Response of the thyroid gland of the lizard Podarcis sicula to endothelin‐1

Abstract

Although endothelins were originally discovered as peptides with vasoconstrictor activity, recent studies have indicated a number of endothelin (ET) induced hormonal functions in various tissues. We have studied the interaction of ET-1 with thyroid gland of the lizard Podarcis sicula. The effects of ET-1 administration on the plasma levels of the thyroid hormones (T3 and T4) and TSH were stimulatory. Morphological changes in the thyroid after treatment with ET-1 were also detected: the height of the epithelial cells slightly increased and the apical surface acquired microvilli protruding into the follicular lumen. The colloid filled up the lumen and showed a rich peripheral vacuolation. In conclusion, a modulatory role in the control of the reptilian thyroid gland is suggested for ET-1. This is the first report on the interaction of ET-1 with the thyroid gland of reptilian.

Histochemical distribution of endothelin‐converting enzyme subtypes in Podarcis sicula (Squamata, Lacertidae) tissues

“…As previously demonstrated in the lizard Podarcis sicula , ET‐1 plays a role in the secretion of catecholamines and steroids from chromaffin and steroidogenic tissue of the adrenal gland, respectively (De Falco et al. 2001); furthermore, it also influences thyroid gland activity in this reptile (Virgilio et al. 2003) and an ETb receptor is present in P. sicula tissues (De Falco et al.…”

“…In contrast to that from mammals, little information about the ET system is available in lower vertebrates, although ET-1 is known to act on the frog adrenal gland through an ETa receptor subtype (Cartier et al 1997). As previously demonstrated in the lizard Podarcis sicula , ET-1 plays a role in the secretion of catecholamines and steroids from chromaffin and steroidogenic tissue of the adrenal gland, respectively (De Falco et al 2001); furthermore, it also influences thyroid gland activity in this reptile (Virgilio et al 2003) and an ETb receptor is present in P. sicula tissues (De Falco et al 2002). These findings suggest the presence of an endothelin system in lower vertebrates as well as in mammals, even if nothing is known about the presence and localization of ECE enzymes in these animals.…”

Localization and role of leptin in the thyroid gland of the lizardPodarcis sicula (reptilia, lacertidae)

“…Plasma levels of T3 and T4 were determined by the method described by Sciarrillo et al (2000) and Virgilio et al (2003). In brief, they have used sensitive and highly specific radioimmunoassay kits (Byk-Sangtec Diagnostica, Dietzenbach, Germany).…”