Acute physical exercise improves recognition memory via locus coeruleus activation but not via ventral tegmental area activation

From gains to gaps? How Selective Androgen Receptor Modulator (SARM) YK11 impact hippocampal function: In silico, in vivo, and ex vivo perspectives

Selective Androgen Receptor Modulators (SARMs), particularly (17α,20E)-17,20-[(1-methoxyethylidene)bis(oxy)]-3-oxo-19-norpregna-4,20-diene-21-carboxylic-acid-methyl-ester (YK11), are increasingly popular among athletes seeking enhanced performance. Serving as an Androgen Receptor (AR) agonist, YK11 stimulates muscle growth while inhibiting myostatin. Our study delved into the impact of YK11 on the rat hippocampus, analyzing potential alterations in neurochemical mechanisms and investigating its synergistic effects with exercise (EXE), based on the strong relationship between SARM users and regular exercise. Utilizing Physiologically Based Pharmacokinetic (PBPK) modeling, we demonstrated YK11 remarkable brain permeability, with molecular docking analysis revealing YK11 inhibitory effects on 5-alpha-reductase type II (5αR2), suggesting high cell bioavailability. Throughout a 5-week experiment, we divided the animals into the following groups: Control, YK11 (0.35 g/kg), EXE (swimming exercise), and EXE + YK11. Our findings showed that YK11 displayed a high binding affinity with AR in the hippocampus, influencing neurochemical function and modulating aversive memory consolidation, including the downregulation of the BDNF/TrkB/CREB signaling, irrespective of EXE combination. In the hippocampus, YK11 increased pro-inflammatory IL-1β and IL-6 cytokines, while reducing anti-inflammatory IL-10 levels. However, the EXE + YK11 group counteracted IL-6 effects and elevated IL-10. Analysis of apoptotic proteins revealed heightened p38 MAPK activity in response to YK11-induced inflammation, initiating the apoptotic cascade involving Bax/Bcl-2/cleaved caspase-3. Notably, the EXE + YK11 group mitigated alterations in Bcl-2 and cleaved caspase-3 proteins. In conclusion, our findings suggest that YK11, at anabolic doses, significantly alters hippocampal neurochemistry, leading to impairments in memory consolidation. This underscore concerns about the misuse risks of SARMs among athletes and challenges common perceptions of their minimal side effects.

Acute physical exercise enhances memory persistence in female rats

Memory is a complex cognitive process with distinct stages, such as acquisition, consolidation, and retrieval. The hippocampus plays a crucial role in memory consolidation and retrieval. Physical exercise (PE) has been shown to enhance memory and cognitive functions, but the available research is mainly developed with males. So, there is limited knowledge about acute PE's effects on females' memory. This study aimed to investigate the impact of acute PE on memory in female rats and explore potential sex differences in PE memory modulation. Forty-two female Wistar rats were subjected to a novel object recognition (NOR) task, with half of them undergoing a single session of 30 min of PE after the learning session (memory acquisition). Behavioral assessments showed that acute PE improved memory persistence in female rats, with increased discrimination of novel objects. Biochemical analysis revealed elevated noradrenaline levels in the hippocampus following acute PE and NOR training. Notably, the positive effects of acute PE on female rats' memory were similar to those previously observed in male rats. These findings suggest that acute PE can enhance memory in female rats and underscore the importance of considering sex differences in cognitive research. PE may offer a non-invasive strategy to promote cognitive health in both males and females.