title: Effects of hyper- and hypothyroidism on acetylcholinesterase, (Na(+), K (+))- and Mg ( 2+ )-ATPase activities of adult rat hypothalamus and cerebellum.
abstract: Thyroid hormones (THs) are recognized as key metabolic hormones, and the metabolic rate increases in hyperthyroidism, while it decreases in hypothyroidism. The aim of this work was to investigate how changes in metabolism induced by THs could affect the activities of acetylcholinesterase (AChE), (Na(+), K(+))- and Mg(2+)-ATPase in the hypothalamus and the cerebellum of adult rats. Hyperthyroidism was induced by subcutaneous administration of thyroxine (25 microg/100 g body weight) once daily for 14 days, while hypothyroidism was induced by oral administration of propylthiouracil (0.05%) for 21 days. All enzyme activities were evaluated spectrophotometrically in the homogenated brain regions of 10 three-animal pools. Neither hyper-, nor hypothyroidism had any effect on the examined hypothalamic enzyme activities. In the cerebellum, hyperthyroidism provoked a significant decrease in both the AChE (-23%, p < 0.001) and the Na(+), K(+)-ATPase activities (-26%, p < 0.001). Moreover, hypothyroidism had a similar effect on the examined enzyme activities: AChE (-17%, p < 0.001) and Na(+), K(+)-ATPase (-27%, p < 0.001). Mg(2+)-ATPase activity was found unaltered in both the hyper- and the hypothyroid brain regions.
  
  
  CONCLUSIONS
  neither hyper-, nor hypothyroidism had any effect on the examined hypothalamic enzyme activities. In the cerebellum, hyperthyroidism provoked a significant decrease in both the AChE and the Na(+), K(+)-ATPase activities. The decreased (by the THs) Na(+), K(+)-ATPase activities may increase the synaptic acetylcholine release, and thus, could result in a decrease in the cerebellar AChE activity. Moreover, the above TH-induced changes may affect the monoamine neurotransmitter systems.
authors.affiliation: Department of Experimental Pharmacology, Medical School, University of Athens, Athens, Greece.
authors.forename: Haris
authors.initials: H
authors.lastname: Carageorgiou
authors.forename: Constantinos
authors.initials: C
authors.lastname: Pantos
authors.forename: Apostolos
authors.initials: A
authors.lastname: Zarros
authors.forename: Vasileios
authors.initials: V
authors.lastname: Stolakis
authors.forename: Iordanis
authors.initials: I
authors.lastname: Mourouzis
authors.forename: Dennis
authors.initials: D
authors.lastname: Cokkinos
authors.forename: Stylianos
authors.initials: S
authors.lastname: Tsakiris
mesh_terms: D000110:Acetylcholinesterase / Q000378:metabolism; D000251:Adenosine Triphosphatases / Q000378:metabolism; D000367:Age Factors; D000818:Animals; D002531:Cerebellum / Q000201:enzymology*; D006867:Hydrolases / Q000378:metabolism*; D006980:Hyperthyroidism / Q000378:metabolism*; D007031:Hypothalamus / Q000201:enzymology*; D007037:Hypothyroidism / Q000378:metabolism*; D008297:Male; D051381:Rats; D017208:Rats, Wistar; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism
chemical_list: D006867:Hydrolases; D000110:Acetylcholinesterase; D000251:Adenosine Triphosphatases; C035123:magnesium sodium ATPase; D000254:Sodium-Potassium-Exchanging ATPase