Dynorphin is found mainly in the particulate fraction of rat pituitary gland and hypothalamus homogenates. Dynorphin-like immunoreactivity (DYN-LI) from neurointermediate lobe (NIL) homogenates migrates at the same rate as vasopressin-like immunoreactivity (AVP-LI), in sucrose density gradients, whereas DYN-LI from the hypothalamus appears to migrate principally in a less dense region of the gradient. This suggests that dynorphin and vasopressin from pituitary are present in organelles of similar size and density, while the bulk of the dynorphin in the hypothalamus appears to be stored in a different subcellular organelle. Anterior lobe (AL) dynorphin appears to migrate in two separate bands on density gradients: the less dense band (slower) migrates at a similar rate to that of dynorphin and vasopressin from NIL. When alpha-neo-endorphin was measured in sucrose gradients of NIL and hypothalamus, it was found to co-migrate with DYN-LI.

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PubMedDate not supplied

Dynorphins and Leu-enkephalin in brain nuclei and pituitary of WKY and SHR rats.

The distribution of dynorphin 1-13 (Dyn-1-13, Dyn-(1-8) and Leu5-enkephalin (LE) immunoreactivities (ir) were determined in discrete brain nuclei of normotensive (WKY) and hypertensive (SHR) rats. The concentration of ir-Dyn-(1-13) and ir-Dyn-(1-8) varied markedly among the various nuclei studies with a predominance of ir-Dyn-(1-13) over ir-Dyn-(1-8) in all the nuclei of both WKY and SHR rats. Ir-LE also showed large variations in different sites and no consistent relationships were found between the distribution of ir-Dyn-(1-8), Dyn-(1-13) and LE. SHR rats had lower levels of ir-Dyn-(1-13), Dyn-(1-8) and LE in the suprachiasmatic nucleus compared with WKY rats. In addition, SHR rats had lower levels of ir-Dyn-(1-8)- in the paraventricular and central amygdala, and higher ir-Dyn-(1-13) levels in the substantia nigra. The level of ir-Dyn-(1-13) in the neurointermediate lobe (NIL) of SHR rats was decreased substantially compared with that of WKY rats. The localization of these opioid peptides suggests that dynorphin-like peptides may serve a variety of hypothalamic and extrahypothalamic functions which might differ between SHR and WKY rats.

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PubMedDate not supplied

Vasoactive intestinal polypeptide carboxy-terminal fragment, VIP(22-28), and other fragments of VIP, in the central nervous system of the rat.

The possible existence in rat brain tissues of shorter peptides related to VIP has been examined. VIP and PHI both contain paired basic amino acid residues at which posttranslational cleavage of these peptides might occur. Antiserum to VIP(22-28) was raised in rabbits. The antiserum was carboxy-terminus directed, showing cross-reactivity with all tested peptides containing the VIP carboxy-terminus sequences. Chromatographic analysis of rat brain extracts demonstrated that recovered VIP(22-28) immunoreactivity [VIP(22-28)-ir] was heterogeneous, consisting of a major fraction [60-70% of total VIP(22-28)-ir] which eluted as authentic VIP(1-28) on gel filtration and on reversed phase high performance liquid chromatography (HPLC) columns. A second fraction (30-35% of total VIP(22-28)-ir] eluted from gel filtration columns in the position of VIP(22-28). HPLC analysis of this fraction from extracts of rat cortex, hippocampus, and midbrain indicated that it was heterogeneous. One component corresponded to authentic VIP(22-28). The other two components have not been identified; one appears to be a VIP fragment intermediate in size between VIP(1-28) and VIP(22-28).

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PubMedDate not supplied

Peptide biosynthesis.

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