Abstract
Regional and dietary-induced changes in hypothalamic extracellular amino acid concentrations were examined. Microdialysis probes were simultaneously implanted in the hypothalamic paraventricular nucleus (PVN) and the lateral hypothalamus (LH) of anesthetized rats and perfused at a rate of 2 μl/min. Dialysates were collected every 20 min for l h prior to gavage of a balanced amino acid mixture (0.85 g patterned after 1 g of chicken egg albumin) and then every 20 min for 3 h after treatment. Tail vein blood samples were also collected. Marked changes in plasma levels of most amino acids were evident immediately following the amino acid gavage. In the PVN, concentrations of isoleucine, leucine, methionine and valine all increased within 40 min, whereas significant decreases in glutamine, histidine and taurine were observed in the LH. In a separate study, PVN extracellular amino acid concentrations were examined in awake, freely-behaving rats following gavage of equicaloric loads of a balanced amino acid mixture, glucose (0.89 g) or water. Dialysate levels of glutamate, isoleucine, leucine, methionine, threonine, tyrosine and valine showed reliable increases after amino acid treatment, although the overall time course of these effects differed somewhat. The amino acid profile of the PVN was, in general, unaffected by glucose administration. These findings suggest that specific brain regions may respond uniquely to amino acid ingestion and further imply that dietary composition may influence the amino acid profiles of the extracellular fluid in brain.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.