Different pattern of association of beta-endorphin and cortisol responses to dextroamphetamine in postmenopausal women and young men

B-endorphin response to a low dosage of human corticotropin releasing hormone during metyrapone administration in depression

This study defines the pituitary B-endorphin (BE) secretory response to a low dosage (0.3 ug/kg) of human corticotropin releasing hormone (CRH) in depressed patients and normal controls pretreated with metyrapone. We find no difference in the B-endorphin response to CRH in depressed subjects without evidence of HPA overactivity, compared with controls. This finding is contrasted with other data demonstrating a blunted B-endorphin response to CRH in depressives. The influence of metyrapone pretreatment on the pituitary B-endorphin response to CRH through a mechanism that minimizes the impact of cortisol negative feedback is discussed. Future studies which include low dose CRH infusion both in the presence and in the absence of metyrapone pretreatment will help investigate alterations in the regulation of pituitary B-endorphin secretion in depression including the possibility of increased pituitary sensitivity to the negative fast feedback of cortisol.

Effects of acute and chronic methylphenidate administration on beta-endorphin, growth hormone, prolactin and cortisol in children with attention deficit disorder and hyperactivity

The effect of 5 mg/p.o. methylphenidate (MPH) challenge on beta-endorphin (beta-EP), growth hormone (GH), prolactin (Prl) and cortisol was investigated in 16 children suffering from attention deficit disorder with hyperactivity (ADDH) before and after 4 weeks MPH treatment. The study population consisted of 13 males and 3 females aged 6-11 years. All patients were drug free for at least 3 months prior to investigation. The severity of ADDH symptomatology and response to MPH chronic treatment was assessed using parent/teacher abbreviated Conners rating scale. Blood samples for beta-EP, cortisol, Prl and GH were drawn before initiation of treatment (basal pre-treatment level), 2 hours after MPH challenge, 4 weeks after MPH treatment (basal post-treatment level) and 2 hours after re-challenge with MPH. Chronic MPH treatment resulted in a decrease in basal Prl levels (5.5 +/- 2.8 vs 3.7 +/- 1.9 ng/ml; p less than 0.05). Pre-treatment challenge stimulates significantly both beta-EP (15.0 +/- 7.5 vs 12.5 +/- 5.3 pmol/l; p less than 0.05) and cortisol secretion (20.6 +/- 6.6 vs 12.6 +/- 5.8 micrograms/dl; p less than 0.05), and suppressed Prl secretion (4.0 +/- 1.5 vs 5.5 +/- 2.8 ng/ml; p less than 0.05). Re-challenge with MPH enhanced beta-EP levels (14.9 +/- 8.6 vs 10.6 +/- 5.0 pmol/l; p less than 0.05) but failed to affect cortisol, Prl and GH secretion. The acute and chronic neuroendocrine effects of MPH administration might be related to its dopaminergic and adrenergic agonistic activity. It might be that the stimulatory effect of single and repeated acute MPH administration on beta-EP release contributes to the beneficial effect of MPH treatment in ADDH children.