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F E Bloom

Publications and source records attributed to F E Bloom.

At least 379 records · Page 21Linked to original sources
PubMed1975

Ontogeny of monoamine neurons in the locus coeruleus, raphe nuclei and substantia nigra of the rat. II. Synaptogenesis.

Synaptogenesis was studied in the monoamine (MA) cell groups locus coeruleus (LC), dorsal and medial raphe nuclei (RN) and substantia nigra, zona compacta (SN) between day 18 of gestation and postnatal day 60 using ethanolic phosphotungstic acid (E-PTA) to visualize synaptic profiles. Nuclear area, and cellular packing density (inversely proportional to area of neuropil) were also determined. As determined using the E-PTA method, synaptogenesis begins in the neuropil of the SN first, on or before 18 days of gestation, and in the LC and RN at 19 days. Synaptogenesis on MA cell perikarya is first observed in the SN, on or before 18 days, and in the LC and RN at 20 days. The onset of somatic synaptogenesis coincides with the beginning of nuclear growth and development of the neuropil (decrease in cellular packing density) in all MA cell areas, raising the possibility of common factors in the initiation of these processes. Nonsynaptic contacts precede the appearance of synaptic profiles both in the neuropil and on the somata of the MA cells of the LC, RN and SN, and may represent precursors of mature synapses or desmosome-like contacts. Somatosomatic nonsynaptic contacts occur only prenatally between adjacent MA neurons in the LC, RN and SN. Although some synaptogenesis occurs prenatally in these MA cell groups (indiciating that these parts of the MA circuitry may be functional before birth), most of this synaptogenesis occurs postnatally and continues into adulthood. Since such synaptogenesis does not begin until 2-4 days prior to birth, whereas these neurons and their processes exhibit MA fluorescence as early as 12-14 days of gestation, they apparently are capable of synthesizing transmitter and proliferating terminals before they themselves are innervated.

Animals↗
PubMed1975

Catecholamines in mutant mouse cerebellum: fluorescence microscopic and chemical studies.

Catecholamine-containing fibers have been examined in the cerebella of normal and hypocerebellar mutant mice using Falck-Hillarp and glyoxylic acid histofluorescence techniques. The amounts of norepinephrine and dopamine were also determined chemically in the same mutants. Green fluorescent fibers in cerebella of normal mice are similar in size and distribution to those described in the rat. Weanling and adult weaver, reeler and staggerer mice all manifest greatly increased specific catecholamine fluorescence per unit area in cerebellar cortex, but the patterns of fluorescent fibers are distinctive. In weaver, the fibers are of normal diameter, surround Purkinje cell bodies and appear to climb along major dendrites. In reeler, similar fibers form a plexus around cortical and non-cortical Purkinje cells; relatively normal fluorescent fiber patterns are present in well-organized cortical regions, while stouter disoriented fibers course through the shallow molecular layer in disorganized regions. Staggerer cerebellar cortex exhibits the greatest fluorescence with most terminals appearing as matted tangles adjacent cell bodies. Clearly defined fibers, however, can be distinguished in the molecular layer running perpendicular to the pia or for long distances in the coronal plane parallel to the pia. The major catecholamine determined chemically is norepinephrine. Reeler cerebella contain normal absolute levels and a doubled concentration of norepinephrine. In contrast, and despite the fluorescence findings, the total norepinephrine content of weaver and staggerer cerebella is significantly reduced and concentrations are not significantly different from normal.

Animals↗
PubMed1975

Immunofluorescent localization of cyclic AMP in toad urinary bladder: possible intercellular transfer.

By use of an immunofluorescent cytochemical staining technique, adenosine 3',5'-monophosphate (cyclic AMP) has been localized in toad bladder epithelial cells. Within 2 minutes after addition of vasopressin, staining intensity increases in both mitochondria-rich and granular cells. This finding, taken together with the precise anatomical relation between these two epithelial cell types and the observation that after separation of the two cell types vasopressin stimulates cyclic AMP accumulation in only mitochondria-rich cells, suggests that cyclic AMP may be transferred from mitochrondria-rich to granular cells as part of the response of the toad urinary bladder to vasopressin.

Animals↗
PubMed1975

Cyclic AMP and cyclic GMP may mediate opposite neuronal responses in the rat cerebral cortex.

Electrophysiologically identified pyramidal tract neurons in the rat cerebral cortex were tested with norepinephrine, acetylcholine, adenosine 3',5'-monophosphate (cyclic AMP), and guanosine 3',5'-monophosphate (cyclic GMP) applied by microiontophoresis. The neurons were usually inhibited by norepinephrine and cyclic AMP, but excited by acetylcholine and cyclic GMP. These opposing responses of pyramidal tract neurons to cyclic AMP and cyclic GMP suggests that these two nucleotides could function as reciprocal intracellular second messengers for norepinephrine and acetylcholine, respectively.

Acetylcholine↗
PubMed1975

Monoaminergic neurotoxins: are they selective?

Introduction of 6-hydroxydopamine into the cerebrospinal fluid produces a selective destruction of adrenergic pathways. However, the selectivity of interstitial injections of 6-hydroxydopamine for catecholamine elements is critically dependent upon the dose and volume of injection must be evaluated by biochemical and cytochemical indices.

Animals↗
PubMed1975

A rapid, simple and more sensitive method for the demonstration of central catecholamine-containing neurons and axons by glyoxylic acid induced fluorescence: I. Specificity.

Perfusion fixation with a mixture of paraformaldehyde and glyoxylic acid facilitates the histochemical demonstration of catecholamine-containing brain neurons. With this fixation, sections can be cut reproducibly with a cryostat and the fluorophore developed by immersion in glyoxylic acid without freeze-drying. Large sections of brain can be examined by fluorescence microscopy within 1 hour of fixation or stored for later examination. The properties of the fluorophore and the location of the fluorescent elements is identical with the neurons and terminal arborizations demonstrated by previous glyoxylic acid methods. Monoamine oxidase inhibition before fixation results in moderately increased fluorescence of terminals and perikarya, while all glyoxylic acid induced fluorescence is abolished by pre-treatment with reserpine. The rapidity and simplicity of this technique may make fluorescence histochemistry of central catecholamine pathways more accessible to psychopharmacologists.

Animals↗
PubMed1975

Chlorpromazine induced hyperphagia in the rat.

During a four month period, 20 rats treated with subcutaneous injections of chlorpromazine (CPZ), at any dose tested, gained less weight than saline treated controls. However, increased feeding did occur on the first day of CPZ treatment if the animal was drug free for at least two days prior to treatment. The "first day" hyperphagia was a time limited response that did not occur until 8 hours after CPZ injection and lasted only one day. During the period of hyperphagia, treated animals showed increased motivation to obtain food. Although sedation is a marked effect of CPZ and may be the reason for the delayed onset of hyperphagia, sedation with a different drug does not cause hyperphagia. It is suggested that accumulation of a metabolite of CPZ may interfere with the feeding response and cause the hyperphagia to disappear after the first day of treatment.

Animals↗
PubMed1975

Characteristics of the release of adenosine 3':5'-monophosphate from micropipets by microiontophoresis.

The transfer number for radio-labelled cyclic AMP released from microiontophoretic pipets into brain pieces was determined for a large number of samples by radioassay. Release of cyclic AMP was linearly related to both iontophoretic current intensity and time as predicted by Faraday's Law. The results revealed that cyclic AMP has a rather low transfer number. In addition, an unusually large amount of variation of release, both within and among pipets was found under a variety of times and currents. The cause of the variation is not known but could be due to the unusual structure of the cyclic AMP molecule and the fact that it must be iontophoresed as a negative ion. These characteristics of cyclic AMP release may contribute to the difficulty in obtaining positive responses from appropriate neuronal target cells in vivo.

Animals↗
PubMed1975

Modern concepts in electrophysiology for psychiatry.

The emergence of specific concepts of possible neuronal pathophysiology in mental disorders has recently been accelerated by the realization that the central catecholamine and indoleamine pathways show potent and widespread actions in animal experiments. These functional properties have been characterized in part by new methods of neuronal circuit analysis, more specific methods of neuronal cytochemistry, and by extensive exploitation of more classical electrophysiological methodologies for the assessment of synaptic transmitter identification and mechanism, the results of experiments at the cellular level have permitted additional studies to be done on the possible behavioral significance of the events regulated by monamines in the awake animal, When the cytochemical and electrophysiological and behavioral exeriments are considered as connected aspects of the same brain sub-systems, then the simple electrophysiological concepts of excitation and inhibition seem inadequate to explain the integrative, amplifying and biochemical actions which can be performed by experimental manipulation of central monamine pathways.

Animals↗