Localization and role of serotonin in the adrenal gland of Podarcis sicula (Reptilia, Lacertidae).
The occurrence of serotonin (5-hydroxytryptamine; 5-HT) in the chromaffin cells of Podarcis sicula adrenal gland was demonstrated by immunocytochemical techniques: ABC and immunogold methods. At LM and EM levels, antiserum against 5-HT revealed serotonin immunoreactivity prevalently in noradrenalin (NA) cells, on and around secretory vesicles; adrenalin (A) cells appeared scarcely stained. The role of serotonin in the regulation of adrenal gland activity was studied in vivo using LM and EM techniques coupled to a specific radioimmunoassay for adrenocorticotropic hormone (ACTH) and corticosterone. 5-HT (0.7 mg/100 g body wt)/day for 4 days increased ACTH and corticosterone release; at LM and EM level clear signs of stimulation in the steroidogenic tissue were observed, as evidenced by the variations of lipid/cytoplasm ratio. In the chromaffin tissue, LM observations evidenced a variation of the numeric NA/A cell ratio; at EM level, chromaffin tissue showed intermediate cells with A, NA, and very clear granules with granular elements. The occurrence of these cells might be the result of a process of resynthesis following serotonin-stimulated catecholamine release. These data suggested that serotonin might be involved in the modulation of Podarcis pituitary-adrenal axis, and act as a paracrine factor to modulate corticosteroid production.
Capaldo
Anna
A
Department of Evolutionary and Comparative Biology, University Federico II, Via Mezzocannone 8, Naples 80134, Italy. capaldo@unina.it
Laforgia
Vincenza
V
Sciarrillo
Rosaria
R
Valiante
Salvatore
S
Gay
Flaminia
F
Varano
Lorenzo
L
D000311:Adrenal Glands / Q000187:drug effects / Q000378:metabolism / Q000502:physiology* / Q000648:ultrastructure; D000324:Adrenocorticotropic Hormone / Q000097:blood; D000818:Animals; D003345:Corticosterone / Q000097:blood; D004837:Epinephrine / Q000378:metabolism; D007150:Immunohistochemistry; D008116:Lizards / Q000033:anatomy & histology / Q000378:metabolism / Q000502:physiology*; D008854:Microscopy, Electron; D016253:Microscopy, Immunoelectron; D009638:Norepinephrine / Q000378:metabolism; D011863:Radioimmunoassay; D012701:Serotonin / Q000378:metabolism / Q000494:pharmacology / Q000502:physiology*; D014018:Tissue Distribution
D012701:Serotonin; D000324:Adrenocorticotropic Hormone; D003345:Corticosterone; D009638:Norepinephrine; D004837:Epinephrine