Biomedical subjects

M C Langub

Publications and source records attributed to M C Langub.

23 records · Page 2Linked to original sources

PubMed1994

Colocalization of natriuretic peptide and estrogen receptor immunoreactivities in preoptic nuclei in the female rat.

Estrogen is known to play an important role in regulating reproductive function in female rats through actions exerted at the preoptic area, a part of the brain that is markedly sexually dimorphic and which contains abundant estrogen receptors. A critical question to our understanding of estrogen's action on the brain is to identify the types of neurons that contain estrogen receptors (ER). Previous studies have shown that atrial natriuretic peptide (ANP) is in abundance in the preoptic area, and that ANP and other natriuretic peptides are capable of regulating gonadotropin secretion. In an effort to determine whether ERs are present in natriuretic peptide-immunoreactive (NP-ir) neurons in the preoptic area of the rat, double label immunocytochemistry was performed. Since ER-ir, as demonstrated with antibody H222 is known to be localized predominantly in cell nuclei, while NP-ir is present in the cytoplasm, single cells can be double labeled. Diaminobenzidine tetrahydrochloride was used for localization of NP-ir neurons, while nickel-enhanced diaminobenzidine tetrahydrochloride was used for localization of ER-ir. The results revealed that many nuclei throughout the preoptic area contained neurons that were ER-ir or NP-ir and that a substantial number were double labeled. Cell counts in selected preoptic nuclei and components, including the anteroventral periventricular nucleus, periventricular preoptic nucleus, medial part of the medial preoptic nucleus, and central part of the medial preoptic nucleus revealed that 13.6%, 11.1%, 13.5%, and 24.4%, respectively, of the NP-ir neurons in these nuclei also contained ER-ir. Collectively, a total of 14.9% of the NP-ir neurons in these nuclei also contained ER-ir.(ABSTRACT TRUNCATED AT 250 WORDS)

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PubMed1993

Localization of C-type natriuretic peptide mRNA in rat hypothalamus.

Central or peripheral administration of C-type natriuretic peptide (CNP) affects numerous neuroendocrine systems, including the hypothalamo-pituitary-gonadal, hypothalamo-pituitary-adrenocortical and hypothalamo-neurohypophysial axes. The present report characterizes the distribution of CNP mRNA in hypothalamus, providing the first definition of CNP-containing neuroendocrine circuits. In situ hybridization histochemical analysis revealed high expression of CNP mRNA in the anteroventral periventricular nucleus (AVPv) and in hypothalamic arcuate nucleus (ARC). Hybridization signals of significantly lower intensity were seen in the medial, median and periventricular preoptic area, the supraoptic, dorsomedial, ventral premammillary and lateral mammillary nuclei and in the posterior hypothalamic area. A few scattered CNP mRNA containing cells were visualized in the medial parvocellular paraventricular nucleus, posterior magnocellular paraventricular nucleus and lateral hypothalamic area. In the AVPv and ARC the pattern of CNP mRNA distribution paralleled that of ANP mRNA. The results indicate a distribution of CNP mRNA associated with key neuroendocrine systems, and underscores the potential importance of this novel natriuretic peptide in neuroendocrine regulation.

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PubMed1992

Estrogen receptive neurons in the preoptic area of the rat are postsynaptic targets of a sexually dimorphic enkephalinergic fiber plexus.

The periventricular preoptic area (pePOA) is a sexually dimorphic component of the rat forebrain that contains a sexually dimorphic Met-enkephalin immunoreactive (ENK-ir) fiber plexus. This plexus is especially dense in the female while only scattered ENK-ir fibers are present in the pePOA of the male. Abundant estrogen receptive neurons are located in the pePOA of both the female and male. This experiment was conducted to determine if estrogen receptive neurons in the pePOA are postsynaptic targets of ENK-ir terminals. Double label ultrastructural localization of estrogen receptor (ER)-ir neurons and ENK-ir fibers was performed using the chromogens 3,3',5,5'-tetramethylbenzidine (TMB) and diaminobenzidine tetrahydrochloride (DAB), respectively. TMB-stained ER-ir neurons contained electron dense crystalline spicules located predominantly in their nuclei. Flocculent DAB reaction product was distributed over membraneous structures in ENK-ir fibers and terminals. Numerous ER-ir neurons were present in the pePOA of the male and female. In females, many ENK-ir terminals, both synaptic and non-synaptic, contacted the perikarya of ER-ir neurons. In contrast, many fewer ENK-ir terminals made contact on ER-ir neurons in the male. Thus, these results provide morphological evidence that ENK-ir neurons can regulate ER-ir neurons in the pePOA. Moreover, because expression of the ENK-ir pePOA fiber plexus is estrogen-sensitive in the female, these results suggest strongly that estrogen may regulate these neurons both pre- and postsynaptically. Finally, these results provide additional evidence for the involvement of the sexually dimorphic pePOA ENK-ir fibers plexus in the control of estrogen-mediated function in the female.

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PubMed1992

Estrogen receptor-immunoreactive glia, endothelia, and ependyma in guinea pig preoptic area and median eminence: electron microscopy.

The presence of estrogen receptors (ERs) in nonneural cells in brain, including glia, ependyma, and endothelia, has not previously been documented with electron microscopy. This study employed immunocytochemistry to investigate whether ER immunoreactivity (ER-ir) is present in glial, ependymal, or endothelial cells in the medial preoptic area (POA) and median eminence (ME) in the brain of gonadally intact female guinea pigs. Tissue sections through these regions were immunostained with monoclonal antibody H222 for ER localization using 3,3',5,5'-tetramethylbenzidine (TMB) as the chromogen. ER-ir cells were identified ultrastructurally by the presence of distinct spicule-like TMB crystals in nuclei. While neurons constituted the clear majority of ER-immunopositive cells, labeled astrocytes, ependyma, and endothelia were also present. Distinct intranuclear TMB crystals were present in astrocytes at the anterior pole of the POA within the preventricular periventricular nucleus, anterior compact subnucleus of the medial preoptic nucleus (MPNa), and organum vasculosum of the lamina terminalis, indicating ER-ir. In the MPNa, cell counts performed at the ultrastructural level revealed that 9.6% (15 of 156) of the astrocytes were ER-ir. To further explore the relationship of ERs with astrocytes, ER/glial fibrillary acidic protein (GFAP) double labeling experiments were performed using TMB and diaminobenzidine tetrahydrochloride for ER and GFAP localization, respectively. These studies verified the presence of ERs in astrocytes at the anterior pole of the POA and demonstrated the presence of ERs in GFAP-ir cells in the ME. Cell counts at the ME showed that 23 of 50 (46%) GFAP-ir cells were ER-ir. ER-ir was also present in scattered ependymal cells lining the third ventricle at the POA and overlying the ME. Typically, approximately four to eight ER-ir ependymal cells were present around the perimeter of the third ventricle, although occasionally small aggregations of greater numbers of labeled cells were observed. Both common ependyma and cells morphologically identified as tanycytes were ER-ir. Some endothelial cells and vascular smooth muscle cells also contained ERs. While approximately 11% of the vessels were lined by ER-ir cells in sections through the MPNa and preventricular periventricular nucleus, approximately 15% of the vessels were labeled in the organum vasculosum of the lamina terminalis. In the ME a greater percentage (59%) of the vessels contained ER-ir endothelial cells. Collectively, these results indicate that in addition to regulating the activity of neurons, estrogen may affect brain function through effects exerted on astrocytes, ependymal cells, and endothelial cells.

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PubMed1991

Ultrastructural evidence for luteinizing hormone-releasing hormone neuronal control of estrogen responsive neurons in the preoptic area.

Both estrogen receptor (ER) immunoreactive (ir) and LHRH-ir neurons and processes are present in the preoptic area of the guinea pig. This experiment was conducted to determine if LHRH-ir terminals interact synaptically with ER-ir cells. A light microscopic dual chromogen immunocytochemical technique employing diaminobenzidine (DAB) and nickel-enhanced DAB for LHRH and ER localization, respectively, revealed that many varicose LHRH-ir fibers coursed in close proximity to ER-ir cells in the anterior part of the preoptic area at the preventricular periventricular nucleus (Pep), suggesting the likelihood of synaptic interactions. Ultrastructural analysis was performed using DAB and 3,3',5,5'-tetramethylbenzidine (TMB) for LHRH and ER localization, respectively. DAB labeling in LHRH-ir neurons appeared as a dense flocculent product dispersed throughout the cytoplasm. TMB stained ER-ir neurons contained electron dense crystalline spicules located predominantly in their nuclei. Numerous TMB labeled ER-ir neurons were present in the Pep, and occasionally occurred in clusters, closely apposed to one another. Many LHRH-ir terminals made synaptic contact or were apposed to unlabeled dendrites, while fewer contacted perikarya. Most significantly, ER-ir neurons showing clear evidence of intranuclear TMB crystals received synaptic input from LHRH-ir terminals. In addition, LHRH-ir terminals lacking synaptic specializations were also in direct apposition to ER-ir perikarya. These results provide morphological evidence that LHRH-ir neurons can regulate ER-ir neurons in the preoptic area. Since LHRH-ir cells are thought to be regulated by estrogen responsive neurons, interaction of LHRH terminals with ER-ir cells may represent a regulatory feedback circuit between the two systems.

3,3'-Diaminobenzidine↗