Methylhistamine and Histamine in the Urine of Women During the Elaboration of Œstrogen

Urinary excretion of N-methylhistamine as a marker of disease activity in inflammatory bowel disease

OBJECTIVE

Mast cells are thought to participate in the pathogenesis of inflammatory bowel disease (IBD). In this study, urinary excretion of N-methylhistamine (UMH), a stable metabolite of the mast cell mediator histamine, was evaluated as an indicator of disease activity in patients with IBD.

METHODS

Urinary excretion of UMH (microg/mmol creatinine x m2 body surface area) was measured by radioimmunoassay in 55 controls, 56 patients with Crohn's disease, and in 36 patients with ulcerative colitis. Excretion rates were correlated with clinical, serological, and endoscopic disease activity, disease extent, and location.

RESULTS

Urinary excretion of UMH was found to be significantly elevated in IBD. Patients with active Crohn's disease (7.1 +/- 4.2, p = 0.002 vs controls) and active ulcerative colitis (8.1 +/- 4.8, p = 0.02 vs controls) had higher rates of UMH excretion than patients in remission (6.3 +/- 3.8 and 5.2 +/- 2.3, respectively) or controls (4.6 +/- 1.9). In Crohn's disease and ulcerative colitis, a significant correlation of UMH excretion with clinical disease activity was obtained (Crohn's Disease Activity Index r2 = 0.58, Clinical Activity Index r2 = 0.57, p < 0.0001). Serologically, orosomucoid showed the best positive correlation with disease activity (Crohn's Disease Activity Index r2 0.80, Clinical Activity Index r2 = 0.86, p < 0.0001), but UMH excretion was found to reflect disease activity more accurately than C-reactive protein (Crohn's Disease Activity Index r2 = 0.46, Clinical Activity Index r2 = 0.42, p < 0.0001). No association between UMH excretion and disease type or localization could be found in Crohn's disease. However, UMH excretion correlated strongly with endoscopic severity of inflammation in Crohn's disease (Crohn's Disease Endoscopic Index of Severity r2 = 0.70, p < 0.0001) or disease extent in ulcerative colitis.

CONCLUSIONS

Urinary excretion of the histamine metabolite UMH is enhanced in IBD. It appears to represent an integrative parameter to monitor clinical and endoscopic disease activity in IBD, which appears to be influenced most likely by mediators released from histamine-containing cells, such as intestinal mast cell subtypes.

Effect of in vivo antiestrogen pretreatment on rabbit atrial chronotropic response to histamine

The chronotropic response (delta rate) to histamine (1.4 to 18 X 10(-6) M) of isolated atria from antiestrogen (tamoxifen)-pretreated immature female rabbit was investigated. Tamoxifen treatment (1.0 and 10.0 mg/kg/day for 14 days) had no significant effect on the delta rate. The Rmax and D1/2max were not significantly different in the two tamoxifen-treated groups compared to the oil-treated (1.0 ml/kg/day for 14 days) control group. Cimetidine (2.8 X 10(-7) M) inhibited the delta rate to histamine in all groups: control, 27%; tamoxifen (1.0 mg/kg), 38%; and tamoxifen (10.0 mg/kg), 28%. Only the low dose of tamoxifen was found to be estrogenic (uterotropic). We conclude that tamoxifen pretreatment, both at estrogen-agonist and estrogen-antagonist doses, is without effect on atrial chronotropic response to histamine.

Modulation by estradiol of rabbit atrial chronotropic response to histamine

The chronotropic response (delta rate) to histamine of atria from estradiol 17-beta (E2; 0.1 mg/kg)-treated (14 days) rabbit was significantly greater compared to those from control rabbits. However, the maximum response of atria from rabbits treated with a higher dose of E2 (1.0 mg/kg) was not significantly different from control. Cimetidine (2.8 X 10(-7) M) inhibited the theoretical maximum income in rate to histamine in all 3 groups, control 25%, E2 (0.1 mg) 42% and E2 (1.0 mg) 35%.

Measurement of tele-methylhistamine and histamine in human cerebrospinal fluid, urine, and plasma

A gas chromatographic-mass spectrometric method described by us to measure tele-methylhistamine (t-MH) in brain was used to measure t-MH in human cerebrospinal fluid (CSF), urine and plasma. The presence of t-MH in these body fluids was rigorously established. No pros-methyl-histamine could be detected, and it was used as internal standard to quantify t-MH in the fluids. The mean levels of t-MH were: urine, 943 pmol/mg creatinine; plasma, 12.3 pmol/ml; and CSF, 2.2 pmol/ml. Parallel measurements of histamine by a radioenzymatic method showed, respectively, 182 pmol/mg creatinine; 19.5 pmol/ml; and 388 pmol/ml. The levels of HA in CSF, much higher than those of its metabolite, t-MH, are high enough to stimulate HA receptors in the central nervous system.

Histamine and some of its metabolites in human body fluids

The concentrations of histamine, t-methylhistamine and t-methylimidazoleacetic acid were measured in human cerebrospinal fluid, plasma and urine, Especially noteworthy are the levels of histamine in cerebrospinal fluid which are far higher than those of t-methylhistamine and of t-methylimidazoleacetic acid, and high enough to stimulate histamine receptors in the central nervous system. It is suggested that mast cells, which surround the subarachnoid space, may contribute histamine to the cerebrospinal fluid and may offer a target for drugs and for immunologic actions. The t-methylhistamine and t-methylimidazoleacetic acid levels in cerebrospinal fluid may reflect central histaminergic activity, although a source of these metabolites in addition to histamine needs to be considered.