PSX-A-25 Late-Breaking: The Effects of Chronic Endotoxinemia on Rectal and Subcutaneous Temperature in Wethers

Lipopolysaccharide (LPS) is responsible for inflammation and fever resulting from infections associated with gram-negative bacteria. Twenty-two wethers underwent a chronic LPS challenge in which they were assigned to one of five groups – control (CON; saline IV daily; n=4), single acute dose (SAD; 400 ng/kg bw on D1 and saline D2-7 IV; n=4), daily acute dose (DAD; 400 ng/kg bw IV; n=5), daily increasing dose (DID; 400 ng/kg bw with 20% increase each day IV; n=5), and subcutaneous steady dose (SSD; 20 ug /kg bw per day SQ; n=4). Wethers were equipped with subcutaneous temperature (SCT) sensors (data analyzed hourly; -1 to 148 h) and rectal temperatures (RT) were determined multiple times a day for six days (-1 to 147 h). Two-way ANOVA was completed using SAS v9.4 (Cary, NC) on both the SCT and RT data. There was an effect of treatment, time and an interaction of time and treatment (all P < 0.0001) on RT. Rectal temperature was greater than CON (38.9°C) in SAD (40.5°C), DAD (40.5°C), and DID (40.9°C) groups 3 h after treatment on D1, and the SSD (40.5°C) by 5 h after treatment on D1. While the greatest RT was at 5 h after treatment on D1 for SAD (41.1°C), DAD (41.3°C) and DID (41.8°C) groups. Compared to CON (~38.6°C), RT was increased 3 h after treatment administration on D2 (40.1°C), D3 (39.9°C), D5 (40.1°C), and D6 (39.9°C) for DAD and on D2 (40.1°C) and D5 (39.9°C) for DID. For SCT, there were effects of treatment and time (P < 0.0001), but no interaction (P = 1.00). The SSD group had the greatest SCT (38.3°C) followed by DID (37.7°C), DAD (37.5°C), SAD (37.3°C) and CON (36.9°C). Overall, chronic endotoxin did induce an increase in RT and SCT, but differently with RT changing over time.

Tolerance to neurochemical and behavioral effects of the hallucinogen 25I-NBOMe

Rationale 4-Iodo-2,5-dimethoxy-N-(2-methoxybenzyl)phenethylamine (25I-NBOMe) is a potent serotonin 5-HT2A/2C receptor agonist with hallucinogenic activity. There is no data on the 25I-NBOMe effect on brain neurotransmission and animal performance after chronic administration. Objectives We examined the effect of a 7-day treatment with 25I-NBOMe (0.3 mg/kg/day) on neurotransmitters’ release and rats’ behavior in comparison to acute dose. Methods Changes in dopamine (DA), serotonin (5-HT), acetylcholine (ACh), and glutamate release were studied using microdialysis in freely moving rats. The hallucinogenic activity was measured in the wet dog shake (WDS) test. The animal locomotion was examined in the open field (OF) test, short-term memory in the novel object recognition (NOR) test. The anxiogenic/anxiolytic properties of the drug were tested using the light/dark box (LDB) test. Results Repeated administration of 25I-NBOMe decreased the response to a challenge dose of DA, 5-HT, and glutamatergic neurons in the frontal cortex as well as weakened the hallucinogenic activity in comparison to acute dose. In contrast, striatal and accumbal DA and 5-HT release and accumbal but not striatal glutamate release in response to the challenge dose of 25I-NBOMe was increased in comparison to acute treatment. The ACh release was increased in all brain regions. Behavioral tests showed a motor activity reduction and memory deficiency in comparison to a single dose and induction of anxiety after the drug’s chronic and acute administration. Conclusions Our findings suggest that multiple injections of 25I-NBOMe induce tolerance to hallucinogenic activity and produce alterations in neurotransmission. 25I-NBOMe effect on short-term memory, locomotor function, and anxiety seems to be the result of complex interactions between neurotransmitter pathways.

Effects of Acute Caffeine Intake on Power Output and Movement Velocity During a Multiple-Set Bench Press Exercise Among Mild Caffeine Users

The main goal of this study was to evaluate the effectiveness of an acute dose of caffeine (6 mg/kg body mass (b.m.)) on power output and bar velocity during a bench press multiple-set resistance training session in participants with mild daily caffeine consumption (in the range of 1 to 3 mg/kg/b.m). Thirteen recreationally active male participants (age: 21.9 ± 1.2 years, body mass: 74.4 ± 5.3 kg, body mass index: 23.1 ± 1.6 kg/m2, bench press onerepetition maximum (1RM): 79.2 ± 14.9 kg), with daily caffeine ingestion of 1.56 ± 0.56 mg/kg/b.m., participated in the study with a randomized double-blind experimental design. Each participant performed two identical experimental sessions, 60 min after the intake of a placebo (PLAC) or 6 mg/kg/b.m. of caffeine (CAF-6). In each experimental session, participants performed 5 sets of 5 repetitions of the bench press exercise with a load equivalent to 70% 1RM. The eccentric and concentric phases of the bench press exercise were performed at maximal possible velocity in each repetition. Bar velocity was recorded with a linear position transducer and power output was calculated using velocity and load data. A two-way repeated measures ANOVA indicated no significant substance x set interaction for mean power output (MP), mean bar velocity (MV), peak power output (PP) and peak bar velocity (PV). However, there was a significant main effect of substance on MP (p < 0.01; η2 = 0.47) and MV (p < 0.01; η2 =0.45). Post hoc analysis for main effect revealed that MP and MV values in the CAF-6 group were higher than in the PLAC group in all 5 sets of the exercise (p < 0.05). In conclusion, this study demonstrated that an acute dose of caffeine before resistance exercise increased mean power output and mean bar velocity during a multiple-set bench press exercise protocol among mild caffeine users.

Interaction Between Caffeine and Creatine When Used as Concurrent Ergogenic Supplements: A Systematic Review

There is some controversy regarding the interactions between creatine (CRE) and caffeine (CAF) supplements. The aim of this systematic review was to study whether such ergogenic interaction occurs and to analyze the protocol to optimize their synchronous use. The PubMed, Web of Science, MEDLINE, CINAHL, and SPORTDiscus databases were searched until November 2021 following the PRISMA guidelines. Ten studies were included. Three studies observed that CRE loading before an acute dose of CAF before exercise did not interfere in the beneficial effect of CAF, whereas one study reported that only an acute supplementation (SUP) of CAF was beneficial but not the acute SUP of both. When chronic SUP with CRE + CAF was used, two studies reported that CAF interfered in the beneficial effect of CRE, whereas three studies did not report interaction between concurrent SUP, and one study reported synergy. Possible mechanisms of interaction are opposite effects on relaxation time and gastrointestinal distress derived from concurrent SUP. CRE loading does not seem to interfere in the acute effect of CAF. However, chronic SUP of CAF during CRE loading could interfere in the beneficial effect of CRE.