Neurochemical Changes after Imbalanced Diets Suggest a Brain Circuit Mediating Anorectic Responses to Amino Acid Deficiency in Rats

Manuscript received 24 March 1997. Initial reviews completed 13 May 1997. Revision accepted 15 December 1997.

Dorothy W. Gietzen^{*, **,} , Lesa F. Erecius^*, and Quinton R. Rogers^{, **}

Departments of ^* Anatomy, Physiology and Cell Biology,  Department of Molecular Biosciences, School of Veterinary Medicine, and ^** Food Intake Laboratory, University of California Davis, Davis, CA 95616

Amino acid-imbalanced (IMB) diets induce an acute amino acid deficiency and hypophagic responses in most animals. The neural circuits underlying these responses are unknown. To ascertain potential neural circuits involved in the recognition of IMB, we measured the concentrations of norepinephrine, dopamine, serotonin, their metabolites and 20 amino acids in 14 rat brain areas in three studies. Rats were prefed a basal diet with L-amino acids as the protein source for at least 1 wk. For the experiments, either threonine or isoleucine IMB diet was offered for 2.5 or 3.5 h. Brains were taken before (using a mildly IMB diet) or after (using moderately or severely IMB diet) food intake was significantly (P < 0.05) depressed. Brain areas were dissected and analyzed for monoamines, metabolites and amino acids. Only in the anterior piriform cortex (APC), a brain area that may contain the amino acid chemosensor, was the limiting amino acid lower in IMB groups than in controls across all of the experiments. Before the onset of the anorectic response to the IMB diets, monoaminergic activity was affected in areas that have recognized monosynaptic connections with the APC. We propose a circuit for the neural responses in the initial recognition of acute amino acid deprivation that begins with activation of the APC and includes areas in the hindbrain and hypothalamus. After a significant hypophagic response, serotonergic indicators were altered in areas of the taste pathway and the limbic system. These results suggest that different circuits mediate the initial recognition and secondary conditioned responses to IMB diets.

The Journal of Nutrition Vol. 128 No. 4 April 1998, pp. 771-781
Copyright ©1998 by the American Society for Nutritional Sciences

This article has been cited by other articles:

				F. M. Lartey and R. E. Austic Phenylalanine hydroxylase activity and expression in chicks subjected to phenylalanine imbalance or phenylalanine toxicity Poult. Sci., April 1, 2009; 88(4): 774 - 783. [Abstract] [Full Text] [PDF]

				F. M. Lartey and R. E. Austic Phenylalanine Requirement, Imbalance, and Dietary Excess in One-Week-Old Chicks: Growth and Phenylalanine Hydroxylase Activity Poult. Sci., February 1, 2008; 87(2): 291 - 297. [Abstract] [Full Text] [PDF]

				D. W. Gietzen, C. M. Ross, S. Hao, and J. W. Sharp Phosphorylation of eIF2{alpha} Is Involved in the Signaling of Indispensable Amino Acid Deficiency in the Anterior Piriform Cortex of the Brain in Rats J. Nutr., April 1, 2004; 134(4): 717 - 723. [Abstract] [Full Text] [PDF]

				A. Blais, J.-F. Huneau, L. J. Magrum, T. J. Koehnle, J. W. Sharp, D. Tome, and D. W. Gietzen Threonine Deprivation Rapidly Activates the System A Amino Acid Transporter in Primary Cultures of Rat Neurons from the Essential Amino Acid Sensor in the Anterior Piriform Cortex J. Nutr., July 1, 2003; 133(7): 2156 - 2164. [Abstract] [Full Text] [PDF]

				T. J. Koehnle, M. C. Russell, and D. W. Gietzen Rats Rapidly Reject Diets Deficient in Essential Amino Acids J. Nutr., July 1, 2003; 133(7): 2331 - 2335. [Abstract] [Full Text] [PDF]

				M. Smriga, M. Kameishi, H. Uneyama, and K. Torii Dietary L-Lysine Deficiency Increases Stress-Induced Anxiety and Fecal Excretion in Rats J. Nutr., December 1, 2002; 132(12): 3744 - 3746. [Abstract] [Full Text] [PDF]

				D. W. Gietzen and L. J. Magrum Molecular Mechanisms in the Brain Involved in the Anorexia of Branched-Chain Amino Acid Deficiency J. Nutr., March 1, 2001; 131(3): 851S - 855. [Abstract] [Full Text]

				J.-H. Yuan, A. J. Davis, and R. E. Austic Temporal Response of Hepatic Threonine Dehydrogenase in Chickens to the Initial Consumption of a Threonine-Imbalanced Diet J. Nutr., November 1, 2000; 130(11): 2746 - 2752. [Abstract] [Full Text] [PDF]

				P. C. Even, V. Rolland, S. Feurte, G. Fromentin, S. Roseau, S. Nicolaidis, and D. Tome Postprandial metabolism and aversive response in rats fed a threonine-devoid diet Am J Physiol Regulatory Integrative Comp Physiol, July 1, 2000; 279(1): R248 - R254. [Abstract] [Full Text] [PDF]

				M. Smriga, M. Mori, and K. Torii Circadian Release of Hypothalamic Norepinephrine in Rats In Vivo Is Depressed during Early L-Lysine Deficiency J. Nutr., June 1, 2000; 130(6): 1641 - 1643. [Abstract] [Full Text]

				C. X. Wang, L. F. Erecius, J. L. Beverly III, and D. W. Gietzen Essential Amino Acids Affect Interstitial Dopamine Metabolites in the Anterior Piriform Cortex of Rats J. Nutr., September 1, 1999; 129(9): 1742 - 1745. [Abstract] [Full Text]

				L. L. Bellinger, J. F. Evans, C. M. Tillberg, and D. W. Gietzen Effects of dorsomedial hypothalamic nuclei lesions on intake of an imbalanced amino acid diet Am J Physiol Regulatory Integrative Comp Physiol, July 1, 1999; 277(1): R250 - R262. [Abstract] [Full Text] [PDF]

				L. L. Bellinger, J. F. Evans, and D. W. Gietzen Dorsomedial Hypothalamic Lesions Alter Intake of an Imbalanced Amino Acid Diet in Rats J. Nutr., July 1, 1998; 128(7): 1213 - 1217. [Abstract] [Full Text] [PDF]