Changes in Kynurenine Pathway Metabolites After Acute Psychosocial Stress in Healthy Males: A Single-Arm Pilot Study, 2021, La Torre et al

[Andy]

Abstract

Chronic stress is associated with an increased conversion of tryptophan (TRP) into kynurenine (KYN). However, only a few studies investigated KYN pathway metabolite concentrations following acute stress in healthy subjects. We hypothesized that TRP/KYN metabolism changes following acute stress, and that KYN pathway metabolites are associated with cortisol and subjective stress responses.

In a single-arm pilot study, we explored whether KYN pathway metabolites concentrations were altered after acute stress induced by the Maastricht Acute Stress Test in healthy males (n = 56, mean age: 27 (SD =4.5) years, BMI: 23 (SD =1.8) kg/m2). In particular, we examined whether concentrations of TRP decreased, and KYN, kynurenic acid (KYNA), and the ratio of KYN to TRP (KYN:TRP) increased after acute stress. Furthermore, we assessed whether cortisol and subjective stress responses correlated with KYN pathway metabolite measures after stress induction, based on both the area under the curve with respect to the ground (AUCg) as well as the incremental area under the curve (AUCi). Concentrations of TRP, KYN, KYNA, and KYN:TRP were significantly lower after stress induction compared to pre-stress induction (all p < 0.01). AUCi and AUCg reflecting cortisol and subjective stress responses did not correlate with AUCi and AUCg reflecting KYN pathway metabolite responses.

These preliminary results indicate that KYN pathway metabolites are lower after acute psychosocial stress induction. Moreover, although chronic stress and subsequent prolonged elevated cortisol concentrations and subjective stress stimulate the conversion of TRP into KYN, acute stress is not associated with such conversion up to 35 minutes after stress induction.

Paywall, https://www.tandfonline.com/doi/full/10.1080/10253890.2021.1959546

 

[rvallee]

Impressive level of confusion and, well, more confusion here. It mentions "psychosocial stress" when the MAST is actually this:

Participants were informed that there would be alternating trials of immersing their hand into ice-cold water..., and engaging in a mental arithmetic task (counting aloud backward from 2043 in steps of 17). They were told that the duration of these trials would be randomly chosen by the computer to last between 45 and 90 s and used their non-dominant hand (56 participants were right-handed). In between the hand immersion trials, participants resumed the counting task while they rested their arm on a towel beside the water bath. If they made a mistake with accuracy or did not give a response within 5 s, negative feedback was given by the experimenter and the participant had to start again at 2043. Participants were also informed they would be video-recorded so as to later analyze their facial expressions.

I have no idea what interpretation of acute psychosocial stress makes any sense here, this is clearly a basic physiological/cognitive test and barely at that, sounds more like just basic exertion, no different than playing a game or most sports. Most video games have the same type of "negative" feedback, if that's what they want to argue is "stressful" than basically everything in life is.

Or what do still hold the weird beliefs about doctors being authority figures that people want to impress and so would be stressed out at being told they got wrong answers on a BS test? Pfffft. Even the field of economics takes "all other things being equal" more seriously than this and it it notorious for being creative about it.