Biomedical subjects

D M Jacobowitz

Publications and source records attributed to D M Jacobowitz.

At least 145 records · Page 8Linked to original sources

PubMed1986

Iron deficiency alters discrete proteins in rat caudate nucleus and nucleus accumbens.

Young rats (21 days old) made nutritionally iron deficient, by feeding them a semisynthetic diet containing skimmed milk for 5 weeks, had significantly lowered hemoglobin levels (5.2 +/- 4 g/100 ml). The nonheme iron content in caudate nucleus was decreased by 47%. The behavioral response of iron-deficient rats to apomorphine (2 mg/kg) and the density of 3,4-dihydroxyphenylethylamine (dopamine) D2 receptors, as measured by [3H]spiperone binding in caudate nucleus, were significantly reduced by 70 and 53%, respectively. The possibility that nutritional iron deficiency may affect protein content in brain was investigated by measuring the apparent concentration of proteins in caudate nucleus and nucleus accumbens from iron-deficient and control animals using two-dimensional gel electrophoresis. The data indicate that iron deficiency can affect content in these two brain regions. Significant changes in the content of 10 proteins were noted in the caudate nucleus and nucleus accumbens in iron-deficient rats. The albumin level was significantly increased in both regions studied, whereas the neuron-specific enolase level was increased in the nucleus accumbens and the glial fibrillary acidic protein level was reduced in the caudate nucleus. The significance of these protein content changes, as well as a reduction in content of a 94-kilodalton protein (a molecular size similar to that of the D2 dopamine receptor), remains to be established.

Albumins↗

PubMed1986

The effects of anterior hypothalamic deafferentation on thyrotropin (TSH) biosynthesis and response to TSH-releasing hormone.

The effects of hypothalamic deafferentation on TSH synthesis were studied by making cuts of 180 degrees arc in the anterior hypothalamus (n = 18) or sham cuts (n = 12) in rats. After 21 days, pituitaries were incubated with [35S]methionine (MET), [3H]glucosamine (GLCN), with or without 10(-8)M TRH for 24 h. TSH and free alpha-subunits were immunoprecipitated and analyzed by gel electrophoresis. In the deafferented group as compared to sham, MET incorporation into both subunits of secreted TSH was decreased (alpha, 96 +/- (SE) 9 X 10(3) vs. 180 +/- 20 X 10(3) dpm/mg protein; beta, 35 +/- 9 X 10(3) vs. 84 +/- 15 X 10(3) dpm/mg protein; P less than 0.05). Basal GLCN incorporation into both subunits of secreted TSH was also decreased in the deafferented group (alpha, 6.5 +/- 11 X 10(3) vs. 132 +/- 17 X 10(3) dpm/mg protein; beta, 36 +/- 8 X 10(3) vs. 101 +/- 29 X 10(3), P less than 0.05). In vitro TRH did not stimulate MET incorporation into secreted TSH in the sham controls but did in the deafferented group (alpha, 270% of basal; beta, 374% of basal; P less than 0.01). In vitro TRH increased GLCN incorporation in secreted TSH in both the sham (alpha, 253% of basal; beta, 245% of basal; P less than 0.02) and the deafferented group (alpha, 692% of basal; beta, 630% of basal; P less than 0.01). GLCN/MET ratio, reflecting relative glycosylation, did not differ for sham or deafferented groups but increased 2-fold with in vitro TRH in each group for both secreted subunits (P less than 0.01). Free alpha-synthesis and intrapituitary TSH were not altered by deafferentation or TRH. In summary, 1) anterior hypothalamic deafferentation decreases basal TSH protein and carbohydrate synthesis; 2) such deafferentation increases sensitivity to TRH stimulation of TSH synthesis, most notably apoprotein synthesis; 3) TRH increases relative glycosylation of secreted TSH in both deafferented and sham groups. These data suggest that TRH plays a significant role in regulating basal TSH protein and carbohydrate synthesis, glycosylation of TSH subunits, and subsequent bioactivity.

Animals↗

PubMed1986

Relationships between behavioral rhythms, plasma corticosterone and hypothalamic circadian rhythms.

Circadian rhythms in physiological processes and behaviors were compared with hypothalamic circadian rhythms in norepinephrine (NE) metabolites, adrenergic transmitter receptors, cAMP, cGMP and suprachiasmatic nucleus (SCN) arginine vasopressin (AVP) in a single population of rats under D:D conditions. Eating, drinking and locomotor activity were high during the subjective night (the time when lights were out in L:D) and low during the subjective day (the time when lights were on in L:D). Plasma corticosterone concentration rose at subjective dusk and remained high until subjective dawn. Binding to hypothalamic alpha 1- and beta-adrenergic receptors also peaked during the subjective night. Cyclic cGMP concentration was elevated throughout the 24-hr period except for a trough at dusk, whereas DHPG concentration peaked at dawn. Arginine vasopressin levels in the suprachiasmatic nucleus peaked in the middle of the day. No rhythm was found either in binding to the alpha 2-adrenergic receptor, or in MHPG or cAMP concentration. Behavioral and corticosterone rhythms, therefore, are parallel to rhythms in hypothalamic alpha 1- and beta-receptor binding and NE-release. Cyclic GMP falls only at dusk, suggesting the possibility that cGMP inhibits activity much of the day and that at dusk the inhibition of nocturnal activity is removed. SCN AVP, on the other hand, peaking at 1400 hr, may play a role in the pacemaking function of the SCN that drives these other rhythms.

Animals↗

PubMed1986

Protein patterns in various malignant human brain tumors by two-dimensional gel electrophoresis.

Two-dimensional gel electrophoresis with silver staining was used to study protein patterns in various malignant human brain tumors obtained at surgery. These samples included 20 high-grade astrocytomas (anaplastic astrocytomas and glioblastomas), one low-grade astrocytoma, six juvenile astrocytomas, four ependymomas, and five medulloblastomas. Histological correlates of the sampled tissue were carefully established prior to micropunch sampling. The molecular weight range of these gels was 14,000 to 100,000, and the isoelectric points ranged from 4.7 to 7.0. Proteins that have been identified include albumin, actin, tubulin, glial fibrillary acidic protein, vimentin, glutamic oxaloacetic transaminase, neuron-specific enolase, and the beta-subunit of the guanine nucleotide regulatory proteins. Each type of tumor was found to have a characteristic protein profile that set it apart from the other tumors studied. By providing a convenient tool for the display of a wide spectrum of tumor markers in a single study, two-dimensional gel electrophoresis protein profiles may be useful as diagnostic and prognostic adjuncts. Furthermore, several protein spots that were not noted in normal human cortex were identified in the various tumor gels. Antibodies can be raised against some of these tumor-associated proteins, and their further characterization could provide valuable insights into the biology of these tumors.

Astrocytoma↗

PubMed1985

Effect of reduction of cholinergic input on the concentration of specific proteins in different cortical regions of the rat brain.

The effect of lesioning the nucleus of the tractus diagonalis on the concentration of specific proteins in the hippocampus and the occipital cortex was assessed. Rats received either a sham or an electrolytic lesion and were killed 9 or 35 days later. Tissue samples were removed by microdissection and proteins were separated by two-dimensional gel electrophoresis. Gels were stained with silver, and then analyzed by quantitative computerized scanning densitometry. Of the 143 proteins analyzed, only four were found to be altered in concentration in both brain areas as a result of the lesion. Protein 82 (molecular weight 39,000, pI 6.5) was reduced 71% in the hippocampus and 50% in the occipital cortex 9 days after the lesion, while protein 109 (molecular weight 32,000, pI 6.4) was elevated 140% in the hippocampus and 130% in the occipital cortex at the same time point. Protein 6 (molecular weight 58,000, pI 5.7) was unchanged 9 days after the lesion but was elevated in concentration in both the hippocampus and the occipital cortex 35 days after lesioning. Protein 74 (molecular weight 39,000, pI 5.8) was elevated in concentration both 9 and 35 days after lesioning in the occipital cortex, but only at day 35 in the hippocampus. These results demonstrate that the concentration of these four proteins may be regulated by the cholinergic input to the hippocampus and the occipital cortex. The possibility exists that one or more of these proteins may be related to either the muscarinic or nicotinic cholinergic receptor in rat brain.

Afferent Pathways↗

PubMed1985

Effect of chronic reserpine and desmethylimipramine treatment on CRF-like immunoreactivity of discrete brain areas of rat.

The corticotropin releasing factor-like immunoreactivity (CRF-LI) of discrete areas of rat brain were measured following reserpine (2 mg/kg i.p. for 3 days) or chronic desmethylimipramine (DMI) (20 mg/kg i.p. for 14 days) treatment. Reserpine caused a 40% and 36% reduction in the (CRF-LI) of the median eminence (ME) and posterior pituitary respectively, while DMI caused a 61% rise in CRF-LI of the posterior pituitary only. The results support the role of monoaminergic regulation of CRF release from the ME and further suggest an interaction between monoaminergic and CRF neurons in the posterior pituitary.

Animals↗

PubMed1985

An apparent genetic polymorphism for a protein present in the hypothalamus of Sprague-Dawley rats.

Using two-dimensional gel electrophoresis, an apparent genetic polymorphism was detected in the hypothalamus of a group of inbred Sprague-Dawley rats. The proteins involved in this polymorphism have a molecular weight of 57,000 daltons and isoelectric points ranging from 6.1 to 6.3. These proteins met four criteria that should be met before a positional shift on two-dimension gels can be attributed to a genetic polymorphism. This is the first report of the existence of a genetic polymorphism in the brains of a group of inbred Sprague-Dawley rats. The functional significance of this polymorphism is currently under investigation.

Animals↗

PubMed1985

Primate model of parkinsonism: selective lesion of nigrostriatal neurons by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine produces an extrapyramidal syndrome in rhesus monkeys.

Systemic administration of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) to rhesus monkeys (1.0-2.5 mg/kg i.v.) produces irreversible damage to nigrostriatal neurons. Dopaminergic neurons in the dorsolateral part of striatum were the most vulnerable. The major clinical signs of an extrapyramidal syndrome, but not resting tremor, appeared only in MPTP-treated monkeys suffering from more than 80% reduction in striatal dopamine. No chronic changes in the mesolimbic dopaminergic system were observed. Immunocytochemical staining of the mid-brain with a tyrosine hydroxylase antiserum indicated that MPTP produced a significant decrease of dopaminergic cell bodies in the A9, but not in the A10 ventrotegmental area. Despite greater than 80% decrease in A9 nigral cell bodies, the dopamine content decreased only by 50%. Sprouting of the surviving nigral A9 neurons was observed histologically and neurochemically in the area above substantia nigra. The present behavioral, neurochemical and histological results indicate that MPTP produces an ideal primate model for studying parkinsonism. Selective lesion of more than 80% of the nigrostrial neurons by MPTP is sufficient to produce the major clinical signs of the extrapyramidal syndrome in idiopathic parkinsonism.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗

PubMed1985

Suggestive evidence for a functional unit between mast cells and substance P fibers in the rat diaphragm and mesentery.

A close spatial relationship between serotonin-containing mast cells and substance P-containing nerves was shown by immunohistochemistry using a combination of antisera specific for serotonin and substance P. This supports earlier morphological results suggesting an innervation of mast cells and pharmacological studies which postulate an influence of substance P on the release of histamine from mast cells.

Animals↗

PubMed1985

Galanin potentiates electrical stimulation and exogenous norepinephrine-induced contractions in the rat vas deferens.

In order to evaluate the mode of action of galanin (GAL) on the neuroeffector mechanism of peripheral sympathetic nerve fibers, the effects of this peptide were tested on the electrical stimulated and the unstimulated preparations of the isolated rat vas deferens in the presence of 10(-7) M atropine. The contractile responses, which were mediated predominantly by activation of postganglionic noradrenergic nerve fibers were dose-dependently potentiated by GAL in concentrations ranging from 1 to 50 nM. The facilitatory action induced by GAL in high concentrations (greater than 10 nM) usually returned to the control level at 2-3 min and were tachyphylactic. The potentiating action of GAL was not modified by pretreatment with 10(-7) M propranolol. Contractions produced by exogenous norepinephrine (NE) in the unstimulated preparations were not affected by pretreatment with low concentrations (less than 5 nM) of GAL. On the other hand, the contractions were dose-dependently potentiated 1 min after pretreatment with higher concentrations (greater than 10 nM) of GAL, which recovered 15 min after constant flow washout. Contractions developed by exogenous 5-hydroxytryptamine were not affected, or slightly inhibited, by GAL (1-50 nM). In some preparations without electrical stimulation, high concentrations of GAL caused a slight contraction, which was not blocked by pretreatment with 10(-6) M phentolamine and 10(-6) M tetrodotoxin. These results suggest that GAL receptors exist presynaptically in the rat vas deferens and that stimulation of the receptors by GAL potentiates the release of NE from the nerve terminals during postganglionic sympathetic nerve stimulation. Other mechanisms for GAL action, such as influence on neuronal uptake and catecholamine metabolism, cannot be ruled out.

Animals↗

PubMed1985

Distribution of atrial natriuretic factor-like immunoreactive neurons in the rat brain.

Using antisera generated in rabbits against rat atriopeptin III [alpha-rANP(5-28)] and human alpha-atrial natriuretic polypeptide we mapped the distribution of atrial natriuretic factor-like immunoreactivity throughout the rat central nervous system. Cell bodies were observed in the telencephalon (nucleus interstitialis striae terminalis and between the amygdala centralis and medialis), throughout the diencephalon in all nuclei of the "anteroventral third ventricle", the base of the hypothalamus, the subzona incerta area, the medial forebrain bundle and the medial habenula, in the mesencephalon (mamillary body, substantia nigra lateralis, dorsal and ventral parabrachial nuclei) and very sparse in the medulla oblongata along the fourth ventricle towards the vestibular nuclei, the nucleus tractus solitarii and nervi trigemini. Fibers were present wherever cell bodies were located. The highest relative densities were observed in the anteroventral third ventricle area and the medial habenula. Sparse fibers were also seen in the spinal cord (dorsal and ventral horn and around the central canal) and in the posterior pituitary. The predominance of the atrial natriuretic factor-like perikarya and fibers in the anteroventral third ventricle area suggests an involvement of this peptide in central blood pressure control.

Animals↗

PubMed1985

Binding sites for corticotropin releasing factor in sensory areas of the rat hindbrain and spinal cord.

Binding sites of 125I-Tyr-O-ovine corticotropin releasing factor have been demonstrated in sensory areas of the rat hindbrain and spinal cord mainly in the posterior part of the nucleus tractus solitarii, the substantia gelatinosa nervi trigemini and the superficial layers of the spinal cord (laminae I and II). Specific binding was inhibited in the presence of unlabeled synthetic ovine or rat/human CRF indicating that the receptors recognize both forms of CRF.

Animals↗

PubMed1985

Origin of cholinergic nerves to the rat major cerebral arteries: coexistence with vasoactive intestinal polypeptide.

The distribution and density of vasoactive intestinal polypeptide (VIP) immunoreactive and acetylcholinesterase (AChE)-containing nerves around the cerebral arteries was studied by using whole mounts with or without lesioning the sphenopalatine ganglia. Abundant VIP immunoreactive and AChE-containing nerves were observed around the cerebral blood vessels in normal rats especially in the anterior circulation of the cerebral arteries. VIP-immunoreactivity and AChE-staining was also demonstrated in neurons within the sphenopalatine ganglia. Lesions of the sphenopalatine ganglia resulted in a marked reduction of both VIP-immunoreactivity and AChE activity. In many neurons, coexistence of both VIP and AChE was revealed. These results demonstrate that cholinergic neurons from the sphenopalatine ganglia innervate the cerebral vasculature at the base of the brain, and that VIP and AChE coexists within the same fibers.

Acetylcholinesterase↗

PubMed1985

Galanin-like immunoreactivity in capsaicin sensitive sensory neurons and ganglia.

In rats treated with capsaicin (CAP) as neonates, galanin-like (GA) immunoreactivity is markedly decreased in the trigeminal ganglion and the dorsal root ganglia as well as in the superficial layers of the dorsal spinal cord (laminae I and II), the substantia gelatinosa, the nucleus and tractus of the spinal trigeminal nerve and the nucleus commissuralis. Since CAP causes selective degeneration of primary sensory neurons of the C-fiber type and type B-cells of sensory ganglia, it is concluded that GA in CAP-sensitive primary sensory neurons represents a novel peptidergic system possibly involved in the transformation or modulation of peripheral nociceptive impulses. This system differs from the CAP-resistant GA-like neurons in other brain areas.

Animals↗

PubMed1985

Immunohistochemical localization of a melanin concentrating hormone-like peptide in the rat brain.

Using antisera generated in rabbits against salmon melanin concentrating hormone (MCH) coupled to human thyroglobulin, the distribution of MCH-like immunoreactivity was mapped throughout the rat central nervous system. The distribution of MCH-like immunoreactivity in rat brain is unique and different from the distribution of other neuropeptides. MCH-like immunoreactive perikarya and fibers are predominant in the posterior hypothalamic area, mostly in the medial forebrain bundle-lateral hypothalamic area subzona incerta and the perifornical area. Cell bodies are located mainly in the medial forebrain bundle and in proximity to well defined hypothalamic nuclei. Fibers are seen throughout the rat brain in all neocortical areas, the neostriatum and the amygdala, in the diencephalon in most hypothalamic nuclei, the habenula, the mamillary body and very dense in the medial forebrain bundle and just ventral to the zona incerta ("subzona incerta"). In the mesencephalon there are fibers in the central gray; in the pons-medulla fibers are contained in the dorsal and ventral parabrachial nuclei; in the tegmental area ventral to the fourth ventricle; in the spinal trigeminal area, the substantia gelatinosa and the reticular nuclei. In the spinal cord there are more fibers in the dorsal than in the ventral horn. The posterior pituitary also contained few MCH-like fibers. It is suggested that a peptide similar, but not identical, to salmon MCH is present in the rat central nervous system.

Animals↗

PubMed1985

Identification of neuron-specific enolase and nonneuronal enolase in human and rat brain on two-dimensional polyacrylamide gels.

The location of the enzymes neuron-specific enolase and nonneuronal enolase on two-dimensional gels generated from tissue samples obtained from fresh human and rat cortex has been identified. This identification is based upon the following criteria: comigration on polyacrylamide gels with the appropriate purified protein and staining on nitrocellulose protein blots of human and rat cortex using antibodies specific for each protein. The results show that our preparation of neuron-specific enolase from rat and human brain is highly pure, as only one spot is obtained on two-dimensional gels. Further, the antiserum to neuron-specific enolase is highly specific, as it reacts only with neuron-specific enolase on nitrocellulose blots derived from two-dimensional gels of cortical tissue. The location of these proteins is of interest because it positively identifies two major brain proteins on two-dimensional polyacrylamide gels of fresh cortical tissue. This information will be useful in a variety of future studies aimed at both identifying specific proteins on two-dimensional gels and observing the effects of experimental manipulations on brain and other neuronal proteins.

Animals↗

PubMed1985

Evidence for the existence of atrial natriuretic factor-containing neurons in the rat brain.

Immunoreactive atrial natriuretic factor- (ANF-)positive nerve fibers and cell bodies were observed in the preoptic area, hypothalamus, mesencephalon, and pons of rats. In colchicine-treated animals a large number of immunoreactive ANF-positive cell bodies were seen in the organum vasculosum of the lamina terminalis, in several hypothalamic nuclei (e.g. periventricular, arcuate, and ventral premammillary nuclei), and in the dorsolateral tegmental nuclei of the pons. Varicose nerve fibers containing ANF were generally observed in the vicinity of the cells. These findings indicate that a widespread network of ANF-containing neurons is present in the brain.

Animals↗

PubMed1985

Proteins regulated by gonadal steroids in the medial preoptic and ventromedial hypothalamic nucleic of male and female rats.

Protein profiles of brain areas mediating effects of steroid hormones on copulation were compared between animals in gonadal steroid states predictive of either the presence or absence of copulatory activity. A broad range of proteins present in micropunches of tissue from the medial preoptic area (MPO) and from the ventromedial hypothalamus (VMH) were compared between male and female rats with gonadal steroids present or absent. Half of the animals of each gender were gonadectomized 1 month prior to sacrifice. The remaining males were left intact, while the remaining females were gonadectomized, implanted with estrogen capsules, and injected with progesterone prior to sacrifice. These females were screened for sexual receptivity immediately prior to sacrifice. Proteins from the MPO and VMH of each animal were separated by two-dimensional gel electrophoresis, silver stained, and quantified by computerized optical densitometry. Several proteins differed in density between gels of high-steroid males and and females and between high-steroid and absent-steroid animals of one or both genders. Two previously reported sex differences were replicated and found to depend on activational effects of gonadal steroids. Several interesting reversal patterns were noted between MPO and VMH, including three proteins that were affected by gonadectomy in the MPO of males, but not females, and in the VMH of females, but not males, thus correlating with sexual function. These included serum albumin (a possible index of local area blood flow) and neuron-specific enolase, a glycolytic enzyme of anaerobic metabolism. A probable genetic polymorphism was discovered at a locus whose expression appears to be regulated by gonadal steroids.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗