Insulin versus glucagon crosstalk: central plus peripheral mechanisms.

Plasma glucose level depends on the peripheral intra-islet crosstalk between A cells (glucagon) + B-cells (insulin) and D-cells (somatostatin). Gastrointestinal hormones (secretin, CCK-PZ, gastrin, and serotonin) modulate the glucose- and amino acids-induced secretions of insulin and glucagon, respectively. Serotonin (5-HT) arose from the enterochromaffin cells during postprandial periods excites basal but inhibits excited B-cells.

Anorexia nervosa versus hyperinsulinism: therapeutic effects of neuropharmacological manipulation.

Background: We have demonstrated that anorexia nervosa is underpinned by overwhelming adrenal sympathetic activity which abolishes the neural sympathetic branch of the peripheral autonomic nervous system. This physiological disorder is responsible for gastrointestinal hypomotility, hyperglycemia, raised systolic blood pressure, raised heart rate, and other neuroendocrine disorders. Therefore, we prescribed neuropharmacological therapy to reverse this central and autonomic nervous system disorder, in order to normalize the clinical and neuroendocrine profile.

Effects of amantadine on circulating neurotransmitters in healthy subjects.

Considering that glutamatergic axons innervate the C1(Ad) medullary nuclei, which are responsible for the excitation of the peripheral adrenal glands, we decided to investigate catecholamines (noradrenaline, adrenaline and dopamine) plus indolamines (plasma serotonin and platelet serotonin) at the blood level, before and after a small oral dose of amantadine, a selective NMDA antagonist. We found that the drug provoked a selective enhancement of noradrenaline plus a minimization of adrenaline, dopamine, plasma serotonin and platelet serotonin circulating levels. Significant enhancement of diastolic blood pressure plus reduction of systolic blood pressure and heart rate paralleled the circulating parameter changes.

Effects of an oral dose of l-glutamic acid on circulating neurotransmitters: Possible roles of the C1(Ad) and the A5(NA) pontomedullary nuclei.

Objective: Investigation of the effects of an oral administration of a small dose of l-glutamic acid on the two peripheral sympathetic branches (neural and adrenal) of the autonomic nervous system.

Research Design And Methods: Circulating neurotransmitters and cardiovascular parameters were assessed in 28 healthy volunteers before and after the administration of 500 mg of l-glutamic acid or placebo.

Results: The drug triggered a significant and sustained enhancement of the noradrenaline and dopamine circulating levels which were paralleled and positively correlated with the diastolic blood pressure increases.

Anorexia nervosa depends on adrenal sympathetic hyperactivity: opposite neuroautonomic profile of hyperinsulinism syndrome.

Objective: The aim of our study was to determine the central and peripheral autonomic nervous system profiles underlying anorexia nervosa (AN) syndrome, given that affected patients present with the opposite clinical profile to that seen in the hyperinsulinism syndrome.

Design: We measured blood pressure and heart rate, as well as circulating neurotransmitters (noradrenaline, adrenaline, dopamine, plasma serotonin, and platelet serotonin), using high-performance liquid chromatography with electrochemical detection, during supine resting, one minute of orthostasis, and after five minutes of exercise. In total, 22 AN patients (12 binge-eating/purging type and 10 restricting type) and age-, gender-, and race-matched controls (70 ± 10.