Hypothyroidism changes adenine nucleotide hydrolysis in synaptosomes from hippocampus and cerebral cortex of rats in different phases of development.
The influence of the thyroid hormones on the normal function of the mammalian central nervous system depends on the brain region and on the developmental stage. Adenine nucleotides and their products also affect the brain function; ATP is an excitatory neurotransmitter, and adenosine has inhibitory effects on neurotransmission. Thus, this study aimed to evaluate the effects of hypothyroidism on the hydrolysis of ATP to adenosine in hippocampal and cortical synaptosomes and blood serum of rats during different phases of development. Rats aged 60 and 420 days old were divided into three groups: control, sham-operated and hypothyroid. Hypothyroidism was induced in these rats by thyroidectomy and methimazole (0.05%) added to their drinking water for 14 days. Neonatal hypothyroidism was induced by adding 0.02% methimazole in the drinking water from day 9 of gestation, and continually until 14 days old. Hypothyroidism increased the AMP hydrolysis in both hippocampus and cerebral cortex synaptosomes of rats in all aged tested. In blood serum, thyroid hormones deficiency increased the AMP hydrolysis in 14-day-old rats and the hydrolysis of ATP, ADP and AMP in 60-day-old rats; however, no alteration was observed in 420-day-old rats. Thus, our results suggest the involvement of the 5'-nucleotidase in synaptic function control in hypothyroidism throughout brain development.
Bruno
Alessandra Nejar
AN
Departamento de Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Avenida Ramiro Barcellos 2600-ANEXO, 90035-003 Porto Alegre, RS, Brazil.
Ricachenevsky
Felipe Klein
FK
Pochmann
Daniela
D
Bonan
Carla Denise
CD
Battastini
Ana Maria Oliveira
AM
Barreto-Chaves
Maria Luiza M
ML
Sarkis
João José Freitas
JJ
D000227:Adenine Nucleotides / Q000378:metabolism*; D000367:Age Factors; D000704:Analysis of Variance; D000818:Animals; D000831:Animals, Newborn; D002540:Cerebral Cortex / Q000166:cytology / Q000254:growth & development / Q000378:metabolism*; D006624:Hippocampus / Q000166:cytology / Q000254:growth & development / Q000378:metabolism*; D006868:Hydrolysis; D007037:Hypothyroidism / Q000139:chemically induced / Q000378:metabolism*; D008297:Male; D008713:Methimazole; D051381:Rats; D017208:Rats, Wistar; D044967:Serum / Q000378:metabolism; D013347:Subcellular Fractions / Q000378:metabolism; D013574:Synaptosomes / Q000378:metabolism*
D000227:Adenine Nucleotides; D008713:Methimazole