Prolactin alters the expression of integumental glycoconjugates in the red‐spotted newt, Notophthalmus viridescens

Abstract

Prolactin (PRL)-mediated changes in the texture and secretory activity of the skin in adult red-spotted newts may involve alterations in the distribution and/or expression of structural and secretory epidermal glycoconjugates. To explore this possibility, skin samples were obtained from groups of conditioned animals that had received injections of either ovine prolactin or amphibian saline over a 14-day period. Glycoconjugates within the epidermis and cutaneous glands were examined by means of lectin histochemistry using a panel of eight HRP-labelled lectins. PRL increased levels of sialic acid and n-acetylglucosamine in the stratum corneum. In contrast, glycoconjugates containing fucose, galactose, n-acetylgalactosamine, and galactose-(1,3)-n-acetylgalactosamine were decreased by PRL within both glands and epidermis. These results suggest that the integumental effects associated with prolactin in the red-spotted newt are mediated, at least in part, through the alteration of epidermal and glandular glycoconjugates.

Localization of prolactin receptor in the dorsal and ventral skin of the frog (Rana ridibunda)

“…Storage and maturation of serous product occurs within the syncytical cytoplasm (Delfino 1991). Singhas & Ward (1993) showed that glycoconjugates containing fucose and N-acetylgalactosamine residues within granular glands reduced after treatment with PRL of red spotted newts. PRLR, found in the secretory epithelium of granular glands, indicates that this hormone may regulate the composition of the granular gland product.…”

“…External PRL treatment caused changes in expression of the structural and secretory epidermal glycoconjugates in red spotted-newt (Singhas &Ward 1993). Faszewski & Kaltenbach (1995) suggested that different glycoconjugate patterns in dorsal and ventral skin of the terrestrial horned frog Ceratophrys ornata Bell, 1843 may be associated with the regulation of water balance, and other authors have reported that glycoconjugates in the epidermis of Rana perezi Seoane, 1885 and Pleurodeles waltii Michahelles, 1830 may be involved in epidermal permeability (Bueno et al 1981;Navas et al 1987).…”

“…Therefore, the skin is protected and kept moist by the mucus produced by mucous glands (Li et al 2006). In studies with red-spotted newt, it was shown that PRL alters the secretion of mucous glands (Hoffman & Dent 1978;Singhas & Ward 1993), and in this regard the capability of mucous glands to respond to the external PRL application indicates the presence of PRLR in the gland cells. However, we did not observe PRLR in the mucous glands of R. ridibunda skin, and as thus, we can postulate that these glands are not influenced by PRL.…”

“…In amphibians, prolactin participates in processes regulating growth, metamorphosis, osmoregulation and re-production (Iwata et al 2000;Yamamoto et al 2000;Takada & Hokari 2007). Studies with exogenous PRL treatment in amphibians have shown changes in skin permeability (Brown et al 1991;Takada 2005;Takada & Hokari 2007), and in skin morphology and secretory activity (Dent 1975;Hoffman & Dent 1978;Singhas & Ward 1993).…”

Modern Glycohistochemistry: A Major Contribution to Morphological Investigations

“…Both the integumental and behavioral effects of prolactin in the red-spotted newt may derive from the osmoregulatory action of this hormone (Bern, 1975). Lectin histochemistry has been employed to stress possible relations between prolactin-induced changes in texture and secretory activity, and changes in the distribution and expression of glycans in the skin of the adult red-spotted newt (Singhas and Ward, 1993). These authors report that prolactin increases levels of sialic acid and N-acetylglucosamine in the stratum corneum.…”