Signal transduction mechanisms for autocrine/paracrine regulation of somatolactln-a secretion and synthesis in carp pituitary cells by somatolactin-alpha and -beta

摘要

Pituitary hormones can act locally via autocrine/paracrine mechanisms to modulate pituitary functions, which represents an interesting aspect of pituitary regulation other than the traditional hypothalamic input and feedback signals from the periphery. Somatolactin, a member of the growth hormone (GH)/prolactin (PL) family, is a pleiotropic hormone with diverse functions, but its pituitary actions are still unknown. Recently, two SL isoforms, SL alpha and SL beta, have been cloned in grass carp. Based on the sequences obtained, recombinant proteins of carp SLalpha and SL beta with similar bioactivity in inducing pigment aggregation in carp melano-phores were produced. In carp pituitary cells, SLa secretion and cell content were elevated by static incubation with recombinant carp SLa and SLbeta, respectively.