Relationship of Urinary Serotonin Excretion to Cigarette Smoking and Respiratory Symptoms

Susceptibility of the aging lung to environmental injury

With an ever-increasing number of elderly individuals in the world, a better understanding of the issues associated with aging and the environment is needed. The respiratory system is one of the primary interfaces between the body and the external environment. An expanding number of studies suggest that the aging pulmonary system (>65 years) is at increased risk for adverse health effects from environmental insult, such as by air pollutants, infection, and climate change. However, the mechanism(s) for increased susceptibility in this subpopulation are not well understood. In this review, we provide a limited but comprehensive overview of how the lung ages, examples of environmental exposures associated with injury to the aging lung, and potential mechanisms underlying the increased vulnerability of the aging lung to injury from environmental factors.

Antiplatelet activity during coadministration of the selective serotonin reuptake inhibitor paroxetine and aspirin in male smokers: a randomized, placebo-controlled, double-blind trial

Depression is associated with an increased incidence of vascular events and develops after stroke and myocardial infarction. Beside potential clinical outcome benefits of selective serotonin reuptake inhibitors for vascular diseases, bleeding events were reported. We investigated whether paroxetine and aspirin synergistically inhibit platelet function. Paroxetine (20 mg/d) was administered over 18 days to 20 men in a randomized, placebo-controlled, crossover design. Aspirin (100 mg/d) was coadministered within the last 4 study days. Platelet function was assessed by the platelet function analyzer and by flow cytometry. Paroxetine prolonged epinephrine-dependent predictive index within 14 days (P<.02). Aspirin enhanced the predictive index (P<.004 vs baseline and P>.05 between periods). A trend toward decreased thrombin receptor-activating peptide-induced CD62P expression after paroxetine was further enhanced by aspirin treatment (P>.05 between periods). The combination of paroxetine and aspirin did not further inhibit platelet plug formation under high shear stress in male smokers.

Increased serotonin receptor density and platelet GPIIb/IIIa activation among smokers

This study sought to determine whether depressive symptoms and/or platelet serotonin receptor (5HT2A) density are associated with increased platelet activation (PA) found among smokers. Flow cytometric detection of PA was used to study 36 smokers and 16 nonsmokers, aged 18 to 48 years. Subjects were tested at baseline and after either smoking 2 cigarettes (smokers) or a similar resting interval (nonsmokers). Assessment of PA included both platelet secretion and fibrinogen receptor (GPIIb/IIIa) binding. Platelet 5HT2A receptor binding and saturation were tested using [3H]LSD, and depressive symptoms were measured using the Beck Depression Inventory. Platelet 5HT2A receptor density was increased among smokers versus nonsmokers (82.7+/-67.7 versus 40.0+/-20.2 fmol/mg protein; P<0.005), and there was a dose-dependent relationship between receptor density and packs/d among smokers. Baseline wound-induced GPIIb/IIIa binding at 1 minute and GPIIb/IIIa binding in response to collagen stimulation in vitro was increased among smokers (P<0.05); there were no changes in PA among smokers after smoking, and platelet secretion was not elevated among smokers. Depressive symptoms were associated with 5HT2A receptor density among nonsmokers (P<0.005), but no such relationship was evident among smokers; PA was unrelated to 5HT2A receptor density in either group. The findings indicate that smoking is associated with increased platelet serotonin receptor density and with increased GPIIb/IIIa receptor binding, although these 2 factors are not related to each other or to depressive symptoms among smokers. Serotonergic dysfunction may be an important factor in the development of cardiovascular disease among smokers.