Effects of dopamine on the adrenal gland of Podarcis sicula (Reptilia, Lacertidae).
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.
Capaldo
Anna
A
Department of Evolutive and Comparative Biology, University of Naples "Federico II," 80134, Naples, Italy. nevotta16@libero.it
Laforgia
Vincenza
V
Sciarrillo
Rosaria
R
De Falco
Maria
M
Valiante
Salvatore
S
Gay
Flaminia
F
Virgilio
Francesca
F
Varano
Lorenzo
L
D000311:Adrenal Glands / Q000187:drug effects* / Q000378:metabolism / Q000648:ultrastructure; D000324:Adrenocorticotropic Hormone / Q000378:metabolism; D000818:Animals; D004298:Dopamine / Q000494:pharmacology*; D050356:Lipid Metabolism; D008854:Microscopy, Electron; D012104:Reptiles
D000324:Adrenocorticotropic Hormone; D004298:Dopamine