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Query: UMLS:C0038187 (starvation)
 24,951 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

1. The kinetics of transport of glucose and four other hexoses through the blood-brain barrier were studied with a tritiated-water reference technique in the anesthetized rat. Brain clearance of [14-C]hexose was measured 15 s after a single injection of the hexose and 3-HOH reference into the common carotid artery. 2. Saturation of brain clearance of [14-C]hexose conformed to Michaelis-Menten kinetics. Linear transformation of the uptake data yielded the Km of carrier-mediated hexose transport: 2-deoxy-D-glucose 6 mM, D-glucose 9mM, 3-O-methyl-D-glucose and D-galactose 40 mM. A maximum transport velocity of 1.56 mumol/g per min was calculated and shown to be constant for all five hexoses. 3. The kinetics of 3-HOH and 3-0-methyl-D-[14-C]glucose efflux from brain to blood were studied with a modification of the water reference technique. An estimate of cerebral blood flow, 0.56 ml/g per min, was made from the efflux rate constant for 3-HOH, 0.61 min-1. The fractional extraction of 3-0-methyl-D-[14C]glucose uptake from blood was estimated from the efflux rate constant, 0.22 min-1, for this sugar and found to be 0.25. This value approximated the fractional extraction of 3-0-methyl-D-[14-C]glucose uptake that was determined from influx studies (0.24). These results indicated that the bidirectional movement of glucose across the blood brain barrier was symmetrical, which suggested that barrier sugar transport is equilibrative and not active. 4. Blood-brain barrier sugar transport was shown to be reversibly inhibited by phloretin, yet no modulation of transport was demonstrable after 2 or 8 days of starvation. Finally, regional analysis (olfactory bulb, caudate-putamen nucleus, thalamus-hypothalamus, and inferior-superior colliculi) demonstrated that, in addition to blood-brain barrier permeability, brain clearance of glucose was a function of cerebral blood flow.
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PMID:Kinetics of blood-brain transport of hexoses. 112 40

To determine the effect of starvation on brain insulin receptors, rats were fed 4 g of chow/day for 14 days and then P2 fraction membranes were prepared from different brain regions. Compared to the fed state, there was an 18% reduction of insulin binding in olfactory bulbs from starved animals, but no change in the cerebellum, frontal cortex, amygdala, medial hypothalamus or lateral hypothalamus. A 15% reduction of olfactory bulb insulin binding was obtained by totally starving animals for four days. When membrane content was measured using the plasma membrane marker Na/K ATPase, insulin binding decreased by 26% and 14% in olfactory bulb membranes from starved and totally starved animals, respectively. The starvation-induced change in olfactory bulb binding was due to a loss of binding sites and not a decrease in binding affinity. Non-specific catabolism of protein and a change in the composition of membranes following starvation were excluded as causes for this effect. As streptozotocin induced diabetes had no effect on brain insulin binding, it was concluded that hypoinsulinaemia associated with starvation had not caused the reduction in olfactory bulb binding. Under similar conditions of starvation and diabetes, insulin binding in liver plasma membranes increased 26% and 38%, respectively. At 8 and 14 days of starvation, the reductions in olfactory bulb insulin binding and body weight were similar. On refeeding for three days, there was no increase in insulin binding, although body weight increased 7%. On refeeding for eight days, olfactory bulb insulin and body weight had returned to near normal.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Effect of starvation on insulin receptors in rat brain. 274 26

Seven specimens of the African lungfish ranging in size from 4 to 350 gm were used for the study of changes in the olfactory nerve and bulb during postembryonic growth as expressed by the increasing number of lamellae of the olfactory organ. Serial semithin sections were used, and the data were studied mathematically. The number of axons of the olfactory nerve, the surface area of the bulb, and the number of mitral cells increase exponentially; the mitral cell density decreases exponentially; and the calculated average convergence (counted axons/counted mitral cells) of axons onto the cells of the bulbar relay increases exponentially. Convergence figures obtained are smaller than those cited by other authors; two factors might explain this: first the mode of calculation, and second the fact that every year this fish undergoes a 6-month starvation stage marked by degeneration of the primary olfactory structure. A preliminary view of the primary olfactory pathway using serial-section reconstructions is proposed: An orderly projection of the mucosa onto the bulb takes place after a 90 degrees rotation of the system of two perpendicular axes which apply to both the olfactory organ and the olfactory bulb. This study suggests an original attempt at relating the postembryonic change in convergence and projection to the primary processing of the olfactory message.
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PMID:Functional anatomy of the peripheral olfactory system of the African lungfish Protopterus annectens owen: development of the primary olfactory pathway during postembryonic growth. 609 36

An anatomical functional study of the olfactory system of Protopterus annectens along the course of the primary olfactory neuron was made by means of macroscopic and microscopic methods on samples of specimens weighing from 3 to 1.250 gm. The olfactory organ, opening by anterior and posterior nostrils into the oral cavity, may be considered a macrosmatic fish type according to the repartition of receptor areas along parallel grooves and on the basis of its active irrigation mechanism. A morphometric study of Protopterus, using a set of seven specimens weighing from 4 to 350 gm, is compared with two morphometric studies on Silurid fishes and reveals some original features concerning the increase of the surface area of the receptor epithelium. The olfactory organ is meant to function in water; its isolation from the aerial environment is carried out by closing the apertures with edema linked to the hypothyroid and cholinergic crisis during the starvation stage; it represents an adaptation to the life in a special environment. This study does not support the assimilation of the posterior intrabuccal opening to a choana, nor the presence of a functional vomeronasal organ. The olfactory nerve shows a definite degree of organization, but it was not possible to recognize any vomeronasal nerve linked with the former. The histological organization of the bulbar relay is of a primitive type; it was impossible to locate an accessory olfactory bulb corresponding to a functional vomeronasal organ, the presence and the innervation of which by the nervus terminalis is discussed.
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PMID:Functional anatomy of the peripheral olfactory system of the African lungfish Protopterus annectens Owen: macroscopic, microscopic, and morphometric aspects. 671 60

Fifty-five eating-disordered women and 16 normal controls participated in this study to determine whether olfactory function is altered in patients with food-restricting anorexia, anorexia with bulimic features, and bulimia nervosa. Olfactory function was assessed using the University of Pennsylvania Smell Identification Test and by determining phenyl ethyl alcohol odor detection thresholds. Only the very low-weight anorexics showed impairments in their identification and detection of odors. This group's olfactory function did not improve from admission to discharge despite significant weight gain. Although, overall, smoking had only a minor influence on olfactory function, the very low-weight anorexic smokers had the lowest scores of all subjects. Since higher-weight anorexics did not show such impairments, the results suggest that the severe and prolonged starvation experienced by the very low-weight anorexics caused or contributed to intractable deficits in the olfactory system and that these deficits are compounded by smoking.
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PMID:Olfactory dysfunction in anorexia and bulimia nervosa. 767 Apr 45

The autosomal recessive lethal anorexia mutation in mice (anx/anx) causes starvation in preweanlings. In addition, this murine neurodevelopmental mutant shows other distinct phenotypic characteristics and dysfunctional behaviors. Previous studies strongly suggested that the mutation results in elevated serotonergic stimulation, because these traits are characteristic of such overstimulation and because brain serotonin is believed to have an inhibitory effect on feeding behavior. In this report, we show extensive serotonergic hyperinnervation in normal target fields (hippocampus, cortex, olfactory bulb and cerebellum) of mutant mice. Despite the extensive hyperinnervation, the normal laminar organization of the brain was retained. The specificity of the mutation to the serotonergic system was confirmed by demonstration of normal catecholaminergic innervation in the central nervous system (CNS), and this specificity was especially striking in a common target field, the cerebellum. Serotonergic hyperinnervation in these mutant preweanling mice may represent the underlying etiology of increased serotonergic stimulation which leads to anorexic starvation, abnormal behavior, and premature death.
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PMID:Drastic and selective hyperinnervation of central serotonergic neurons in a lethal neurodevelopmental mouse mutant, Anorexia (anx). 798 37

Caenorhabditis elegans uses a variety of attractive olfactory cues to detect food. We show here that the responses to olfactory cues are regulated in a dynamic way by behavioral context and the animal's previous experience. Prolonged exposure to an odorant leads to a decreased response to that odorant, a form of behavioral plasticity called olfactory adaptation. We show that starvation can increase the extent of olfactory adaptation to the odorant benzaldehyde; this effect of starvation persists for several hours after the animals have been returned to food. The effect of starvation is antagonized by exogenous serotonin, which induces many of the same behavioral responses in C. elegans as are induced by food. Starvation also inhibits recovery from adaptation to a different odorant, 2-methylpyrazine, thus enhancing olfactory memory. In addition to its effects on adaptation, starvation modulates olfactory discrimination in C. elegans; starved animals discriminate more classes of odorants than fed animals. Increased olfactory discrimination is also seen in the adaptation-defective mutant adp-1 (ky20). These various forms of behavioral plasticity enhance the ability of starved animals to respond to novel, potentially informative odorants.
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PMID:Environmental signals modulate olfactory acuity, discrimination, and memory in Caenorhabditis elegans. 1045 62

Hormonal regulation of a major 20 kDa protein of hamster exorbital lacrimal gland (LG) was studied by SDS-PAGE profile analysis and the purified protein's antisera was used to screen tissues of hamster and other species for crossreacting proteins. This protein was seen in female LG but not in males and late-pregnant or hCG-treated females. Low estrogen state in females after gonadectomy, prolonged light-deprivation, prolonged starvation or lactation increased its level several folds to approximately 20% of LG soluble proteins and similar levels were induced in males after gonadectomy (low androgen state). However, light-deprivation or melatonin treatment-induced low androgen state in males had no effect. In gonadectomized hamsters, this LG protein was obliterated on treatment with androgens, estrogens or thyroid hormones. Only estrogen inhibition of LG 20 kDa was prevented by simultaneous tamoxifen administration. Simultaneous treatment of gonadectomized hamsters with gonadotrophins and estrogen/androgen did not prevent the LG 20 kDa protein's inhibition. Relative potencies of estrogens (3.6 microg daily dose) were: estradiol-17beta approximately diethylstilbestrol > estrone > estradiol-17alpha, while estriol and chlorotrianisene had no effect. Dexamethasone, progesterone, prolactin, hypothyroid state or adrenalectomy had no effect on LG 20 kDa expression. Western blot studies confirmed the marked repression of LG 20 kDa by estrogen androgen and thyroid hormone and detected the protein in tears of females and gonadectomized hamsters but not in males. Interestingly, among other tissues tested, crossreaction was only seen with the estrogen-repressed 24 and 20.5 kDa major male-specific secretory proteins of hamster submandibular glands (SMG) which were previously reported by us. This strongly indicated that the LG and SMG proteins are products of the same or closely related genes. A possible role for these hamster sex-specific LG and SMG major secretory proteins in olfactory communication is suggested.
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PMID:Hormonal effects on hamster lacrimal gland female-specific major 20 kDa secretory protein and its immunological similarity with submandibular gland major male-specific proteins. 1062 3

Olfactory learning and memory processes in Drosophila have been well investigated with aversive conditioning, but appetitive conditioning has rarely been documented. Here, we report for the first time individual olfactory conditioning of proboscis activity in restrained Drosophila melanogaster. The protocol was adapted from those developed for proboscis extension conditioning in the honeybee Apis mellifera. After establishing a scale of small proboscis movements necessary to characterize responses to olfactory stimulation, we applied Pavlovian conditioning, with five trials consisting of paired presentation of a banana odour and a sucrose reward. Drosophila showed conditioned proboscis activity to the odour, with a twofold increase of percentage of responses after the first trial. No change occurred in flies experiencing unpaired presentations of the stimuli, confirming an associative basis for this form of olfactory learning. The adenylyl cyclase mutant rutabaga did not exhibit learning in this paradigm. This protocol generated at least a short-term memory of 15 min, but no significant associative memory was detected at 1 h. We also showed that learning performance was dependent on food motivation, by comparing flies subjected to different starvation regimes.
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PMID:Olfactory conditioning of proboscis activity in Drosophila melanogaster. 1696 95

We tested the hypothesis that, in the amphibian Xenopus laevis, cocaine- and amphetamine-regulated transcript peptide (CARTp) not only has widespread actions in the brain but also acts as a local factor in endocrine pituitary cells and/or is neurohemally secreted into the circulation to control peripheral targets. CARTp-immunoreactive cells occur in the olfactory bulb, nucleus accumbens, amygdala, septum, striatum, nucleus of Bellonci, ventrolateral nucleus, central thalamic nucleus, preoptic nuclei, and suprachiasmatic nucleus, and particularly in the medial pallium, ventromedial nucleus, hypothalamus, Edinger-Westphal nucleus, optic tectum, raphe nuclei, central gray, nucleus of the solitary tract, and spinal cord. From the hypothalamic magnocellular nucleus, CARTp-containing axons run to the neurohemal median eminence, and to the neural pituitary lobe to form neurohemal terminals, as shown by immunoelectron microscopy. Starvation increases the number of CARTp-cells in the optic tectum by 46% but has no effect on such cells in the torus semicircularis. CARTp does not affect in vitro release of alpha-melanophore-stimulating hormone from pituitary melanotrope cells. Our results support the hypothesis that in X. laevis, CARTp not only has multiple and not exclusively feeding-related actions in the brain but is also secreted as a neurohormone 1) into the portal system to control endocrine targets in the pituitary distal lobe and 2) from neurohemal axon terminals in the neural pituitary lobe to act peripherally. The differences in CARTp distribution between X. laevis and Rana esculenta may be related to different environmental and physiological conditions such as feeding, sensory information processing, and locomotion.
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PMID:Brain distribution and evidence for both central and neurohormonal actions of cocaine- and amphetamine-regulated transcript peptide in Xenopus laevis. 1822 Feb 55


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