Studies of the role of gamma-aminobutyric acid in the hypothalamic control of feed intake in sheep

1985 ◽  
Vol 63 (10) ◽  
pp. 1297-1301 ◽  
Author(s):  
C. L. Girard ◽  
J. R. Seoane ◽  
J. J. Matte
Keyword(s):  
Dose Response ◽  
Feed Intake ◽  
Gaba Receptors ◽  
Response Curve ◽  
Aminobutyric Acid ◽  
Gamma Aminobutyric Acid ◽  
Gaba Antagonists ◽  
Gaba Agonist ◽  
Hypothalamic Control

Fourteen sheep were used to study the role of gamma-aminobutyric acid (GABA) on the hypothalamic control of feed intake. Injections (1 μL) of pentobarbital (262 nmol) into preoptic and paraventricular areas induced feeding in satiated sheep. Injections of GABA into the same loci gave variable results, probably because the neuronal and glial uptake of GABA limits its effects. Muscimol, a GABA agonist with a higher affinity for postsynaptic GABA receptors than GABA, injected at doses from 0 to 0.750 nmol, gave a cubic dose–response curve; the highest feed intake was measured at 0.5 nmol. The response induced by muscimol was blocked by preinjections of two GABA antagonists, picrotoxin and bicuculline, with picrotoxin being more effective than bicuculline. Muscimol responsive loci were identified mainly in the preoptic, paraventricular, and anterior hypothalamus. The data suggests that neurons sensitive to gamma-aminobutyric acid may be implicated in the control of feed intake in sheep.

Effects of intraventricular injections of gamma-aminobutyric acid and related substances on feeding behavior in satiated sheep

1984 ◽  
Vol 62 (10) ◽  
pp. 1296-1299 ◽  
Author(s):  
J. R. Seoane ◽  
F. Dumont ◽  
C. L. Girard ◽  
L. Bédard ◽  
J. J. Matte
Keyword(s):  
Feeding Behavior ◽  
Feed Intake ◽  
Aminobutyric Acid ◽  
Gamma Aminobutyric Acid ◽  
Gaba Agonist ◽  
Lateral Ventricles ◽  
Related Substances ◽  
Intraventricular Injections ◽  
Gaba Antagonist

Feed intake was measured following injections of gamma-aminobutyric acid (GABA), muscimol (a GABA agonist), and picrotoxin (a GABA antagonist) into the lateral ventricles of satiated sheep. Doses ranging from 0.20 to 3200 nmol of GABA did not affect feeding behavior at 15, 30, 60, and 120 min postinjection. A dose of 160 nmol of muscimol induced a marked increase in feeding, comparable to that provoked by an injection of 78 μmol of pentobarbital. Muscimol-induced feeding was blocked effectively by a preinjection of picrotoxin. These observations implicate that neurons sensitive to gamma-aminobutyric acid may be involved in the control of feeding behavior in ruminants.

Role of gamma-aminobutyric acid in regulating feed intake in commercial broilers reared under normal and heat stress conditions.

2019 ◽  
Vol 84 ◽  
pp. 164-175 ◽  
Author(s):  
Karima El-Naggar ◽  
Seham El-Kassas ◽  
Safaa E. Abdo ◽  
Abeer A.K. Kirrella ◽  
Rasha A. Al wakeel
Keyword(s):  
Heat Stress ◽  
Feed Intake ◽  
Stress Conditions ◽  
Aminobutyric Acid ◽  
Gamma Aminobutyric Acid

Topographic studies of the effects of microinjections of muscimol on the hypothalamic control of feed intake in sheep

1986 ◽  
Vol 64 (4) ◽  
pp. 406-410 ◽  
Author(s):  
C. L. Girard ◽  
J. R. Seoane ◽  
J. J. Matte
Keyword(s):  
Feed Intake ◽  
Aminobutyric Acid ◽  
Gamma Aminobutyric Acid ◽  
Anatomical Basis ◽  
Medial Hypothalamus ◽  
Hypothalamic Control ◽  
Feeding Systems

Ten sheep were used to define the anatomical basis for the feeding systems sensitive to gamma-aminobutyric acid, by using intrahypothalamic microinjections of the gamma-aminobutyric acid agonist, muscimol. In satiated sheep, 1 μL of muscimol (0.5 nmol/μL) elicited feeding when injected into paraventricular, ventromedial, and anterior hypothalamic areas. Similar injections into 39 sites tested in 6-h fasted sheep failed to decrease feed intake. The data suggest that neurons sensitive to gamma-aminobutyric acid in medial hypothalamus may be involved in the initiation of feeding.

scholarly journals The role of Ca2+ in the protoveratrine-induced release of γ-aminobutyrate from rat brain slices

1980 ◽  
Vol 190 (2) ◽  
pp. 333-339 ◽  
Author(s):  
M C W Minchin
Keyword(s):  
Cerebral Cortex ◽  
Rat Brain ◽  
Dose Response ◽  
Transmitter Release ◽  
Response Curve ◽  
Brain Slices ◽  
Veratrum Alkaloids ◽  
Similar Dose ◽  
22Na Uptake

1. Protoveratrine A increased the release of gamma-amino[3H]butyrate from small slices of rat cerebral cortex. This effect increased with increasing protoveratrine concentration, reaching a maximum at 100 microM. 2. Removal of Ca2+ from the superfusing medium did not change the increase in release due to 10 microM-protoveratrine; however, the Ca2+ antagonists, compound D-600, La3+, Mn2+, Mg2+ and also high Ca2+ concentration inhibited the effect of the alkaloid, as did procaine. 3. Protoveratrine A increased the uptake of 22Na+ into the slices with a similar dose-response curve to that found for gamma-aminobutyrate release. For the most part, the substances that inhibited protoveratrine-stimulated gamma-aminobutyrate release also inhibited 22Na+ uptake, although the correlation was not perfect. 4. Although extracellular Ca2+ is not required for protoveratrine-induced gamma-aminobutyrate release, an increase in Na+ influx that is susceptible to inhibition by some Ca2+ antagonists does appear to be associated with this phenomenon. However, the possibility remains that changes in the free intracellular Ca2+ concentration may be important for transmitter release induced by depolarizing veratrum alkaloids.

gamma-Aminobutyric acid-induced response in rat dissociated paratracheal ganglion cells

1992 ◽  
Vol 67 (5) ◽  
pp. 1367-1374 ◽  
Author(s):  
S. Itabashi ◽  
K. Aibara ◽  
H. Sasaki ◽  
N. Akaike
Keyword(s):  
Response Curve ◽  
Ganglion Cells ◽  
Aminobutyric Acid ◽  
Equilibrium Potential ◽  
Induced Response ◽  
Dependent Manner ◽  
Gamma Aminobutyric Acid ◽  
Patch Clamp Technique ◽  
Concentration Dependent Manner ◽  
Concentration Response Curve

1. The pharmacologic properties of gamma-aminobutyric acid (GABA)-induced Cl- current (ICl) were studied in the paratracheal ganglion cells freshly dissociated from 7- to 10-day-old rat trachea in a whole-cell recording mode by the use of a conventional patch-clamp technique. 2. GABA- and muscimol-induced currents increased sigmoidally in a concentration-dependent manner, and both currents reversed at approximately -3 mV, which was close to the Cl- equilibrium potential (ECl). 3. Strychnine (STR) at low concentration and bicuculline (BIC) inhibited GABA response competitively, whereas STR at the higher concentrations, benzylpenicillin (PCG), or picrotoxin (PTX) inhibited noncompetitively. Inhibition of GABA response by PCG but not other antagonists was voltage dependent, indicating that PCG acts as a Cl- channel blocker. 4. The concentration-response curve of pentobarbital sodium (PB)-induced ICl was bell shaped. At concentrations higher than 10(-3) M, both the peak and plateau currents decreased, and a transient "hump" current appeared immediately after washing out PB. In the presence of PB, the concentration-response curve of GABA shifted toward left without changing the maximum response. 5. Although diazepam (DZP) at concentration used did not induce a response, it potentiated the GABA response in a concentration-dependent manner between 10(-8) and 10(-6) M. DZP also caused a parallel shift toward left in the concentration-response curve of GABA. 6. PB or DZP further enhanced the GABA response in the presence of the other agent. 7. It is concluded that the properties of GABAA receptors in the paratracheal ganglion cells are essentially similar to those reported in other preparations.

Role of oxygen in the production of human decompression sickness

1987 ◽  
Vol 63 (6) ◽  
pp. 2380-2387 ◽  
Author(s):  
P. K. Weathersby ◽  
B. L. Hart ◽  
E. T. Flynn ◽  
W. F. Walker
Keyword(s):  
Dose Response ◽  
Response Curve ◽  
Decompression Sickness ◽  
Animal Experiments ◽  
Inert Gases ◽  
Relative Risks ◽  
Data Variability ◽  
Increase Risk ◽  
High O2

In the calculation of decompression schedules, it is commonly assumed that only the inert gas needs to be considered; all inspired O2 is ignored. Animal experiments have shown that high O2 can increase risk of serious decompression sickness (DCS). A trial was performed to assess the relative risks of O2 and N2 in human no-decompression dives. Controlled dives (477) of 30- to 240-min duration were performed with subjects breathing mixtures with low (0.21–0.38 ATA) or high (1.0–1.5 ATA) Po2. Depths were chosen by a sequential dose-response format. Only 11 cases of DCS and 18 cases of marginal symptoms were recorded despite exceeding the presently accepted no-decompression limits by greater than 20%. Analysis by maximum likelihood showed a shallow dose-response curve for increasing depth. O2 was estimated to have zero influence on DCS risk, although data variability still allows a slight chance that O2 could be 40% as effective as N2 in producing a risk of DCS. Consideration of only inert gases is thus justified in calculating human decompression tables.

scholarly journals Heterogeneity in expression of functional ionotropic glutamate and GABA receptors in astrocytes across brain regions: insights from the thalamus

2014 ◽  
Vol 369 (1654) ◽  
pp. 20130602 ◽  
Author(s):  
Simon Höft ◽  
Stephanie Griemsmann ◽  
Gerald Seifert ◽  
Christian Steinhäuser
Keyword(s):  
Ampa Receptors ◽  
Indirect Effects ◽  
Gaba Receptors ◽  
Brain Regions ◽  
Aminobutyric Acid ◽  
Gamma Aminobutyric Acid ◽  
Functional Heterogeneity ◽  
Rt Pcr ◽  
Ventrobasal Thalamus ◽  
The Impact

Astrocytes may express ionotropic glutamate and gamma-aminobutyric acid (GABA) receptors, which allow them to sense and to respond to neuronal activity. However, so far the properties of astrocytes have been studied only in a few brain regions. Here, we provide the first detailed receptor analysis of astrocytes in the murine ventrobasal thalamus and compare the properties with those in other regions. To improve voltage-clamp control and avoid indirect effects during drug applications, freshly isolated astrocytes were employed. Two sub-populations of astrocytes were found, expressing or lacking α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors. AMPA receptor-bearing astrocytes displayed a lower Kir current density than cells lacking the receptors. In contrast, all cells expressed GABA A receptors. Single-cell RT-PCR was employed to identify the receptor subunits in thalamic astrocytes. Our findings add to the emerging evidence of functional heterogeneity of astrocytes, the impact of which still remains to be defined.

Changes in gamma-aminobutyric acid and somatostatin in epileptic cortex associated with low-grade gliomas

1992 ◽  
Vol 77 (2) ◽  
pp. 209-216 ◽  
Author(s):  
Michael M. Haglund ◽  
Mitchel S. Berger ◽  
Dennis D. Kunkel ◽  
JoAnn E. Franck ◽  
Saadi Ghatan ◽  
...  
Keyword(s):  
Epileptiform Activity ◽  
Aminobutyric Acid ◽  
Low Grade ◽  
Tumor Infiltration ◽  
Gamma Aminobutyric Acid ◽  
Content Type ◽  
Low Grade Gliomas ◽  
Neuronal Populations ◽  
Significant Difference

✓ The role of specific neuronal populations in epileptic foci was studied by comparing epileptic and nonepileptic cortex removed from patients with low-grade gliomas. Epileptic and nearby (within 1 to 2 cm) nonepileptic temporal lobe neocortex was identified using electrocorticography. Cortical specimens taken from four patients identified as epileptic and nonepileptic were all void of tumor infiltration. Somatostatin- and γ-aminobutyric acid (GABAergic)-immunoreactive neurons were identified and counted. Although there was no significant difference in the overall cell count, the authors found a significant decrease in both somatostatin- and GABAergic-immunoreactive neurons (74% and 51 %, respectively) in the epileptic cortex compared to that in nonepileptic cortex from the same patient. It is suggested that these findings demonstrate changes in neuronal subpopulations that may account for the onset and propagation of epileptiform activity in patients with low-grade gliomas.

Injection of muscimol into posterior hypothalamus blocks stress-induced tachycardia

1989 ◽  
Vol 257 (1) ◽  
pp. R246-R251 ◽  
Author(s):  
M. Lisa ◽  
E. Marmo ◽  
J. H. Wible ◽  
J. A. DiMicco
Keyword(s):  
Gaba Receptors ◽  
Potential Role ◽  
Hypothalamic Nucleus ◽  
Gamma Aminobutyric Acid ◽  
Similar Treatment ◽  
Cardiovascular Changes ◽  
Vehicle Treatment ◽  
Response To Stress ◽  
Posterior Hypothalamic Nucleus

We have previously shown that the physiological and behavioral manifestations of emotional stress are produced when drugs impairing gamma-aminobutyric acid (GABA)-mediated synaptic inhibition are injected into the posterior hypothalamic nucleus in rats [Wible, J.H., Jr., F.C. Luft, and J.A. DiMicco. Am. J. Physiol. 254 (Regulatory Integrative Comp. Physiol. 23): R680-R687, 1988]. The purpose of this study was to assess further the potential role of GABA receptors in this region in the response to stress using muscimol, a GABAA receptor agonist. In six chronically instrumented conscious rats, air stress after vehicle treatment evoked marked and sustained tachycardia (+130 +/- 14 beats/min at +10 min) accompanied by a less dramatic increase in arterial pressure (+14 +/- 3 mmHg). Microinjection of muscimol (10 ng; 88 pmol) at the same posterior hypothalamic site in which GABA blockade causes cardiovascular changes similar to those seen in stress produced a modest depression of cardiovascular function in unstressed animals (-28 +/- 5 beats/min and -6 +/- 3 mmHg). However, similar treatment with muscimol virtually abolished the stress-induced tachycardia in the same rats (+9 +/- 8 beats/min), while having no significant effect on baroreflex-evoked increases in heart rate caused by intravenous infusion of sodium nitroprusside (4 micrograms). These findings support a role for activation of neurons in the posterior nucleus of the hypothalamus in the generation of stress-induced cardiovascular changes and for control of this mechanism by local GABA receptors.

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