Naloxone Induced Enhancement of Systolic Blood Pressure and Reduction of Hypothalamic Catecholamine Levels in Male SHR

Abstract

These results demonstrated that Nal enhanced BP both Int and Cast male and female SHR but, the significant increase appeared only in castrated male and female SHR, suggesting that brain opiates increased by a lack of negative feed-back mechanisms due to Cast (it may be increased GTH), thus, the BP led to decreasing. Reasonably Nal act to inhibited the activity of brain opiate system, then the BP appeared as increasing. In correlation between BP and hypothalamic NE in groups of Int and Cast SHR, when hypothalamic NE was increased, the BP showed lower value, meaningly, while BP increased with Nal, hypothalamic NE decreased. However, though the pressor response by Nal was significantly higher in Cast-group than that of Int-group, the decreasing rate was lower in the former. Thus, sensitivity of hypothalamic NE to antihypertensive action was potensiated by castration. Resulting information with Epi was same as NE as above mentioned. Additionaly, it should be noted that content of Epi was 1/20 of NE.