ZfN: Search Results

1	Author	Stylianos Tsakiris	Requires cookie*
	Title	Effects of L-Phenylalanine on Acetylcholinesterase, (Na+,K+)-ATPase and Mg2+-ATPase Activities in Adult Rat Whole Brain and Frontal Cortex
	Abstract	The effect of different L-phenylalanine (Phe) concentrations (0.12-12.1 m M) on acetylcho linesterase (AChE), (Na+,K+)-ATPase and Mg2+-ATPase activities was investigated in ho-mogenates of adult rat whole brain and frontal cortex at 37 °C. AChE, (Na+,K+)-ATPase and Mg2+-ATPase activities were determined after preincubation with Phe. AChE activity in both tissues showed a decrease up to 18% (p<0.01) with Phe. Whole brain Na+,K+-ATPase was stimulated by 30-35% (p<0.01) with high Phe concentrations, while frontal cortex Na+,K+-ATPase was stimulated by 50-55% (pcO.OOl). Mg2+-ATPase activity was increased only in frontal cortex with high Phe concentrations. It is suggested that: a) The inhibitory effect of Phe on brain AChE is not influenced by developmental factors, while the stimulation of Phe on brain Na+,K+-ATPase is indeed affected; b) The stimulatory effect of Phe on rat whole brain Na+,K+-ATPase is decreased with age; c) Na+,K+-ATPase is selectively more stimulated by high Phe concentrations in frontal cortex than in whole brain homogenate; d) High (toxic) Phe concentrations can affect Mg2+-ATPase activity in frontal cortex, but not in whole brain, thus modulating the amount of intracellular Mg2+.
	Reference	Z. Naturforsch. 56c, 132—137 (2001); received September 4/October 4 2000
	Published	2001
	Keywords	Acetylcholinesterase, (Na+, K+)-, Mg2 +-ATPase, L-Phenylalanine
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	TEI-XML for	default:Reihe_C/56/ZNC-2001-56c-0132.pdf
	Identifier	ZNC-2001-56c-0132
	Volume	56

2	Author	Stylianos Tsakiris3, Panagiota Kouniniotou-Krontiri3, KleopatraH. Schulpisb, JohnC. Stavridis3	Requires cookie*
	Title	L-Phenylalanine Effect on Rat Brain Acetylcholinesterase and Na+,K+-ATPase
	Abstract	The effect of different L-phenylalanine (Phe) concentrations (0 .1 -1 2 .1 m M) , on acetylcho linesterase (A C h E) and N a+,K +-ATPase activities of brain homogenate and pure enzymes, was investigated at 37 °C. A C h E and Na+,K +-ATPase activities were determined according to Ellman G. -6 1 3) respectively, after preincubation with Phe. A C h E activity in brain homogenate or in pure eel E.electricus enzyme showed a decrease, which reached up to 18% with concentrations of 0 .9 -1 2 .1 m M . Brain homogenate N a+,K +-A TPase activity showed an increase 1 6 -6 5 % with 0 .2 4 -0 .9 mM of Phe, while an activity increase of 6 0 -6 5 % appeared with 0 .9 -1 2 .1 mM of Phe. Pure en zyme activity (from porcine cerebral cortex) was not affected by high Phe concentrations, while it was increased by low concentrations. The above results suggest: a) A direct effect of Phe on A C h E , b) A direct effect of low Phe concentrations and an indirect effect of high ones on Na+,K +-ATPase.
	Reference	Z. Naturforsch. 53c, 163 (1998); received September 22/D ecem ber 15 1997
	Published	1998
	Keywords	L-Phenylalanine, R at Brain, Acetylcholinesterase, N a+, K +-ATPase, Mg2+-ATPase
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	TEI-XML for	default:Reihe_C/53/ZNC-1998-53c-0163.pdf
	Identifier	ZNC-1998-53c-0163
	Volume	53

3	Author	Stylianos Tsakiris, Panagoula Angelogianni, JohnC. Stavridis	Requires cookie*
	Title	Effect of Aging on the Activities of Acetylcholinesterase, Na+, K+-ATPase and Mg2+-ATPase in Rat Pituitary and Hypothalamus
	Abstract	Acetylcholinesterase (A C h E), N a+, K +-ATPase and Mg2+-A TPase activities were esti mated in homogenised rat pituitary and hypothalamus of 4-and 22-month-old rats. A C hE activity was not altered in the pituitary of aged com pared to adult rats, while it was found decreased by about 40% in the hypothalamus. N a+,K +-A TPase activity remained stable in the hypothalamus, while it was decreased by about 38% in the pituitary. Mg2+-A TPase activ ity remained unchanged in the hypothalamus, but was increased by about 83% in the pitu itary. This pituitary N a+, K +-ATPase inactivation may result in pathological mood and de creased neural excitability and metabolic energy production in aged animals.The age-related alterations of A C h E , Na+, K +-ATPase and Mg2+-A TPase activities may reflect changes in secretion and responses of some hormones of pituitary and hypothalamus.
	Reference	Z. Naturforsch. 53c, 168 (1998); received O ctober 13/O ctober 31 1997
	Published	1998
	Keywords	Aging, R at Pituitary, Rat Hypothalamus, Acetylcholinesterase, N a+, K +-ATPase, Mg2+-ATPase
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	TEI-XML for	default:Reihe_C/53/ZNC-1998-53c-0168.pdf
	Identifier	ZNC-1998-53c-0168
	Volume	53