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Biomedical subjects

F Bloom

Publications and source records attributed to F Bloom.

At least 37 records · Page 2Linked to original sources
PubMed1983

Topographical study of the neurons containing hpGRF immunoreactivity in monkey hypothalamus.

Hypothalamic neurons producing growth hormone-releasing factor (GRF) have been characterized by immunohistochemistry in monkey hypothalamus, using an antiserum raised against hpGRF1-40, a peptide with GRF activity isolated from a human pancreatic tumor. Cell bodies with hpGRF immunoreactivity were found in arcuate and ventromedial nuclei. From these neurons, bundles of fibers innervate median eminence and appear to terminate in contact with portal vessels. In addition to median eminence, hpGRF immunoreactive fibers were found mostly in the anterior hypothalamus and the arcuate and ventromedial nuclei where they give perineuronal endings. These results correlate with earlier physiological data on hypothalamic control of growth hormone secretion and suggest that GRF is also involved in interneuronal relationships related or unrelated to neurohumoral control of pituitary secretions.

Animals↗
PubMed1982

In vivo and in vitro effects of tetrahydroisoquinolines and other alkaloids on rat pituitary function.

Several tetrahydroisoquinolines (TIQs) were tested for their in vitro and in vivo capacities to modulate prolactin (PRl) and beta-endorphin (beta-end) secretion by the rat pituitary and for their abilities to displace [3H]spiroperidol and [3H]naloxone binding from pituitary and hypothalamic membranes. Receptor binding studies showed that TIQs could be classified as having (a) higher affinity for opiate receptors (tetrahydropapaverine, papaverine, 6-methylsalolinol, 1-carboxysalsolinol and 3',4'-deoxy-norlaudanosolinecarboxylic acid), (b) higher affinity for the dopamine receptor (salsolinol and 7-methylsalsolinol), or (c) approximately equal affinity for the two binding sites (6,7-dimethylsalsolinol and tetrahydropapaveroline, THP). In freely moving male rats, THP produced a several-fold increase in plasma PRL levels. This effect was not altered by co-administration of naloxone but was attenuated by dopamine. In vitro several TIQs reversed the inhibitory effect of dopamine on PRL secretion by cultured anterior pituitary cells. The order of potencies of the TIQs in this system paralleled their order of potencies in the dopamine receptor assay. THP, the most potent dopamine antagonist, also blocked dopamine-mediated inhibition of beta-endorphin secretion from neurointermediate lobe cells in culture. These data demonstrate that THP and some other TIQs can act as dopamine antagonists in radioreceptor assays, in cell culture and in vivo.

Animals↗
PubMed1982

Event-related brain potentials are different in individuals at high and low risk for developing alcoholism.

Event-related brain potentials (ERPs) from normal drinkers with and without a family history of alcoholism were compared. Three separate groups of 10 subjects each (5 with and 5 without a family history of alcoholism) ingested either a placebo or ethanol at 0.56 or 0.94 g/kg. In each comparison, ERP components elicited in conjunction with subjects' decisions about task-relevant stimuli were of significantly reduced amplitude in individuals with a family history of alcoholism. Additionally, both the latency of the positive component and reaction times to correctly detected targets were significantly later in individuals with a positive history of alcoholism than in those without such a history. These group differences were apparent both with and without a challenge of alcohol. The data suggest that brain functions are different in individuals at high and low risk for the development of alcoholism (i.e., those with and without a family history of alcoholism, respectively).

Alcoholism↗
PubMed1982

Blood alcohol levels in rats: non-uniform yields from intraperitoneal doses based on body weight.

1 Sprague-Dawley rats (n = 72) weighing from 125 to 450 g were injected intraperitoneally (i.p.) with 16% (w/v) ethanol to provide 1, 2 or 3 g/kg doses. 2 Resulting blood alcohol levels (BALs) demonstrated a general inadequacy of dose/body weight (g/kg) formulations of ethanol to provide uniform BALs in animals of different weights. 3 BAL differences between heavier and lighter rats were not well accounted for by developmental changes in liver weight or alcohol dehydrogenase activity. 4 From the data, a table was derived of more appropriate ethanol injection volumes to produce 0-300 mg% BALs (20 mg% increments) in rats from 100-500 g (10 g increments).

Animals↗
PubMed1981

The regional distribution of gamma 3-melanotropin-like peptides in bovine brain is correlated with adrenocorticotropin immunoreactivity but not with beta-endorphin.

Immunoreactive (IR)-gamma 3-melanotropin (MSH), -adrenocorticotropin (ACTH) and -beta-endorphin in various areas of bovine brain were measured with their respective radioimmunoassays (RIA). The concentrations of IR-gamma 3-MSH were almost the same as those of IR-ACTH in most areas. Furthermore, in all brain regions, the concentrations of both peptides were lower than those of IR-beta-endorphin. The highest concentration of IR-gamma 3-MSH was found in hypothalamus, followed by thalamus, midbrain and striatum. Gel permeation chromatographic studies showed that the main gamma 3-MSH-like peptide in the hypothalamus, striatum and midbrain was a small form, whose molecular weight is about 4500. These brain gamma 3-MSH-like peptides were also found to be glycosylated.

Adrenocorticotropic Hormone↗
PubMed1980

Distribution of opioid peptides in the pituitary: a new hypothalamic-pars nervosa enkephalinergic pathway.

The distribution of the endorphins, beta-endorphin and enkephalin (Met5-enkephalin and Leu5-enkephalin), was determined in the pars distalis, intermedia, and nervosa of the rat pituitary using both immunocytochemical and radioimmunological methods. Immunoreactive (ir) beta-endorphin was found in pars distalis and pars intermedia. On gel filtration of the pars distalis extracts, beta-endorphin immunoreactivity was eluted in three peaks corresponding to pro-opiocortin (5%), beta-lipotropin (75%), and beta-endorphin (20%). beta-Endorphin was the only component in the pars intermedia. Enkephalin was found in high amount in the pars nervosa. A new enkephalinergic hypothalamic-pars nervosa pathway was observed. Dehydration experiments on normal rats and analysis of the genetically polyuric Brattleboro rat suggest that this enkephalinergic pathway may modulate neurohypophyseal neurosecretion.

Animals↗
PubMed1979

Iontophoresis of Li+ antagonizes noradrenergic synaptic inhibition of rat cerebellar Purkinje cells.

Li salts provide effective therapy for manic-depressive psychosis, but the site and mechanism of this effect are not known. We have tested the ability of Li, applied by microiontophoresis, to modify the responsiveness of rat cerebellar Purkinje neurons to iontophoretic applications of norepinephrine and gamma-aminobutyrate and to the inhibition produced by stimulation of the noradrenergic ceruleo-cerebellar pathway. As previously reported for rat hippocampal neurons, acute exposure to Li produces selective, reversible antagonism of the effects of norepinephrine and the noradrenergic pathway but does not affect inhibitory actions of gamma-aminobutyrate. Collectively, these selective antagonisms of noradrenergic sympatic inhibitions in the cerebellum and hippocampus may indicate a general effect of Li suitable for extended observations in rats exposed to Li for the chronic periods needed to achieve therapeutic effects in man.

Animals↗
PubMed1978

Neurons containing beta-endorphin in rat brain exist separately from those containing enkephalin: immunocytochemical studies.

Well-characterized antisera to porcine beta-endorphin were used to localize immunoreactive sites in cryostat sections of formaldehyde-fixed rat brain by indirect immunohistochemistry. Specificity was established by absorption of immune sera with synthetic peptide fragments. Specific immunoreactivity was localized to neuronal perikarya in the basal tuberal hypothalamus, and to varicose nerve fibers which were distributed to midline nuclear areas throughout the diencephalon and anterior pons. These patterns of reactivity were unaffected by preabsorption of the immune sera with millimolar concentrations of Met5- or Leu5-enkephalin or alpha-endorphin. The beta-endorphin immunoreactive structures were morphologically separate from those cells and fibers reported to react with antisera to the enkephalins. One anti-beta-endorphin serum gave additional immunoreactivity with myelinated axons in limbic cortical zones; when absorbed with purified rat myelin basic protein, only the specific patterns of immunoreactivity remained. Thus, discrete beta-endorphin-containing neuronal circuits exist in rat brain and are anatomically distinguishable from enkephalin-containing nerve cell and fiber pathways.

Animals↗
PubMed1977

beta-Endorphin: endogenous opiate or neuroleptic?

The opiatelike neuropeptide beta-endorphin produces a spectrum of effects that contrasts with that induced by the neuroleptic haloperidol. Rats injected intraventricularly or directly into the periaqueductal gray with beta-endorphin (0.5 to 50 micrograms) exhibited rigid immobility accompanied by the loss of righting reflex; the period of rigidity was preceded or followed (depending upon dose) by a state of hyperactivity. In contrast, no dose of haloperidol tested (0.5 to 12 milligrams per kilogram) produced rigidity, loss of righting reflex, or behavioral excitation. Furthermore, whereas animals injected with haloperidol remained stationary on a vertical grid, rats injected with beta-endorphin typically slid off the grid. Moreover, combined beta-endorphin and haloperidol treatment produced flaccidity in most animals. These results do not support the contention that this opiatelike peptide may be a naturally occurring neuroleptic.

Animals↗