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Biomedical subjects

D M Jacobowitz

Publications and source records attributed to D M Jacobowitz.

At least 109 records · Page 6Linked to original sources
PubMed1989

A study of proteins in the auditory system of rabbits using two-dimensional gels: identification of glial fibrillary acidic protein and vitamin D-dependent calcium binding protein.

Two-dimensional gel electrophoresis and computerized optical densitometry were employed to compare the relative content of proteins across major auditory brain regions in rabbits. Areas examined included the dorsal and ventral cochlear nuclei which receive the primary afferents from the organ of Corti, the lateral superior olivary nucleus which has strong reciprocal relationships with the cochlear nucleus, and the successively more rostral projections of the auditory pathways to inferior colliculus, medial geniculate and auditory cortex. Twelve proteins demonstrated significant decreases and 5 proteins significant increases in content at successively more rostral levels of the auditory system, including 2 proteins which were highly localized to the cochlear nuclei and 2 proteins greatest in amounts in the auditory cortex. One protein which was localized to the cochlear nuclei and lateral superior olive (molecular weight (MW) = 50.3, isoelectric point (pI) = 5.7) was identified as the glial fibrillary acidic protein by reaction of specific antisera on blots. Antisera to the vitamin D-dependent calcium binding protein reacted specifically with one protein (MW = 27.2, pI = 4.8) which was greatest in amount in the lateral superior olive (LSO) versus other auditory regions examined. The significance of these findings rests in the potential for identifying specific markers for cellular elements that are important in auditory function and which might be lost as a consequence of developmental abnormalities or other traumas.

Animals↗
PubMed1989

Immunohistochemical distribution of beta-protein kinase C in rat hippocampus determined with an antibody against a synthetic peptide sequence.

An antibody directed against a synthetic peptide sequence specific for the beta-subtype of protein kinase C (PKC) was used to determine the distribution of beta-PKC in rat hippocampus by immunocytochemistry. PKC was distributed primarily in the stratum oriens and radiatum of the CA1 region. Positive staining cell bodies were only observed after colchicine treatment in pyramidal cells (CA2-CA4) and granule cells of the dentate gyrus. The discrete localization of various subtypes of PKC should provide clues to their functions.

Amino Acid Sequence↗
PubMed1989

Isolation, partial amino acid sequence, and immunohistochemical localization of a brain-specific calcium-binding protein.

A calcium-binding protein (protein 10) having a molecular mass of 29 kDa and an isoelectric point of 5.3 was purified from guinea pig brain. The amino acid sequence of fragments from proteolytic digestion of protein 10 revealed an 86% sequence identity with a calcium-binding protein (calretinin) found in chicken retina. Polyclonal antibodies against protein 10 revealed a specific distribution of this protein within sensory neurons of auditory, visual, olfactory, nociceptive, and gustatory systems as well as other discrete neuronal circuits in rat and guinea pig brain, whereas no specific label was observed in any of several peripheral tissues examined.

Amino Acid Sequence↗
PubMed1989

Rat brain protein kinase C: purification, antibody production, and quantification in discrete regions of hippocampus.

Protein kinase C (PKC), a calcium- and phospholipid-dependent kinase, is highly enriched in rat brain, where it may function in signal transduction processes. We purified rat brain PKC to homogeneity by a three-column procedure of diethylaminoethyl-cellulose, phenyl-Sepharose, and protamine-agarose with a yield of 16% and a final specific activity of 9,600 pmol of [3H]phorbol-12,13-dibutyrate bound/mg of protein. The pure protein consisted of a doublet of 80 and 78 kilodaltons. Rabbit antibodies prepared against a beta-type PKC synthetic peptide sequence (RAKIGQGTKAPEEKTANTISK) showed high specificity and sensitivity for PKC and recognized only the 78-kilodalton form of PKC. Micropunches (300 microns in diameter) of rat hippocampal subregions were solubilized in sodium dodecyl sulfate (SDS) sample buffer, electrophoresed on SDS-10% polyacrylamide gels, and transferred to nitrocellulose. PKC was visualized by 125I-protein A autoradiography and quantified by densitometry. The highest concentrations of PKC were found in the CA1 pyramidal cell layer (0.43 +/- 0.04 OD), with the lowest amounts in the CA3 and CA4 pyramidal cell layers (0.11 +/- 0.02 and 0.085 +/- 0.006 OD, respectively). These results demonstrate a simple way of preparing antibodies against domains of PKC. We also describe a procedure for quantifying the relative amounts of PKC in discrete brain regions.

Animals↗
PubMed1989

Galanin and vasopressin coexist in the rat hypothalamo-neurohypophyseal system.

Using indirect immunofluorescence methods and antisera raised against galanin (GAL) and vasopressin (VP), we have demonstrated both peptides coexisting in the very same cell bodies in the supraoptic and magnocellular paraventricular nuclei and the magnocellular accessory cells of the lateral hypothalamic area. Furthermore, dehydration and salt loading, which is known to cause release and depletion of VP and oxytocin from the neurohypophysis, also caused a marked reduction of GAL-like immunoreactivity in the posterior lobe of the pituitary but had no effect on hypothalamic GAL immunoreactivity. Systemically administered GAL caused a brief small increase in blood pressure with no effect on heart rate. A thousandfold molar concentration of GAL, compared of VP, was required to induce comparable effects on blood pressure. GAL itself had no modulatory effect on VP-induced pressor response. Systemically administered GAL resulted in mild diuresis whereas VP caused complete and sustained inhibition of diuresis. GAL had no effect on VP-induced anti-diuresis effects. The significance of the coexistence and corelease of GAL and VP remains to be elucidated.

Animals↗
PubMed1989

Quantification of proteins in discrete brain regions of androgen-insensitive testicular feminized Tfm mice.

The effect of the testicular feminization mutation (Tfm) on the concentration of specific proteins in the medial preoptic area (MPO), ventromedial hypothalamus (VMH) and parietal cortex (CX) was examined. Adult Tfm and Swiss-Webster male mice were decapitated, the brains were removed and sectioned. Proteins from the three microdissected areas were separated by two-dimensional gel electrophoresis. Gels were stained with silver and then analyzed by quantitative computerized scanning densitometry. Of the 195 proteins quantified, the Tfm mutation significantly influenced the concentration of 16 proteins measured from gels of MPO tissue, 21 from VMH gels and 11 from CX. Of these, three proteins were affected in all brain regions; and three additional proteins were shown to vary in both MPO and VMH. One protein higher in the MPO and VMH of Tfm mice was identified as the glial fibrillary acidic protein. It is suggested that the proteins influenced by the Tfm mutation are regulated by steroids, most likely androgens. Thus, these proteins may prove to be important in hormone-regulated physiological functions.

Androgen-Insensitivity Syndrome↗
PubMed1988

Central muscarinic cholinergic antagonists block wet-dog shakes produced by the TRH analog MK-771 in the rat.

Thyrotropin-releasing hormone (TRH) is known to elicit wet-dog shakes in rats through a central mechanism of action. In the present study, the ability of muscarinic cholinergic antagonists to inhibit TRH-mediated wet-dog shakes was examined. The longer-acting TRH analog, MK-771, at doses of 1.0, 1.5 and 3.0 mg/kg elicited wet-dog shakes in a dose-dependent manner. The centrally-acting muscarinic cholinergic antagonists, atropine and scopolamine, at doses of 5 and 0.8 mg/kg, respectively, significantly reduced the ability of only the highest dose of MK-771 to elicit wet-dog shakes. When the peripherally-acting antagonists, methylscopolamine and methylatropine, were examined, they were not found to significantly reduce wet-dog shakes produced by MK-771 at doses of 5 and 0.8 mg/kg, respectively. The results of this study suggest that cholinergic antagonists inhibit MK-771-induced wet-dog shakes in a noncompetitive manner and support the view that TRH-mediated wet-dog shakes are modulated by central muscarinic cholinergic systems.

Animals↗
PubMed1988

Immunocytochemical localization of peptides and other neurochemicals in the rat laterodorsal tegmental nucleus and adjacent area.

The laterodorsal tegmental nucleus (ntdl) contains a cluster of cells located just medial to the locus coeruleus in the pontine brainstem. The ntdl has been shown to project both rostrally to the forebrain and diencephalon and caudally to the spinal cord. In an effort to characterize this region neurochemically, the present study was conducted to identify a variety of neurochemicals localized within perikarya and fibers of the ntdl and surrounding nuclei. Rats were perfused with formalin, and brain sections were processed for fluorescence immunocytochemistry and acetylcholinesterase (AChE). Of the neurochemicals screened, atrial natriuretic factor (ANF), choline acetyltransferase (ChAT), cholecystokinin (CCK), calcitonin gene-related peptide (CGRP), dynorphin B (Dyn B), galanin, somatostatin, substance P, neurotensin (NT), neuropeptide Y (NPY), vasopressin, vasoactive intestinal polypeptide (VIP), serotonin (5HT), glutamic acid decarboxylase (GAD), and tyrosine hydroxylase (TH) were studied. AChE and ChAT staining revealed that the ntdl contains mostly cholinergic neurons. In addition, brightly reactive substance P and galanin and paler staining CRF, ANF, CGRP, NT, VIP, and Dyn B cell bodies were found within the ntdl. Varicose fibers in this nucleus also contained these peptides in addition to CCK, GAD, TH, 5HT, and NPY. The dorsal tegmental nucleus, dorsal raphe nucleus, locus coeruleus, and the parabrachial region contained a dense and varied assortment of peptides with distinct positions and patterns. This multiplicity of neurochemicals within this area suggests a possible influence on a variety of functions modulated by the ntdl and other closely associated tegmental nuclei.

Acetylcholinesterase↗
PubMed1988

Destruction of cells in the midportion of the locus coeruleus by a dorsal bundle lesion in neonatal rats.

Although insult of the developing noradrenergic neuronal system in the brain has been associated with redistribution of noradrenergic fiber input to various target brain regions, few studies have investigated the effects of such insults on locus coeruleus cell survival. In the present study the dorsal noradrenergic bundle was transected by means of a midbrain knife cut in rats 3 days after birth, and the effects of this lesion were determined approximately 8-10 weeks later. By means of an immunofluorescent histochemical procedure, it was shown that tyrosine hydroxylase-containing fibers and dopamine beta-hydroxylase-containing fibers were markedly reduced in number in the neocortex and hippocampus--regions anterograde to the site of axonal transection. It was further demonstrated that the number of fluorescent fibers coursing through the dorsal bundle was similarly reduced. Sprouting of noradrenergic fibers in the brainstem and cerebellum accompanied the above alterations. When locus coeruleus cell number was determined by counting Cresyl violet-stained nucleoli in serial sections it was found that dorsal bundle transection produced a loss of 17% of the cells of the coeruleus. By dividing the counts for each nucleus into fifths, it was additionally found that approximately 20-25% of those cells comprising the midportion of the nucleus, along a rostrocaudal axis, were the ones destroyed by axonal transection. These findings indicate that a neonatal lesion of the dorsal bundle produces a loss of cells in the midportion of the nucleus locus coeruleus, and that this effect is associated with noradrenergic neuronal hyperinnervation of the brainstem and cerebellum.

Animals↗
PubMed1988

Purification and immunocytochemical detection of a protein that reveals layer V pyramidal cells in the rat cortex.

Protein 36 is a soluble protein isolated and purified from a high-speed supernatant fraction from homogenates of rat brain. To identify this protein in the brain, two-dimensional gel electrophoretograms of soluble proteins were prepared. The protein was separated by ion exchange and gel filtration chromatography. The chromatographic fractions were analyzed by two-dimensional electrophoresis. Protein 36 is a homodimer with a molecular weight of 64,000 Da and monomeric weight of 37,000 Da with an isoelectric point of 6.5. A rabbit antibody was raised to this protein. Immunocytochemical studies indicate that protein 36 is localized in large pyramidal cells, dendrites and axons of layer V of the cerebral cortex. The hippocampus contained cells in the stratum radiata and processes in the stratum pyramidalis. A variety of cell types were also observed in the globus pallidus, thalamus and hypothalamus.

Amino Acids↗
PubMed1988

Multifactorial control of pituitary hormone secretion: the "wheels" of the brain.

An attempt is made to deal with the complexity of the nerve fibers in the median eminence. Visual aids are presented in the shape of "wheels" that depict a dynamic interplay of neurochemicals which result in the release of hormones from the anterior pituitary gland. The multiplicity of neurochemicals in the median eminence is perceived to be responsible for the integrated control of pituitary hormone releasing factors.

Animals↗
PubMed1988

Atrial natriuretic peptide in the central nervous system of the rat.

1. Studies of the presence of atrial natriuretic peptide immunoreactivity and receptor binding sites in the central nervous system have revealed unusual sites of interest. 2. As a result, numerous studies have appeared that indicate that brain atrial natriuretic peptide is implicated in the regulation of blood pressure, fluid and sodium balance, cerebral blood flow, brain microcirculation, blood-brain barrier function, and cerebrospinal fluid production. 3. Alteration of the atrial natriuretic peptide system in the brain could have important implications in hypertensive disease and disorders of water balance in the central nervous system.

Animals↗
PubMed1988

Abolition of vagino-cervical stimulation-induced analgesia by capsaicin administered to neonatal, but not adult rats.

We have previously reported that vagino-cervical mechanical stimulation (VS or probing) produces analgesia in rats. Neonatal treatment with capsaicin (CAP) has been shown to reduce the concentrations of several neuropeptides in dorsal root ganglia, spinal cord, and autonomic ganglia, via a neurotoxic effect. In the present study, we report that CAP administered in the neonatal period abolishes the analgesic effect of probing in adulthood. In addition, we report that the ability of VS to potentiate the lordosis response to manual stimulation of the flanks is abolished by neonatal CAP treatment. By contrast, rats treated as adults with CAP show the typical VS-produced effects of analgesia and potentiation of the lordosis response. Our results suggest that neonatal, but not adult, CAP treatment depletes a neuropeptide(s) that mediates the analgesia and lordosis-inducing effects of VS.

Age Factors↗
PubMed1988

Hypothalamic hypothyroidism caused by lesions in rat paraventricular nuclei alters the carbohydrate structure of secreted thyrotropin.

The effects of hypothalamic hypothyroidism vs. primary hypothyroidism on TSH carbohydrate structure were studied in the rat. Adult male rats with bilateral paraventricular nuclear lesions (n = 10), sham lesions (n = 10), and thyroidectomies (n = 6) were studied 2 weeks postoperatively and compared to normal animals without surgery (n = 6). Pituitaries were incubated in medium containing [3H]glucosamine for 24 h. TSH was immunoprecipitated from medium and pituitary sonicates using anti-TSH beta serum, digested with pronase to obtain TSH glycopeptides, desalted, then analyzed by Concanavalin-A (Con-A) chromatography. Compared to sham controls, hypothalamus-lesioned animals contained a greater proportion of secreted TSH glycopeptides that bound weakly to Con-A, indicating a shift from bisecting and/or multiantennary structures in control animals to biantennary and/or truncated hybrid forms in hypothalamus-lesioned animals. In contrast, thyroidectomized animals, compared to normal and lesioned animals, contained a greater proportion of secreted TSH glycopeptides that did not bind to Con-A, indicating a shift from biantennary and/or truncated hybrid forms to bisecting and/or multiantennary forms. The characteristics of the carbohydrate chains on secreted TSH differed markedly in hypothalamic vs. primary hypothyroidism despite equally low thyroid hormone levels in vivo. Thus, in addition to regulating TSH secretion, hypothalamic hormones alter TSH carbohydrate structure, which may affect its bioactivity and MCR.

Animals↗
PubMed1987

Chronic administration of desipramine or nialamide decreases wet-dog shakes in rats produced by the TRH-analog MK-771.

The effect of chronic administration of the tricyclic antidepressant, desipramine, or the monoamine oxidase inhibitor (MAOI), nialamide, on the ability of the TRH analog, MK-771, to induce wet-dog shakes in rats was examined. MK-771 at a dose of 3 mg/kg produced significantly fewer wet-dog shakes in those animals treated repeatedly with either nialamide or DMI in comparison to those animals treated chronically with saline. Acute administration of these antidepressant compounds did not alter the ability of MK-771 to produce wet-dog shakes in rats. The results of these experiments indicate that TRH responsiveness in the CNS is reduced by chronic but not acute antidepressant drug treatment, and suggest that TRH may be involved in antidepressant drug action.

Animals↗
PubMed1987

Peptidergic innervation of the rat Harderian gland.

The immunohistochemical localization of vasoactive intestinal polypeptide (VIP), Neurotensin (NT), cholecystokinin (CCK), Neuropeptide Y (NPY), and calcitonin-gene-related peptide (CGRP) in rat Harderian glands was examined. Numerous VIP- and CCK-like immunoreactive nerves were found in close apposition to the acini. Sparse numbers of NT-, NPY-, and CGRP-like immunoreactive nerves were observed in close proximity to the acini and blood vessels. Some VIP-like immunoreactive nerves were shown to be co-localized with acetylcholinesterase-positive cholinergic nerves.

Animals↗