1.
ABCC1 modulates negative feedback control of the hypothalamic-pituitary-adrenal axis in vivo in humans.
Kyle, CJ, Nixon, M, Homer, NZM, Morgan, RA, Andrew, R, Stimson, RH, Walker, BR
Metabolism: clinical and experimental. 2022;:155118
Abstract
BACKGROUND Cortisol and corticosterone both circulate in human plasma and, due to differing export by ATP-binding cassette (ABC) transporters, may exert differential cellular effects. ABCB1 (expressed in brain) exports cortisol not corticosterone while ABCC1 (expressed in adipose and skeletal muscle) exports corticosterone not cortisol. We hypothesised that ABCC1 inhibition increases corticosteroid receptor occupancy by corticosterone but not cortisol in humans. METHODS A randomised double-blind crossover study was conducted in 14 healthy men comparing placebo and ABCC1 inhibitor probenecid. Blood sampling, including from veins draining adipose and muscle, was undertaken before and after administration of mineralocorticoid receptor antagonist potassium canrenoate and glucocorticoid receptor antagonist mifepristone (RU486). RESULTS During placebo, systemic plasma cortisol and corticosterone concentrations increased promptly after canrenoate. Cortisol uptake was detected from adipose but not muscle following canrenoate + RU486. Probenecid significantly increased systemic cortisol concentrations, and tended to increase corticosterone and ACTH concentrations, after combined receptor antagonism but had no effects on net glucocorticoid balance in either adipose or muscle. Using quantitative PCR in brain bank tissue, ABCC1 expression was 5-fold higher in human pituitary than hypothalamus and hippocampus. ABCB1 was more highly expressed in hypothalamus compared to pituitary. CONCLUSIONS Although displacement of corticosterone and/or cortisol from receptors in adipose and skeletal muscle could not be measured with sufficient precision to detect effects of probenecid, ABCC1 inhibition induced a greater incremental activation of the hypothalamic-pituitary-adrenal axis after combined receptor blockade, consistent with ABCC1 exporting corticosterone from the pituitary and adding to the evidence that ABC transporters modulate tissue glucocorticoid sensitivity.
2.
The calming effect of roasted coffee aroma in patients undergoing dental procedures.
Pachimsawat, P, Tangprasert, K, Jantaratnotai, N
Scientific reports. 2021;(1):1384
Abstract
Coffee beverage consumption is well-known to exert various health benefits; however, the effects of coffee aroma are rarely explored. This study aimed to investigate the calming effect of inhaling coffee aroma while the patients underwent dental procedures (probing and scaling). Salivary α-amylase (sAA) and cortisol (sCort) levels were measured as proxies of sympathetic nervous system and hypothalamic-pituitary-adrenal axis responses to stress respectively. Blood pressures and pulse rates were recorded. The results showed that undergoing dental procedures could increase sAA and sCort levels of the patients inhaling sham aroma while those inhaling coffee aroma had significantly decreased sAA and sCort levels (40% and 25% differences, respectively). The pulse rates of those inhaling coffee aroma were also lower. Subjective assessment using visual analog scale was in line with objective measures as well. The preference for coffee aroma or the frequency of coffee drinking had no effect on the sAA and sCort responses. This is the first study to provide evidence on the effect of coffee aroma on sAA and sCort levels in patients undergoing dental procedures.
3.
Short-Term d-Aspartic Acid Supplementation Does Not Affect Serum Biomarkers Associated With the Hypothalamic-Pituitary-Gonadal Axis in Male Climbers.
Crewther, B, Witek, K, Draga, P, Zmijewski, P, Obmiński, Z
International journal of sport nutrition and exercise metabolism. 2019;(3):259-264
Abstract
D-aspartic acid (DAA) is promoted as a testosterone (T) enhancing supplement by mechanisms involving the hypothalamic-pituitary-gonadal (HPG) axis. Here, we investigated the short-term effects of DAA on serum biomarkers of the HPG-axis in male climbers. Using a single-blinded, placebo-controlled design, 16 climbers were randomly assigned to either a DAA (3 g/day) or placebo (3 g/day) supplement for 2 weeks. The reverse treatment commenced after a 2-week washout, with all conditions administered in a balanced manner. The subjects maintained their normal weekly training across this study. Serum samples taken before and after each treatment were analyzed for T, luteinizing hormone, sex hormone binding globulin, and cortisol (C), and free T was calculated (cFT). The DAA supplement did not significantly affect serum T, cFT, and luteinizing hormone levels. Only a main effect of time on sex hormone binding globulin (6.8% increase) and C (13.6% decrease) emerged (p < .03). Significant negative associations were identified between pretest values and changes (%) in T, cFT, luteinizing hormone, and C levels with DAA and/or placebo, but these relationships did not differ between treatments (p > .46). Additional measures of physical function and serum hematology also failed to respond to DAA. In summary, a daily dose of DAA during a short training period did not influence T and selected indicators of the HPG-axis in male climbers. Other parameters linked to athletic performance and health status were also unaffected. Our findings support evidence showing that DAA (including DAA-blended supplements) at either recommended or higher dosages does not afford any ergogenic benefits for athletic males.