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A unique profile of neurochemical events is proposed to occur in the diencephalon which is contingent upon the nutrient status of the animal. In this first of a series of investigations, we selected the lateral hypothalamus (LH) in order to determine its specific resting profile of monoaminergic neurotransmitters and their principal metabolites. The neuronal pattern of activity was studied during sated and fasted conditions as well as during a local glucoprivic challenge to the LH. After permanent guide cannulae for push-pull perfusion were implanted in female Sprague-Dawley rats, the LH was perfused repeatedly with an artificial CSF, at a rate of 20 microliters/min, in order to collect a series of 5.0 min samples. Aliquots of each perfusate were assayed directly using a high performance liquid chromatography system with electrochemical detection (HPLC-EC) for pg/microliter concentrations of norepinephrine (NE), dopamine (DA) and serotonin (5-HT). In comparison to the basal levels of amines during the sated condition, when the rat was food-deprived for 20-22 hr, the release of NE, DA, and 5-HT was significantly lower than that observed under the sated condition. Further, the turnover of NE in the LH was concurrently attenuated as reflected by the lower levels of MHPG in the perfusate, thus demonstrating the modification in catecholamine activity produced in the LH by the condition of hunger. When either 10 micrograms/microliters 2-deoxy-D-glucose (2-DG) or 4.0 mU/microliter insulin was incorporated into the CSF perfused in the LH, the efflux of DA was significantly enhanced independent of the state of satiation. In addition, the proportion of both NE and DA to 5-HT was likewise increased by either of these centrally acting substances, while the turnover of 5-HT was enhanced and NE and DA turnovers were reduced. Perfusion of 2-DG in the LH of the fasted rat caused a significant reduction in catecholamine turnover in terms of MHPG/NE, VMA/NE, DOPAC/DA and HVA/DA ratios. Moreover, 2-DG increased NE/5-HT while lowering the NE/DA ratio, and enhanced simultaneously the 5-HTOL/5-HT ratio. In the sated rat, 2-DG attenuated the release of 5-HT from the animal's LH, whereas insulin caused a shift in the proportions of NE/5-HT and DA/5-HT. Further, the peptide served to reduced the efflux of 5-HT, enhanced the turnover of 5-HT while diminishing DA turnover, and shifted the metabolism of NE from MHPG to VMA.(ABSTRACT TRUNCATED AT 400 WORDS)
R D Myers, and
J M Peinado, and
F J Miñano
January 1987,
The American journal of physiology,
R D Myers, and
J M Peinado, and
F J Miñano
May 1979,
The American journal of physiology,
R D Myers, and
J M Peinado, and
F J Miñano
January 1976,
Brain research bulletin,
R D Myers, and
J M Peinado, and
F J Miñano
October 1976,
Pharmacology, biochemistry, and behavior,
R D Myers, and
J M Peinado, and
F J Miñano
October 1972,
Gastroenterology,
R D Myers, and
J M Peinado, and
F J Miñano
December 1993,
Brain research,
R D Myers, and
J M Peinado, and
F J Miñano
December 1985,
Brain research,
R D Myers, and
J M Peinado, and
F J Miñano
December 1964,
Endocrinologia japonica,
R D Myers, and
J M Peinado, and
F J Miñano
March 1979,
Physiology & behavior,
R D Myers, and
J M Peinado, and
F J Miñano
June 2001,
Bulletin of experimental biology and medicine,
