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  • American Physiological Society  (5)
  • Grace, M.  (5)
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  • American Physiological Society  (5)
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  • 1
    Online Resource
    Online Resource
    American Physiological Society ; 1994
    In:  American Journal of Physiology-Regulatory, Integrative and Comparative Physiology Vol. 266, No. 6 ( 1994-06-01), p. R1765-R1770
    In: American Journal of Physiology-Regulatory, Integrative and Comparative Physiology, American Physiological Society, Vol. 266, No. 6 ( 1994-06-01), p. R1765-R1770
    Abstract: Intracerebroventricular injection of neuropeptide Y (NPY) has two effects on energy metabolism in addition to increased feeding: decreased brown fat thermogenesis and increased white fat lipoprotein lipase (LPL) enzymatic activity. We hypothesized that the paraventricular nucleus (PVN) of the hypothalamus is the controlling neural site for these responses. We further hypothesized that NPY stimulation at PVN would reduce gene expression for the critical brown fat thermogenic protein, uncoupling protein (UCP), and increase gene expression for the key white fat storage enzyme, LPL. In the first experiment, three groups of rats received injections every 6 h for 24 h (5 injections total) into the PVN:1) NPY (1 micrograms/1 microliters injection) and ad libitum food; 2) NPY (1 micrograms/1 microliters injection) and food restricted to control intake; 3) saline injection (1 microliter) and ad libitum food. Both NPY-treated groups showed significant reductions (P 〈 0.05) in brown fat UCP mRNA levels and marked stimulation of LPL mRNA levels relative to controls. In the second experiment, four groups of seven rats had NPY injected into the PVN:0 (vehicle control); 0.1 microgram; 0.5 microgram; and 1 microgram. Injections were made every 6 h for 24 h. There was a dose-related reduction in UCP mRNA produced by the NPY treatment. NPY treatment increased LPL mRNA, but a smooth dosing effect was not evident. The observation that NPY in the PVN can coordinate more than one component of energy metabolism is significant when considered with many reports of responsiveness of NPY activity in the arcuate nucleus-PVN neural circuit to perturbations of energy balance such as fasting and feeding, diabetes, and genetic obesity.(ABSTRACT TRUNCATED AT 250 WORDS)
    Type of Medium: Online Resource
    ISSN: 0363-6119 , 1522-1490
    Language: English
    Publisher: American Physiological Society
    Publication Date: 1994
    detail.hit.zdb_id: 1477297-8
    SSG: 12
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  • 2
    Online Resource
    Online Resource
    American Physiological Society ; 1996
    In:  American Journal of Physiology-Regulatory, Integrative and Comparative Physiology Vol. 271, No. 1 ( 1996-07-01), p. R217-R221
    In: American Journal of Physiology-Regulatory, Integrative and Comparative Physiology, American Physiological Society, Vol. 271, No. 1 ( 1996-07-01), p. R217-R221
    Abstract: Modulation of feeding behavior by neuropeptide Y (NPY) and opioids is well established, but the possibility that these neural influences provoke specific appetites, NPY for carbohydrate and opioids for fat, has also been considered. In other studies, intake of standard chow after NPY stimulation can be blocked by naloxone, indicating an interaction between these systems in the regulation of feeding. The present experiments examined the nature of NPY-opioid interactions in diet selection. Rats were administered NPY and naloxone concurrently, then chose between high-fat and high-carbohydrate diets. Subcutaneous administration of naloxone (0.01-0.3 mg/kg) potently reduced intake of the preferred diet, but not the nonpreferred diet. A similar pattern of selection was seen in a separate experiment where the same doses of naloxone were administered after 24-h food deprivation. These data support the idea that the opioid system mediates the “rewarding” aspects of feeding.
    Type of Medium: Online Resource
    ISSN: 0363-6119 , 1522-1490
    Language: English
    Publisher: American Physiological Society
    Publication Date: 1996
    detail.hit.zdb_id: 1477297-8
    SSG: 12
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  • 3
    Online Resource
    Online Resource
    American Physiological Society ; 1991
    In:  American Journal of Physiology-Regulatory, Integrative and Comparative Physiology Vol. 260, No. 2 ( 1991-02-01), p. R321-R327
    In: American Journal of Physiology-Regulatory, Integrative and Comparative Physiology, American Physiological Society, Vol. 260, No. 2 ( 1991-02-01), p. R321-R327
    Abstract: Our objective was to find out if central injection of neuropeptide Y (NPY) would alter brown fat thermogenesis and white fat lipoprotein lipase activity. The following three groups of Sprague-Dawley rats received five injections over 24 h into the right lateral ventricle: 1) NPY (5 micrograms/injection) and ad libitum food; 2) NPY (5 micrograms/injection) and food restricted to control intake; 3) saline injection and ad libitum food. The NPY ad libitum-fed group consumed more food than the saline controls or NPY food-restricted animals. Brown fat thermogenic activity, assessed by GDP binding, was decreased relative to saline controls in both NPY-treated groups. White fat lipoprotein lipase activity was greatly increased in both NPY treatment groups compared with saline controls. The NPY effects on brown and white fat were not explained by measures of serum insulin, glucagon, glucose, or other metabolites. In a follow-up experiment, we asked whether food was necessary for expression of the NPY effects. Brown fat mitochondrial GDP binding indicated NPY effect even when no food was ingested. We conclude that intracerebroventricular administration of NPY promotes white fat lipid storage and decreases brown fat thermogenesis in addition to its known effect of stimulating food intake.
    Type of Medium: Online Resource
    ISSN: 0363-6119 , 1522-1490
    Language: English
    Publisher: American Physiological Society
    Publication Date: 1991
    detail.hit.zdb_id: 1477297-8
    SSG: 12
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  • 4
    Online Resource
    Online Resource
    American Physiological Society ; 1995
    In:  American Journal of Physiology-Regulatory, Integrative and Comparative Physiology Vol. 268, No. 1 ( 1995-01-01), p. R248-R252
    In: American Journal of Physiology-Regulatory, Integrative and Comparative Physiology, American Physiological Society, Vol. 268, No. 1 ( 1995-01-01), p. R248-R252
    Abstract: We evaluated the potency of naloxone on intake of normal and sweet chow in food-deprived and schedule-fed rats. We found that naloxone's anorectic potency was dependent on the type of chow presented to the rats and the deprivation schedule utilized to stimulate food intake. In 24-h and 48-h deprived rats, naloxone decreased intake of normal rat chow at doses ranging from 0.3 to 3 mg/kg. In chronically deprived rats (80% of normal body wt), these doses of naloxone failed to decrease intake of normal chow. Rats eating sweet chow ate more when energy deprived and were more sensitive than rats eating normal chow to naloxone-induced limitations in food intake, both in acute and chronic food-deprived groups. Thus naloxone decreased intake of sweet chow much more effectively than normal chow even when rats were chronically food deprived. We also found that an extremely low dose of naloxone (0.03 mg/kg) decreased intake of sweet chow by almost 50% in satiated rats.
    Type of Medium: Online Resource
    ISSN: 0363-6119 , 1522-1490
    Language: English
    Publisher: American Physiological Society
    Publication Date: 1995
    detail.hit.zdb_id: 1477297-8
    SSG: 12
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  • 5
    Online Resource
    Online Resource
    American Physiological Society ; 1991
    In:  American Journal of Physiology-Regulatory, Integrative and Comparative Physiology Vol. 260, No. 3 ( 1991-03-01), p. R546-R552
    In: American Journal of Physiology-Regulatory, Integrative and Comparative Physiology, American Physiological Society, Vol. 260, No. 3 ( 1991-03-01), p. R546-R552
    Abstract: Several neuroactive substances including neuropeptide Y (NPY), muscimol, and norepinephrine (NE) stimulate feeding in satiated rats. In the present study, we observed the behavioral patterns of rats stimulated to eat by food deprivation or by intracerebroventricular (icv) injection of orexigenic agents to explore the hypothesis that such agents produce a behavioral state resembling hunger. Animals that were food deprived for 24 h spent the majority of their time eating (35%), drinking (5%), resting (44%), and moving (13%) when food was available. If food was removed and substituted with a chewable substrate (plastic tube), they chewed on tubes for a brief period (5%) but spent most of their time moving (14%) or resting (77%). In the absence of food or tubes, they briefly moved about the cage (4%) and spent almost all of their time resting (94%). The patterns observed with the orexigenic drugs were different, particularly in the absence of food. NPY-injected rats were more active than deprived rats, spending 22% of their time moving in the presence of food, 47% in the presence of tubes, and 37% in the absence of food or tubes. Rats injected with muscimol demonstrated a marked increase in the time spent chewing and eating. These rats spent 67% of their time eating in the presence of food and chewed 25% of the time in the absence of either food or tubes. NE-injected rats also chewed when tubes were present (17%) or when no food or tubes were present (10%). Lag sequential analysis further documented differences in behavioral patterns amongst the various treatments.(ABSTRACT TRUNCATED AT 250 WORDS)
    Type of Medium: Online Resource
    ISSN: 0363-6119 , 1522-1490
    Language: English
    Publisher: American Physiological Society
    Publication Date: 1991
    detail.hit.zdb_id: 1477297-8
    SSG: 12
    Library Location Call Number Volume/Issue/Year Availability
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