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L L Brown

Publications and source records attributed to L L Brown.

At least 73 records · Page 4Linked to original sources
PubMed1983

A dopamine-sensitive striatal efferent system mapped with [14C]deoxyglucose in the rat.

Rats which had exhibited contralateral rotation following unilateral injection of dopamine (DA) through a striatal cannula were given 0.5 - 50 micrograms DA intrastriatally and then were injected with [14C]deoxyglucose peripherally to measure glucose utilization in the striatum and its projection nuclei. Quantitative autoradiographic techniques were used to measure glucose utilization. Brain areas which showed L-R asymmetries and changes in glucose utilization different from vehicle-injected animals were: the substantia nigra (pars compacta and pars reticulata), the subthalamic n., entopeduncular n., lateral habenula, and deep layers of the superior colliculus. The globus pallidus was affected also, but only in one group for which the injected DA may have spread and affected it directly. Each of these areas receives projections from the striatum or is one additional synapse away. Intrastriatal injections of norepinephrine, isoproterenol, and procaine did not produce changes in glucose utilization in the striatal projection nuclei. The results support the existence of a DA-sensitive strionigral system to both the reticulata and compacta regions of the nigra, and suggest that this activity is paralleled by a strio-subthalamic and strio-entopeduncular-habenular system. The onset of changes in glucose utilization in the entopeduncular-habenular system was later than in the strio-subthalamic and strionigral systems and correlated with the onset of rotation. However, data from 4 animals which did not rotate suggest that each of these systems is necessary but not sufficient for rotation. It is concluded that DA receptors in the striatum play a significant role in the effects of peripherally administered DA agonists on other nuclei, even though most of these other nuclei also have their own DA receptors.

Animals↗
PubMed1981

Catecholamine-containing neurons in cultures of fetal rat hypothalamus: distribution, morphology, and maturation.

The distribution, morphology, and maturation of catecholamine (CA) neurons have been studied in hypothalamic explants from late-gestation rats. CA-containing neurons were identified using the glyoxylic acid technique. CA-containing processes were present from all hypothalamic areas except the preoptic region. Several fiber types were identified. CA neurons in vitro resemble CA neurons in adult hypothalamus. This tissue culture system may be useful in the study of a number of properties of hypothalamus CA neurons.

Animals↗
PubMed1980

Histochemical and pharmacological analysis of noradrenergic projections to the paraventricular hypothalamus in relation to feeding stimulation.

Three techniques, namely, midbrain lesions, fluorescence histochemistry, and brain cannulation, were used in combination to analyze noradrenergic projections to the paraventricular nucleus of the hypothalamus (PVN) and their function in stimulating feeding behavior. The convergence of evidence indicates that the dorsal component of the central tegmental tract (CTT), which ascends through the dorsal pons and then projects through the medial tegmental radiations (TR) into the ventral tegmentum just dorsal to the media lemniscus, contains the crucial noradrenergic axons which innervate the PVN and mediate noradrenergic stimulation of feeding behavior. The primary evidence for this conclusion is that dorsal tegmental electrolytic or 6-OHDA lesions which damaged specifically these fibers invariably caused: (1) a reduction of catecholamine varicosities within the PVN (most notably, fine and moderate-size, rounded varicosities within the parvocellular area); (2) a strong reduction or loss of the feeding response elicited by PVN injection of the presynaptically-acting drugs tranylcypromine and desipramine; and (3) a potentiation of the same response produced by injected norepinephrine. These pharmacological and neurochemical changes in the PVN were reduced in magnitude if the dorsal CTT and medial TR fibers received only partial damage, and these changes did not occur at all if the lesion fell immediately dorsal to these fibers without damaging them. Specific lesions in the ventral tegmentum, which also failed to damage the dorsal CTT and TR axons but instead damaged the ventral component of the CTT, not only failed to disrupt the action of the antidepressant agents but actually potentiated their effectiveness in the PVN. Ventromedial lesions, however, which severed the rostroventral extension of the dorsal CTT and medial TR fibers, had the same behavioral consequences as had the dorsal lesions which damaged this projection at a more dorsocaudal level. Finally, damage to other catecholamine projections had little effect on PVN function in stimulating eating.

Adrenergic Fibers↗
PubMed1980

Histochemical and pharmacological analysis of catecholaminergic projections to the perifornical hypothalamus in relation to feeding inhibition.

Three techniques, namely, midbrain lesions, fluorescence histochemistry and brain cannulation, were used in combination to analyze catecholamine (CA) projections to the perifornical hypothalamus and their function in suppressing feeding behavior. The convergence of evidence indicates that the ventral adrenergic component of the central tegmental tract and dopaminergic projections from midbrain A8 and possibly A9 cell groups contain the crucial fibers which innervate the perifornical hypothalamus and mediate CA suppression of feeding behavior. The primary evidence for this conclusion is that ventral tegmental electrolytic or 6-OHDA lesions which damaged specifically these fibers invariably caused: (1) a marked reduction of CA varicosities in the perifornical area; (2) a strong reduction or loss of the anorectic response produced by perifornical injection of the presynaptically acting drugs amphetamine and mazindol; and (3) a potentiation of the anorectic response produced by perifornical injection of the CA receptor agonists dopamine and epinephrine. Lesions in the dorsal midbrain tegmentum, which left intact the ventral adrenergic and dopaminergic fibers but damaged the compact dorsal tegmental bundle, the dorsal fibers of the central tegmental tract and the medial and lateral tegmental CA radiations, had no apparent effect on the responsiveness of the perifornical hypothalamus to CA drug stimulation, as well as on the CA fluorescence in that region. Lesions in the area of the dopaminergic A10 cells and the midline tegmental CA radiations actually potentiated the effectiveness of the anorexigenic drugs in the perifornical hypothalamus.

Adrenergic Fibers↗
PubMed1979

A direct role of dopamine in the rat subthalamic nucleus and an adjacent intrapeduncular area.

The subthalamic nucleus, a clinically important component of the extrapyramidal motor system, and a lateral area extending into the peduncle contain catecholamine terminals and dopamine receptors coupled to adenylate cyclase. In addition, dopamine agonists administered in vivo enhance glucose utilization in the region. Thus, neuronal function in this region is directly affected by dopamine and dopaminergic drugs.

Adenylyl Cyclases↗
PubMed1979

Carotid sinus syndrome: treatment by carotid sinus denervation.

Hypersensitive carotid sinus is a rare cause of spontaneous syncopal attacks. It must be differentiated from the other more common causes, such as intrinsic cardiac disease, vasovagal responses, postural hypotension and cerebrovascular insufficiency, although it may accompany these conditions. The definition of carotid sinus syncope is syncope elicited by stimulation of a hypersensitive carotid sinus. Nineteen patients with carotid sinus syncope were treated by carotid sinus denervation. Ages ranged from 48 to 83 with a mean of 65.5 years. Symptoms of marked dizziness or syncope were reproduced by gentle compression over the carotid bifurcation, while ECG monitoring revealed bradycardia or transient asystole. Seventeen patients had carotid arteriograms, eleven of which were normal. One patient had stenosis of the external carotid artery, while five had stenosis of the internal carotid. The right carotid sinus was involved in ten patients, the left in three and both sides in six. All patients underwent unilateral or bilateral carotid sinus denervation. Five patients with internal carotid stenosis had concomitant carotid endarterectomy. Complete relief of symptoms or marked improvement was noted in all but one patient. Postoperative follow-up ranged up to 15 years. Carotid sinus denervation is a simple, effective method of treating this disorder.

Aged↗
PubMed1978

Evaluation of wound irrigation by pulsatile jet and conventional methods.

Irrigation of wounds to remove bacteria and foreign material is an essential of wound management along with debridement. The effectiveness of saline lavage by high pressure (50 psi) pulsatile jet irrigation has been compared with conventional gravity flow and bulb syringe procedures. Experimental paravertebral incisional surface wounds in 234 randomized rats were either clean or traumatized and soiled. Wounds in 200 of the rats were seeded with E. coli (log 8.80). Swab specimens of each wound were taken at incision, after seeding, after irrigation, and at three, seven, and ten days after closure. Eulates of more than 1600 specimens were cultured. No anaerobes were found. Irrigation diminished bacterial counts in all wounds, but only pulsatile jet irrigation brought about significant (P less than 0.05) reduction of bacteria in each type of wound. After three days E. coli was significantly diminished in all wounds, regardless of irrigation or none, owing to host defense mechanisms. Nevertheless, clean contaminated wounds were infected at three days but not at seven days after lavage, while traumatized wounds remained infected at ten days except for those initially irrigated by pulsatile jet. Thus, pulsatile jet irrigation removed bacterial from experimental wounds more efficiently than conventional procedures.

Animals↗