Increased fecal pellet output that occurs during cold-restraint stress (CRS) was evaluated systematically. Free-feeding rats, which exhibit a reduced occurrence of gastric ulcers under these conditions, were studied. CRS significantly increased fecal pellet production and fluid content. However, the fecal output produced during CRS was not associated with increased gut secretory activity or somatic motor activity associated with cold restraint and did not occur in anesthetized animals. Cold and restraint stress were additive in producing increased fecal output. Significant dose-related decreases in fecal output were produced by drugs that decrease gut transit (i.e., B-HT 920, clonidine, Lomotil, loperamide, and lidamidine). Anticholinergic-antisecretory drugs, antidepressants, and tranquilizers had little effect on fecal output or fluid content. Changes in gastrointestinal transit did not contribute to the increased fecal output during CRS. Transit in the lower small intestine was not altered, but the cecum tended to empty more contents into the large intestine during CRS. Colonic transit was dramatically affected by CRS, which eliminated retrograde transit and produced the evacuation of the majority of colonic contents. The increased colonic transit produced by CRS was decreased in a dose-related fashion by hexamethonium, nifedipine, loperamide, and B-HT 920. In several time-response and drug-inhibition studies during CRS, both fecal pellet output and colonic transit were affected similarly. These data indicate that CRS appears to change central nervous system output to the colon and that it alters colonic smooth muscle motility in a manner that facilitates colonic transit and evacuation. Small intestinal transit is not involved in this phenomenon and is regulated differently during CRS.

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BACKGROUND: Millions of women worldwide use exogenous hormones as oral contraceptives or hormone replacement therapy. Still, time-dependent and long-term consequences of exogenous hormones on stroke risk remains unclear. METHODS: We examined the association between self-reported oral contraceptive and hormone replacement therapy use and stroke risk in 257 194 women from the UK Biobank, born between 1939 and 1970. Outcomes included any type of stroke, ischemic stroke, intracerebral hemorrhage, and subarachnoid hemorrhage. Exposures were analyzed as time-varying variables in Cox regression models. RESULTS: During first year of oral contraceptive use, an increased event rate of any stroke was observed (hazard ratio [HR], 2.49 [95% CI, 1.44–4.30]), while the hazards were found to be comparable during remaining years of use (HR, 1.00 [95% CI, 0.86–1.14]), compared with nonusers. Similarly, first year of hormone replacement therapy use was associated with higher hazard rates of any stroke (HR, 2.12 [95% CI, 1.66–2.70]), as well as cause-specific stroke, including ischemic stroke (HR, 1.93 [95% CI, 1.05–3.57]) and subarachnoid hemorrhage (HR, 2.17 [95% CI, 1.25–3.78]), which remained increased for any stroke during remaining years of use (HR, 1.18 [95% CI, 1.05–1.31]), and after discontinuation (HR, 1.16 [95% CI, 1.02–1.32]). CONCLUSIONS: Oral contraceptive use and hormone replacement therapy were associated with an increased risk of stroke, especially during the first year of use, possibly due to immediate changes in hemostatic balance. This study provides new insights on the effects of hormone exposure on stroke risk and provide evidence of not only an overall risk but also a pronounced effects seen in the beginning of treatment.

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