title: Subcellular distribution of opioid peptides in rat hypothalamus and pituitary.
abstract: Homogenates of rat anterior lobe (AL) and neurointermediate lobe (NIL) pituitary and rat hypothalamus were subjected to subcellular fractionation and density gradient centrifugation. The subcellular distribution of immunoreactive dynorophin A (ir-Dyn A) in NIL was found to be similar to that of ir-arginine vasopressin (ir-AVP). ir-Dyn A migrated as a discrete band on sucrose density gradients, which corresponded in sedimentation rate to that of ir-AVP, suggesting that these two peptides are stored within organelles of similar size and density. Two other products of prodynorphin, ir-alpha-neoendorphin (ir-alpha-nEND) and ir-Dyn A-(1-8) also comigrated with ir-AVP. ir-[Leu5]-enkephalin (ir-LE), which may be a product of prodynorphin or proenkephalin, was also found to migrate in this region of the gradient. When a homogenate of rat hypothalamus was prepared using a method that has been developed for synaptosome isolation, ir-Dyn A was found to comigrate with Na+/K+-activated adenosine triphosphatase (Na/K-ATPase), a synaptosomal marker enzyme. Using a more concentrated homogenate ir-Dyn A was found to migrate to a less dense region where peptide-containing synaptic vesicles have previously been localized. When a synaptosomal preparation was lysed in hypotonic solution a shift was seen in the migration rate of ir-Dyn A to this region of the gradient (containing putative synaptic vesicles). Thus the bulk of hypothalamic dynorphin appears to be present within synaptosome-like structures which, upon lysis, release a less dense, smaller subcellular organelle corresponding in sedimentation characteristics to other types of peptide-containing synaptic vesicles.(ABSTRACT TRUNCATED AT 250 WORDS)
mesh_terms: D000818:Animals; D001127:Arginine Vasopressin / Q000378:metabolism; D002499:Centrifugation, Density Gradient; D004399:Dynorphins / Q000378:metabolism; D004723:Endorphins / Q000378:metabolism*; D004743:Enkephalin, Leucine / Q000378:metabolism; D004744:Enkephalin, Methionine / Q000031:analogs & derivatives / Q000378:metabolism; D007031:Hypothalamus / Q000648:ultrastructure*; D008297:Male; D010446:Peptide Fragments / Q000378:metabolism; D010902:Pituitary Gland / Q000648:ultrastructure*; D011498:Protein Precursors / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D013347:Subcellular Fractions / Q000378:metabolism; D013572:Synaptic Vesicles / Q000378:metabolism; D013574:Synaptosomes / Q000378:metabolism
chemical_list: D004723:Endorphins; D010446:Peptide Fragments; D011498:Protein Precursors; D001127:Arginine Vasopressin; D004744:Enkephalin, Methionine; D004743:Enkephalin, Leucine; C025681:alpha-neoendorphin; C027511:enkephalin-Met, Arg(6)-Phe(7)-; D004399:Dynorphins; C026770:dynorphin (1-8)