Increased Intracellular Calcium in Rat Anterior Piriform Cortex in Response to Threonine After Threonine Deprivation

1999 ◽  
Vol 81 (3) ◽  
pp. 1147-1149 ◽  
Author(s):  
Linda J. Magrum ◽  
M. Anne Hickman ◽  
Dorothy W. Gietzen
Keyword(s):  
Amino Acid ◽  
Intracellular Calcium ◽  
Piriform Cortex ◽  
Anterior Piriform Cortex ◽  
Enhanced Activity ◽  
Sustained Increase

Increased intracellular calcium in rat anterior piriform cortex in response to threonine after threonine deprivation The anterior piriform cortex (APC) may serve as the chemosensor for amino acid (AA) deficiency in rats. To investigate the mechanism by which the APC recognizes a limiting indispensable AA (IAA), we examined changes in intracellular calcium ([Ca2+]i) in APC slices after culture in medium with or without threonine (Thr) or lysine (Lys). The addition of 1 or 10 mM Thr to slices previously incubated in Thr-devoid medium resulted in a significant and sustained increase in [Ca2+]i compared to control slices; an effect not seen when isoleucine, another IAA, was added. Similar results were seen when lysine, but not threonine, was added to slices incubated in lysine-devoid medium. The rise in [Ca2+]iresulting from the addition of the limiting IAA to deficient slices may be linked to enhanced activity of the appropriate AA transporter. This is suggested by preliminary findings that serine, a small neutral AA that uses the same transporter as threonine, gave rise to an enhanced response in the Thr-deficient slice.

Indispensable amino acid deficiency and increased seizure susceptibility in rats

1996 ◽  
Vol 271 (1) ◽  
pp. R18-R24
Author(s):  
D. W. Gietzen ◽  
K. D. Dixon ◽  
B. G. Truong ◽  
A. C. Jones ◽  
J. A. Barrett ◽  
...  
Keyword(s):  
Amino Acid ◽  
Brain Area ◽  
Piriform Cortex ◽  
Experimental Models ◽  
Energy Deficit ◽  
Seizure Susceptibility ◽  
Anterior Piriform Cortex ◽  
Indispensable Amino Acid ◽  
Seizure Models ◽  
Increased Susceptibility

Repeated subthreshold stimulation of limbic brain areas increases seizure susceptibility in experimental models of epilepsy. In addition, acute dietary indispensable amino acid (IAA) deficiency activates the anterior piriform cortex (APC), a seizure-prone limbic brain area in the rat. Based on these two findings, we hypothesized that activation of the APC by chronic exposure to IAA-deficient diets might increase seizure susceptibility. Several nonessential amino acid neurotransmitters are important in seizures, but deficiencies of nontransmitter IAAs have not been well studied in seizure models. In four trials, we made injections of pentylenetetrazole intraperitoneally or of bicuculline into the APC in histidine-, isoleucine-, or threonine-deficient rats and controls. Increased susceptibility to seizures in the deficient animals was observed as increased severity of the seizures, decreased threshold for the dose of the chemostimulant and time to seizure, or a combination thereof. Pair-fed controls showed that this effect was not due to an energy deficit. This novel but robust finding suggests that IAA deficiency may increase vulnerability to seizures by repeated activation of the APC.

scholarly journals Diets Deficient in Indispensable Amino Acids Rapidly Decrease the Concentration of the Limiting Amino Acid in the Anterior Piriform Cortex of Rats

2004 ◽  
Vol 134 (9) ◽  
pp. 2365-2371 ◽  
Author(s):  
Thomas J. Koehnle ◽  
Matthew C. Russell ◽  
Andrew S. Morin ◽  
Lesa F. Erecius ◽  
Dorothy W. Gietzen
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Piriform Cortex ◽  
Anterior Piriform Cortex ◽  
Indispensable Amino Acids ◽  
Limiting Amino Acid
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