ИСТИНА

Stress frequently causes dysbiosis, disrupting the balance among the bacterial inhabitants of the gastro-intestinal tract. Catecholamines released into the bloodstream under stress stimulate the growth of opportunistic intestinal pathogens . The goal of this work was to elucidate the effects of catecholamines and related neuroactive compounds on the growth chracteristics of beneficial lactobacilli exemplified by the strain Lactobacillus acidophilus NK-1. An L. acidophilus NK-1 culture was grown for 48 hs anaerobically on the modified MRS medium with cysteine. The tested growth variables included colony-forming unit formation, optical density at 520 nm, and medium acidification. Since these variables behaved in unison, only the CFU data are presented below. Norepinephrine, the main stress-associated neurochemical, drastically (~4-fold) increases the CFU number at concentrations as low as 1 nM; however, CFU formation is inhibited at very high norepinephrine concentrations (> 10 M). Dopamine and epinephrine strimulate CFU formation less efficiently and at relatively high concentrations. Serotonin contained in the chromaffine granules of the intestinal mucosa only insignificantly (by ~25%) stimulates CFU formation. The proinfammatory agent histamine increases the CFU number 2.5-3-fold at a concentration of 1 M. The results obtained provide evidence that neurochemicals produced under stress stimulate the proliferation of a beneficial (probiotic) bacterial strain. These findings point to an ambivalent influence of stress that should increase the growth of both beneficial and detrimental bacteria in the GI tract and, therefore, presumably