Capaldo Anna, Laforgia Vincenza, Sciarrillo Rosaria, De Falco Maria, Valiante Salvatore, Gay Flaminia, Virgilio Francesca, Varano Lorenzo
Department of Evolutive and Comparative Biology, University of Naples "Federico II," 80134, Naples, Italy.
Gen Comp Endocrinol. 2004 Jan 1;135(1):17-24. doi: 10.1016/j.ygcen.2003.08.001.
The effects of dopamine administration on the adrenal gland of a lizard, Podarcis sicula, are described. Dopamine (0.7mg/100g body wt/day for 4 consecutive days) raised plasma ACTH and corticosterone levels (ACTH: from the basal level of 4.40+/-0.05-7.30+/-0.08pg/ml 24h after the fourth dopamine injection; corticosterone: from 3.59+/-0.03ng/ml in untreated lizards to 7.40+/-0.05ng/ml 24h after the fourth dopamine injection), showing a stimulatory effect on the pituitary-interrenal axis activity. In the chromaffin tissue dopamine apparently enhanced the activity of PNMT enzyme; in fact a strong raise in the number of adrenaline cells and a decrease in the number of noradrenaline cells were observed, decreasing the numeric NA/A cell ratio, from 1.4/1 of control specimens to 0.5/1 24h after the fourth dopamine injection. At EM level, chromaffin cells contained both NA and A granules, as well as very clear granules (CG); CG granules showed granular elements ranging between 340 and 347A in diameter. These cells might be the morphological expression of a process of catecholamine resynthesis, due to a possible increase in catecholamine release, following exposure to dopamine.
