Hepatic poly(ADP-ribose) polymerase activity in rat is controlled by thyroid hormones.
The in vivo effect of the thyroidal state on poly(ADP-ribose) polymerase activity was investigated in eu- and hypothyroid rats after treatment with L-triiodothyronine. Untreated hypothyroids showed an increased basal rate of the enzyme. The treatment of both eu- and hypothyroid rats with L-triiodothyronine induced a prompt drop of the endogenous activity not due to a reduction of the catalytic protein. This decrease well evident 1 h after treatment was transient, returning to controls values within 8 h. In isolated liver nuclei from euthyroids the in vitro exposure to increasing L-triiodothyronine concentrations from 10(-18) to 10(-6) M resulted in a progressive inhibition of the enzyme. This loss in activity was not derived from a reduction of the total level of the catalytic protein. The pretreatment with the antagonist amiodarone suppressed the hormone effect, suggesting that nuclear receptors could mediate poly(ADP-ribose) polymerase activity.
Cesarone
C F
CF
Institute of General Physiology, University of Genoa, Italy.
Scarabelli
L
L
Giannoni
P
P
Orunesu
M
M
D000638:Amiodarone / Q000494:pharmacology; D000818:Animals; D002467:Cell Nucleus / Q000187:drug effects / Q000201:enzymology; D006706:Homeostasis; D007037:Hypothyroidism / Q000201:enzymology*; D007700:Kinetics; D008099:Liver / Q000187:drug effects / Q000201:enzymology*; D008297:Male; D011065:Poly(ADP-ribose) Polymerases / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D011988:Receptors, Thyroid Hormone / Q000502:physiology; D012016:Reference Values; D013961:Thyroid Gland / Q000502:physiology*; D013965:Thyroidectomy; D013997:Time Factors; D014284:Triiodothyronine / Q000494:pharmacology*
D011988:Receptors, Thyroid Hormone; D014284:Triiodothyronine; D011065:Poly(ADP-ribose) Polymerases; D000638:Amiodarone