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On the origin of Leu-enkephalin and Met-enkephalin in the rat neurohypophysis.
- Source :
-
Endocrinology [Endocrinology] 1985 Oct; Vol. 117 (4), pp. 1687-92. - Publication Year :
- 1985
-
Abstract
- The posterior lobe of the pituitary contains large amounts of Leu- and Met-enkephalin (LE and ME, respectively). A marked depletion of ME (81.9%) and LE (94.5%) in the posterior pituitary occurred after transection of the pituitary stalk. This indicates that most, if not all, of the enkephalins are in processes of central neurons. In the present study, I attempted to determine the source(s) of the LE- and ME-containing fibers in the posterior pituitary by examining the effects of hypothalamic lesions or fiber transections on the LE and ME levels. Lesions of the hypothalamic paraventricular nuclei caused ME and LE levels in the posterior pituitary to decrease significantly (55.6% and 27.6%, respectively). Deafferentation of the medial basal hypothalamus (creating islands of tissue containing the ventromedial and arcuate nuclei) resulted in a marked reduction in LE (94.1%) and ME (54.7%). Treating neonatal rats with monosodium glutamate resulted in a selective destruction of arcuate nucleus neurons, but did not affect LE and ME concentrations in the posterior pituitary. Thus, about half of the ME in the posterior pituitary seems to be provided by neurons in the vicinity of the paraventricular and ventromedial nuclei, whereas only about one quarter of the LE in the posterior pituitary is in processes of the paraventricular nucleus neurons. The remainder of the LE is contributed to the posterior pituitary by neurons outside the medial basal hypothalamus, probably by the supraoptic nucleus neurons. These findings are consistent with the hypothesis that LE and ME may be localized in separate populations of nerve endings in the neurohypophysis and may have different roles.
- Subjects :
- Animals
Arginine Vasopressin analysis
Dynorphins analogs & derivatives
Dynorphins analysis
Endorphins analysis
Hypothalamus, Middle metabolism
Male
Paraventricular Hypothalamic Nucleus analysis
Peptide Fragments analysis
Protein Precursors analysis
Rats
Rats, Inbred Strains
Rats, Inbred WKY
Sodium Glutamate pharmacology
Enkephalin, Leucine biosynthesis
Enkephalin, Methionine biosynthesis
Pituitary Gland, Posterior metabolism
beta-Endorphin analogs & derivatives
Subjects
Details
- Language :
- English
- ISSN :
- 0013-7227
- Volume :
- 117
- Issue :
- 4
- Database :
- MEDLINE
- Journal :
- Endocrinology
- Publication Type :
- Academic Journal
- Accession number :
- 2863131
- Full Text :
- https://doi.org/10.1210/endo-117-4-1687