The effect of a highly specific serotonin agonist on osmoregulated vasopressin secretion in healthy man

OBJECTIVE: To explore a possible interaction of the serotonin neurotransmitter system and posterior pituitary function, we have looked at the effect of fluoxetine treatment on osmoregulated vasopressin secretion in normal men in two placebo controlled studies. DESIGN: In each study subjects took in random order for 7 days one capsule daily of placebo or 40 mg fluoxetine. On the 8th day subjects underwent assessment. Study 1 A hypo-osmotic stimulus of an oral water load of 20 ml/kg. Study 2 A hyperosmotic stimulus of intravenous infusion of 5% (855 mmol/l) saline at 0.06 ml/kg/min for 120 minutes. PATIENTS: Normal, healthy male volunteers. Study 1, 9; Study 2, 10. MEASUREMENTS: In both studies regular measures of plasma osmolality, sodium and vasopressin were made. In Study 1 urine osmolality was measured together with urine volume at set time points and an accumulative measure of percentage of water load excreted. Free water clearance was calculated. In Study 2 the relationship of plasma vasopressin to change in plasma osmolality was calculated for each subject by linear regression analysis. RESULTS: Serotonin agonism had no effect on baseline measurements in either study. Study 1 After 4 hours subjects excreted 95 and 99% of the water load after placebo and fluoxetine respectively (P = 0.407). There was no effect of fluoxetine compared to placebo on the pattern or extent of change of plasma osmolality (nadir 285.9 +/- 1.4 mosm/kg placebo, 283.1 +/- 1.1 mosm/kg fluoxetine, P = 0.145) or free water clearance or maximum urine dilution after oral water loading. Plasma vasopressin suppressed to a minimum concentration after both treatments in response to hypo-osmolality 0.5 +/- 0.1 pmol/l (placebo), 0.3 +/- 0.01 pmol/l (fluoxetine), P = 0.195. Study 2 Fluoxetine had no significant effect on the sensitivity of vasopressin release to change in plasma osmolality (0.33 +/- 0.06 pmol/l per mosm/kg placebo, 0.36 +/- 0.06 pmol/l per mosm/kg fluoxetine, P = 0.347). Nor was there a significant effect on the theoretical osmotic threshold for release of vasopressin (287.0 +/- 1.21 mosm/kg placebo, 286.9 +/- 1.09 mosm/kg fluoxetine, P = 0.700). CONCLUSION: We have found no evidence of a physiologically relevant effect of serotonin agonism on osmoregulated vasopressin release, or on the ability of normal man to excrete a water load. The possible reasons for this contrast to animal work are discussed.     

Neuroendocrine and neurochemical measurements in depression

The authors performed dexamethasone suppression tests (DST), TRH infusions, 72-hour urine collections, and lumbar punctures on a group of male depressed patients. Approximately 60% of the patients were DST positive and 33% had a blunted TSH response. Two biologic variables, the 8 a.m. postdexamethasone cortisol and the postprobenecid CSF 5-hydroxyindoleacetic acid (5-HIAA), accounted for over half of the variance in the behavioral measure, the Hamilton score. Plasma cortisol elevation was associated with high 3-methoxy-4-hydroxyphenyl glycol (MHPG) excretion; TSH blunting was associated with low urinary MHPG excretion. Comprehensive biologic measures showed certain significant interrelationships and correlations with the severity of depression.     

1,2,4-Triazolo[4,3-a]pyrazine derivatives with human renin inhibitory activity. 1. Synthesis and biological properties of alkyl alcohol and statine derivatives

A series of 1,2,4-triazolo[4,3-a]pyrazine derivatives with human renin inhibitory activity, which incorporate (1S,2S)-2-amino-1,3-dicyclohexyl-1-hydroxypropane, statine (Sta), and (3S,4S)-4-amino-5-cyclohexyl-3-hydroxy-pentanoic acid (ACHPA) transition-state mimetics, have been prepared. Structure-activity relationships for renin inhibitory activity in the series are consistent with the 2-[8-isobutyl-6-phenyl-1,2,4-triazolo[4,3-a]pyrazin-3-yl]-3-(3 pyridyl)propionic acid moiety 10b acting as a non-peptidic replacement for the P4-P2 (Pro-Phe-His) residues of the natural substrate angiotensinogen. Compounds 12m, 12o and 12q were potent inhibitors of partially purified human renin (IC50 values 1.7, 6.8, and 3.7 nM, respectively), and also effectively lowered blood pressure in anesthetized, sodium depleted marmosets following intravenous administration. On oral administration however, no blood pressure lowering activity could be detected, and absorption studies in bile duct cannulated rats indicate that this may be due primarily to poor oral absorption, rather than rapid biliary excretion. The reason for the observed poor oral activity is not clear, but it seems unlikely that poor aqueous solubility or metabolic instability to gut enzymes are rate-determining, and other factors such as high molecular weight may also be very important.     

A randomized controlled trial of electromagnetic therapy in the primary care management of venous leg ulceration

OBJECTIVE: The aim was to establish the potential efficacy, tolerabilityand side-effect profile of electromagnetic therapy as an adjunctto conventional dressings in the treatment of venous leg ulcers. METHOD: A prospective, randomized, double blind controlled clinicaltrial was carried out in a dedicated leg ulcer clinic basedin one urban general practice. Nineteen patients with leg ulcersof confirmed venous aetiology were assessed. The main outcomemeasures were rate and scale of venous leg ulcer healing, changesin patient-reported pain levels, quality of life, degree ofmobility, side effect profile and acceptability to patientsand staff. RESULTS: Sixty-eight per cent of patients attending this dedicated clinicachieved improvements in the size of their ulcer (4, 21%, healedfully) and in reduced pain levels (P < 0.05) during the trial,despite the chronicity of ulcer histories. Patients treatedwith electromagnetic therapy at 800 Hz were found at day 50to have significantly greater healing (P < 0.05) and paincontrol (P < 0.05) than placebo therapy or treatment with600 Hz. All patients reported improved mobility at the end ofthe study. The electromagnetic therapy was well tolerated bypatients, with no differences between groups in reporting adverseevents, and proved acceptable to staff. CONCLUSION: Despite the small numbers in this pilot study, electromagnetictherapy provided significant gains in the healing of venousleg ulcers and reduction in pain. Keywords. Electromagnetic therapy, RCT, leg ulcers, primary care.