Unversity of Colima

A significant percentage of depression patients are resistant to pharmacological treatments, highlighting the need for novel antidepressant strategies. Ketamine, an NMDA receptor antagonist, produces rapid antidepressant effects and is effective in treatment-resistant cases, but its association with cognitive and behavioral abnormalities resembling schizophrenia limits broader clinical utility. Capsaicin, a TRPV1 agonist, alone or combined with standard antidepressants, reduces immobility in the forced swim test (FST) in rodents. This study evaluated the effects of capsaicin and ketamine, isolated or combined treatments, in the chronic unpredictable mild stress (CUMS) model using multiple behavioral tests. We found immediate (day 1) and sustained (day 6) synergistic effects of capsaicin and ketamine in the FST after CUMS. The sucrose preference test (SPT) was performed on similar schedule. None of the treatments increased SPT on the last day of CUMS; however, capsaicin, ketamine, and their combination significantly increased SPT on day 6 post-CUMS, though pharmacologically treated groups did not reach SPT values of non-CUMS rats. Capsaicin alone and in combination with ketamine produced anxiolytic-like effects in the elevated plus maze and marble-burying tests. Locomotor activity in the open field test was unaffected by treatments, but all CUMS-exposed groups showed higher activity than non-CUMS animals. The most effective doses of capsaicin or the combination improved body weight and reduced adrenal gland hypertrophy, yet not to non-CUMS levels. These findings indicate that capsaicin plus ketamine exhibits synergistic antidepressant-like effects in the FST, sustains partial SPT recovery post-CUMS, and exerts anxiolytic-like actions.

This study examines how COVID-19 restrictions influenced the location of first sexual intercourse among Mexican university students. The sample included 221 students who initiated sexual activity during the pandemic and 162 who did so before or after. During the pandemic, there was a significant change, with a reduction in sexual relations at parents' houses (from 54.9% to 40.3%) and an increase in first sex in rented/borrowed houses (from 9.3% to 19.5%) and outdoor spaces (from 2.5% to 9.5%). However, at all times, even during pandemic restrictions, the parents' house remained the most common site for first sexual intercourse (46.5%). Other notable locations included hotels/motels (22.7%), rented/borrowed houses (15.1%), cars (9.1%), urban outdoors (3.7%), and rural outdoors (2.9%). Those who first started having sex during the pandemic displayed a lower level of interest in sexual activity (inhibited sexual desire (ISD) score: 3.39 vs 2.64, p = .006), initiated later (17.92 vs 16.95 years, p < .001), and had fewer partners (2.18 vs 2.77, p = .048). These findings highlight the continued importance of the parental home as a key site for first sexual activity among students, but with key shifts in location linked to pandemic restrictions.

The study of photosynthesis and the growth of phytoplankton organisms is important for a better understanding of primary productivity, especially in precursors of harmful algal blooms (HABs), such as the dinoflagellate Lingulaulax polyedra (formerly Lingulodinium polyedra). The effect of nutrient availability (low concentration: 200.3/10.3 μM, medium: 280.5/14.8 μM, and high: 479.7/26.3 μM NaNO₃/NaH₂PO₄) and irradiance (50, 150, 300, and 750 μmol quanta m^-2 s^-1) on the growth rate (μ), photosynthetic efficiency (α), relative electron transport rate (rETR), pigment concentration and absorption coefficient in in vitro cultures of L. polyedra was analyzed. It was observed that μ did not vary with nutrient concentration or irradiance (p > 0.05, AN), and the stationary growth phase was observed in all treatments on day 9 of cultivation. As irradiance increased, significant increase in photoprotective carotenoid pigments and a reduction in photosynthetic pigments were observed among treatments. L. polyedra showed the highest α during the stationary phase in treatments under 50 μmol quanta m^-2 s^-1 irradiance, with a value of 0.259 ± 0.005. Cultures did not show differences between nutrients, suggesting that the species-specific response to light availability depends on the growth phase. This study suggests L. polyedra adjusts its energy use based on irradiance, prioritizing growth in the exponential phase and optimizing photosynthesis for nutrient distribution in the stationary phase. This study contributes to understanding the species' resilience at different irradiances and nutrient concentrations, which can help to understand the adaptations that allow it to potentially form harmful algal blooms (HABs).