Alberto Martini

Opiates and their antagonists modulate luteinizing hormone acting outside the blood brain barrier

The effects of morphine methyl-iodide and naloxone methyl-bromide, two quaternary derivatives of morphine and naloxone, were evaluated on the modulation of luteinizing hormone secretion in intact and gonadectomized rats. Quaternary compounds are effective in modulating LH release, indicating a site outside the blood brain barrier for their action. More precisely, the median eminence and not the pituitary seems to be the site of action of opiates in modulating LH secretion, since the effect of the quaternary derivatives is abolished by surgical ablation of the median eminence.

Brain β-endorphin concentrations in experimental chronic liver disease

Abstract β-Endorphin, Met-enkephalin, substance P and somatostatin concentrations have been evaluated in brain areas of rats with severe liver disease obtained by chronic pretreatment with CCl 4 for 3 or 9 weeks. β-Endorphin, but not Met-enkephalin, somatostatin or substance P concentrations were significantly decreased in the hypothalamus of both the three and nine week-treatment groups. The β-endorphin decrease we observed might be tentatively attributed to a modification of GABA levels, but not serotonin, since the stimulation of the serotoninergic system induced a significant increase, while the potentiation of the GABAergic system induced a clear decrease of β-endorphin concentrations in the hypothalamus of treated rats.

Antiepileptic Agents Affect Hypothalamic β-Endorphin Concentrations

Abstract: β‐Endorphin, Met‐enkephalin, substance P, and somatostatin concentrations were evaluated in the hypothalami of rats treated either acutely or chronically (15 days) with sodium valproate, diphenylhydantoin, phenobarbital, or ethosuximide. All of these drugs, with the exception of ethosuximide, induced significant decreases in β‐endorphin concentrations after acute treatment, while only sodium valproate induced a decrease after chronic treatment. The acute and chronic effects of sodium valproate were also produced by aminooxyacetic acid, an inhibitor of γ‐aminobutyric acid (GABA) transaminase, while another GABA transaminase inhibitor, ethanolamine‐O‐sulphate, and THIP, a GABA receptor agonist, were effective after acute administration. Metenkephalin, substance P, and somatostatin concentrations were never affected by the drugs used. The present results, indicating that antiepileptic agents specifically decrease β‐endorphin concentrations, seem to correlate well with the capacity of these agents to blunt the epileptic activity of the peptides tested. Moreover, our data suggest that GABA may be involved in the anticonvulsant‐induced reduction of β‐endorphin concentrations.

Capsaicin decreases B-endorphin hypothalamic concentrations in the rat

Capsaicin has been administered intraventricularly to adult rats and subcutaneously to neonatal rats. Adult rats were killed three, five, seven and fifteen days after capsaicin administration, while rats treated neonatally were killed when six months old. In the adult rats capsaicin induced a decrease in hypothalamic B-endorphin concentrations three, five and seven days after treatment, while they returned to normal values by day fifteen. A decrease in B-endorphin hypothalamic concentrations was also present in rats treated neonatally, while substance P, somatostatin and met-enkephalin concentrations were never affected by capsaicin treatment.

Brain cholecystokinin-8 immunoreactivity in rats with experimental liver cirrhosis.

Cholecystokinin-8 like immunoreactivity (CCK-8 IR) was measured in different brain regions of rats with experimental liver cirrhosis. A statistically significant reduction of CCK-8 content was observed in the hypothalamus of cirrhotic rats. No significant modification of brain CCK fractionation pattern was observed in treated animals as compared to controls. The decrease of CCK-8 IR parallels the recently reported hypothalamic depletion of beta endorphin in cirrhotic rats confirming that central neuropeptides are affected by chronic liver failure.

Endocrinological responses in cluster headache.

Growth hormone and prolactin levels and their response to various stimuli were studied in patients with cluster headache. All the endocrine responses evaluated were normal.

Effects of β-endorphin fragment 6–31 on morphine- and β-endorphin-induced growth hormone and prolactin release

Abstract A fragment of human β-endorphin (β h -EP-(6–31)) has been proposed as an endogenous inhibitor of β-endorphin. We have evaluated the effects of the fragment on β-endorphin- and morphine-induced prolactin and growth hormone release. It inhibited both morphine- and β-endorphin-induced prolactin release, while it was ineffective on the release of growth hormone.