Development of cerebral methionine-enkephalinergic neurons in rats: Some difference in Wistar-Kyoto rats and spontaneously hypertensive rats

Nakamura, Keiji; Hayashi, Tetsuo

doi:10.1016/0006-8993(83)91361-6

Cited by 9 publications

(1 citation statement)

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“…but with increased levels in the pons-medulla and cortex. Neonatal SHR have been found to have much lower levels of ME than WKY of equivalent ages in a num ber of cerebral and spinal nerve tracts and in norepinephrine-containing cell groups of the medulla, a finding the authors claimed to be associated with central sympathetic hyper reactivity in spinal sympathetic centers of SHR [21,22], Our findings of a normalization of the increased BE and ME levels only in the inter mediate lobe, after antihypertensive drug therapy, were surprising to us and suggest that, at least in this region, the opioid peptide changes may be secondary to the generalized blood pressure increase. This interpretation would be opposed to our data with the DOCA-salt-treated rats, wherein no changes in pituitary opioids were noted as a result of the hypertension in this model.…”

Section: Discussionmentioning

confidence: 98%

Age-Related Changes in Opioid Peptide Concentrations in Brain and Pituitary of Spontaneously Hypertensive Rats

Wong

Hong

et al. 1992

Pharmacology

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The relationship of age-dependent changes in concentrations of various opioid peptides in the brain and pituitary to the development of hypertension was studied in the spontaneously hypertensive rat (SHR). Normotensive Wistar-Kyoto (WKY) and Sprague-Dawley rats served as controls. Opioids determined were dynorphin A (1-8) [DN-A(1–8)], β-endorphin (BE) and Met-enkephalin (ME). Three approaches were used: (1) temporal correlations of opioid concentrations with the onset of hypertension in 4-, 8-, 12- and 16-week-old rats; (2) study of opioid changes when hypertension development was prevented with antihypertensive drugs and (3) determination of possible opioid peptide changes in another rat model of hypertension, the deoxycorticosterone acetate (DOCA) + salt model. Opioid peptide concentration differences (SHR/ WKY) found were as follows. There were much lower DN-A(1–8) levels in the SHR hippocampus and hypothalamus at all ages studied. At 12 and 16 weeks, coincidently with the onset of hypertension, lower levels of BE were found in the anterior lobe of the pituitary, but there were higher BE and ME levels found in the neurointermediate lobe (NIL). Prevention of hypertension in SHR by 8 weeks of oral therapy with guanethidine and hydralazine reversed the BE and ME changes in the NIL but not in the anterior lobe. There were no brain or pituitary changes in opioid peptide concentrations associated with DOCA-salt hypertension. The results are interpreted as supporting a role for altered concentrations of brain and pituitary opioids in the genesis of SHR hypertension.

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Section: Discussionmentioning

confidence: 98%