EFFECTS OF ATROPINE AND CARBACHOL ON 3H-THYMIDINE INCORPORATION INTO DNA OF RAT-THYROID LOBES IN-VITRO

The goal of the study has been to examine the effects of atropine (muscarinic receptor blocker) and of carbachol (muscarinic receptor agonist) on the growth processes in the rat thyroid gland in vitro. Thyroid lobes were incubated for 4 hrs in RPMI 1640 medium + 15% FCS, with an addition of 3H-thymidine (2 mu Ci/ml) and with atropine (10(-11)M, 10(-9)M, 10(-7)M, 10(-5)M and 10(-3)M) or carbachol (10(-11)M, 10(-9)M, 10(-7)M, 10(-5)M and 10(-3)M). Control incubation was conducted without an addition of atropine or carbachol to the medium. Atropine - in all studied concentrations - decreased 3H-thymidine incorporation into DNA of thyroid lobes, whereas carbachol did not affect significantly the rate of 3H-thymidine incorporation (vs. control group). The rates of 3H-thymidine incorporation, following carbachol addition to the medium, were significantly higher than those after atropine in the same molar concentrations. An involvement is suggested of cholinergic regulation in the control of thyroid growth processes.