Evidence for enkephalin- and endorphin-immunoreactive cells in the anterior pituitary of the axolotl Ambystoma mexicanum

Detection of prodynorphin end products in lizard, turtle, and alligator brain extracts

Heterologous radioimmunoassays (RIAs) for the mammalian prodynorphin end products, alpha-neo-endorphin, dynorphin A(1-17), dynorphin A(1-8), and dynorphin B(1-13) were used to screen brain extracts obtained from representatives of the major surviving orders of reptiles: Chelonia (Pseudemys scripta), Squamata (Anolis carolinensis), and Crocodylia (Alligator mississippiensis). Methanol/acid extracts of whole brains obtained from each species were separately fractionated by gel filtration chromatography and reversed-phase HPLC. In all three species, an immunoreactive form of alpha-neo-endorphin was detected with the same retention time as synthetic mammalian alpha-neo-endorphin following reversed-phase HPLC analysis. In all three species, reversed-phase HPLC analysis revealed a novel form of dynorphin B(1-13)-related immunoreactivity. With the available immunological probes, dynorphin A products were only detected in the Anolis brain extracts. Both dynorphin A(1-17) and dynorphin A(1-8) were detected in this species.