator ani extract or buffer, both of which were significantly higher than in intact, untreated rats. The results of the present experiments imply that levels of preprocholecystokinin and alpha-calcitonin gene-related peptide messenger ribonucleic acid are differentially regulated in spinal nucleus of the bulbocavernosus motoneurons.

Animals↗
PubMed1991

Distribution of mRNAs coding for liver and heart gap junction proteins in the rat central nervous system.

The present study examined the distributions of connexin43 mRNA and connexin32 mRNA in the central nervous system (CNS) of the rat by using in situ hybridization histochemistry. These connexins are the best studied gap junction proteins; connexin32 forms direct cell-cell channels in the liver, as does connexin43 in the heart. There was a differential distribution of cells containing connexin32 mRNA compared with the population of cells which contained connexin43 mRNA, thus implying a regional specificity in the expression of connexins in the CNS. Cells containing connexin43 mRNA were uniformly distributed throughout the gray matter of the neuraxis. Several areas had a higher concentration of cells that express connexin43, such as layer IA of the piriform cortex, supraoptic and paraventricular nuclei of the hypothalamus, anterior cortical amygdaloid nucleus, the reticular part of the substantia nigra, lateral habenula, mesencephalic trigeminal nucleus. Purkinje cell layer of the cerebellum, facial nucleus, prepositus hypoglossal nucleus, and dorsal cochlear nucleus. The pattern of connexin43 hybridization and the morphology of connexin43 mRNA containing cells suggest that this gap junction forming protein is found predominantly in astrocytes. Connexin32 mRNA was detected in discrete cell groups of the gray matter that appeared to be neurons, including cells in layer 2 of the neocortex, layer II of the piriform cortex, pyramidal cell layer of the hippocampus, granule and polymorphic cell layers of the dentate gyrus, islands of Calleja, olfactory tubercle, lateral thalamic nuclei, lateral habenula, and Purkinje cell layer of the cerebellar cortex. A large population of cells in white matter tracts that were labelled with the connexin32 riboprobe appeared to be oligodendrocytes. These studies suggest that neurons and glial cells express connexin32 mRNA, but only astrocytes express connexin43 mRNA. Many of the areas in which connexin mRNAs were demonstrated have electrically coupled cells, morphologically distinct gap junction plaques, and/or have immunocytochemically identifiable connexin proteins. These results indicate that cells with mRNAs coding for intercellular channels have a widespread distribution in the mammalian CNS.

Animals↗
PubMed1991

Distribution of preprocholecystokinin mRNA in motoneurons of the rat brainstem and spinal cord.

The distribution of cholecystokinin (CCK)-immunoreactive neurons in the central nervous system has been questioned because many antisera raised against CCK have been found to cross-react with calcitonin gene-related peptide. The use of in situ hybridization histochemistry has allowed investigators to determine which CCK-immunoreactive cells actually contain the messenger RNA (mRNA) coding for preprocholecystokinin (preproCCK), thus indicating that the peptide is synthesized in these cells. In this study, we report the distribution of preproCCK mRNA in the brainstem and spinal cord of the rat. The main findings of this study are the localization of preproCCK mRNA in motoneurons of cranial nerves IV, V, VI, VII and XII, as well as in motoneurons of the cervical and lumbrosacral levels of the spinal cord. Additionally, cells in lamina III at the cervical and lumbar enlargements contain preproCCK mRNA, suggesting that cells expressing CCK may be important in the processing of sensory information from the appendages.

Animals↗
PubMed1983

Specific association of repetitive DNA sequences with major histocompatibility genes.

The DNA sequence organization of a 17.8-kilobase segment of porcine DNA, containing a functional major histocompatibility (MHC) gene, has been studied. The DNA flanking the MHC gene contains at least 10 distinct repetitive DNA sequence elements, each of which occurs only once within the 17.8-kilobase DNA segment. Their reiteration frequencies in the genome range from 10(2) to 10(4). The genomic organization of seven of these sequence elements has been examined; all are interspersed with other, unrelated DNA sequences. These seven repeated sequences are not generally associated in the genome. However, they appear to be nonrandomly linked in MHC-associated regions of the genome: at least two additional DNA segments containing MHC-homologous DNA also contain sequences homologous to DNA fragments bearing the seven different repeats. Of the seven sequences, four can be detected in splenic total RNA. These results suggest that these repeated elements are specifically associated with the MHC locus.

Animals↗
PubMed1975

Detection of antigens specific for B-lymphoid cultured cell lines with human alloantisera.

Human sera were tested for cytotoxicity to pairs of long-term tissue-cultured cell lines. Each pair had been derived from the same individual and one of the pairs possessed the characteristics of either "T" or "B" cells. The alloantisera used were HL-A-typing reagents or sera obtained from Amish multiparas. Selected cytotoxicity was found against the B-cell lines by direct testing. Cytotoxicity was abolished by absorption with B-cell line but not by absorption with the T-cell lines. The results suggest that a group of allotypic antigens may be expressed exculsively on human B cells.

B-Lymphocytes↗
PubMed1975

Specific human B lymphocyte alloantigens linked to HL-A.

Sera, previously found to react specifically with B lymphoid cultured cells, were tested on isolated T and B peripheral blood lymphocytes in a microcytotoxicity assay. Studies were performed on lymphocytes obtained from several large Amish families. The sera used in these studies were cytotoxic to peripheral blood, B lymphocytes, but not cytotoxic to T lymphocytes. The antigens detected followed the inheritance pattern of HL-A haplotypes. The strong linkage disequilibrium with HL-A antigens suggests that genes controlling the expression of B lymphocyte antigens are linked to genes controlling HL-A alloantigens.

B-Lymphocytes↗