Quadriceps and hamstrings prelanding myoelectric activity during landing from different heights among male and female athletes

ACL tear is a major concern among athletes, coaches and sports scientists. More than taking the athlete away from training and competition, ACL tear is a risk factor for early-onset of knee osteoarthritis, and, therefore addressing strategies to avoid such injury is pertinent not only for competitive athletes, but for all physically active subjects. Imbalances in the prelanding myoelectric activity of the hamstrings and quadriceps muscles have been linked to ACL injuries. We investigated the effect of landing from different heights on prelanding myoelectric activity of the hamstrings and quadriceps muscles in recreational athletes. Thirty recreational athletes (15 male and 15 female) performed three bilateral drop jumps from two different heights; 20 cm and 40 cm while myoelectric activity of the vastus medialis, rectus femoris, biceps femoris and medial hamstrings were collected. When increasing the height of drop landing tasks prelanding normalized myoelectric activity of the quadriceps was increased by 15–20% but no significant changes were found for the hamstrings. Female athletes exhibited higher activity of the medial hamstrings compared to their male counterparts. We concluded that increasing the height of drop landing tasks is associated with increased myoelectric activity of the quadriceps but not the hamstrings in recreational athletes. These differences in muscle activity may be related to increased risk for ACL injury when the height is increased. Female athletes demonstrated higher recruitment of the medial hamstrings.     

Effect of ambient temperature on female endurance performance

Ambient temperature can affect physical performance, and an ambient temperature range of −4 °C to 11 °C is optimal for endurance performance in male athletes. The few similar studies of female athletes appear to have found differences in response to cold between the genders. This study investigated whether ambient temperature affects female endurance performance. Nine athletes performed six tests while running on a treadmill in a climatic chamber at different ambient temperatures: 20, 10, 1, −4, −9 and −14 °C and a wind speed of 5 m s⁻¹. The exercise protocol consisted of a 10-min warm-up, followed by four 5-min intervals at increasing intensities at 76%, 81%, 85%, and 89% of maximal oxygen consumption. This was followed by an incremental test to exhaustion. Although peak heart rate, body mass loss, and blood lactate concentration after the incremental test to exhaustion increased as the ambient temperature rose, no changes in time to exhaustion, running economy, running speed at lactate threshold or maximal oxygen consumption were found between the different ambient temperature conditions. Endurance performance during one hour of incremental exercise was not affected by ambient temperature in female endurance athletes.     

Sex differences in leg dexterity are not present in elite athletes

We studied whether the time-varying forces that control unstable foot–ground interactions provide insight into the neural control of dynamic leg function. Twenty elite (10 F, 26.4 ± 3.5 yrs) and 20 recreational (10 F, 24.8 ± 2.4 yrs) athletes used an isolated leg to maximally compress a slender spring designed to buckle at low forces while seated. The foot forces during the compression at the edge of instability quantify the maximal sensorimotor ability to control dynamic foot–ground interactions. Using the nonlinear analysis technique of attractor reconstruction, we characterized the spatial (interquartile range IQR) and geometric (trajectory length TL, volume V, and sum of edge lengths SE) features of the dynamical behavior of those force time series. ANOVA confirmed the already published effect of sex, and a new effect of athletic ability, respectively, in TL (p = 0.014 and p < 0.001), IQR (p = 0.008 and p < 0.001), V (p = 0.034 and p = 0.002), and SE (p = 0.033 and p < 0.001). Further analysis revealed that, for recreational athletes, females exhibited weaker corrective actions and greater stochasticity than males as per their greater mean values of TL (p = 0.003), IQR (p = 0.018), V (p = 0.017), and SE (p = 0.025). Importantly, sex differences disappeared in elite athletes. These results provide an empirical link between sex, athletic ability, and nonlinear dynamical control. This is a first step in understanding the sensorimotor mechanisms for control of unstable foot–ground interactions. Given that females suffer a greater incidence of non-contact knee ligament injuries, these non-invasive and practical metrics of leg dexterity may be both indicators of athletic ability, and predictors of risk of injury.     

Effects of competition outcome on testosterone concentrations in humans: An updated meta-analysis

A contribution to a special issue on Hormones and Human Competition.Since Archer's (2006) influential meta-analysis, there has been a major increase in the number of studies investigating the effect of competition outcome on testosterone reactivity patterns in humans. Despite this increased research output, there remains debate as to whether competition outcome modulates testosterone concentrations. The present paper examines this question using a meta-analytic approach including papers published over the last 35 years. Moreover, it provides the first meta-analytic estimate of the effect of competition outcome on testosterone concentrations in women. Results from a meta-analysis involving 60 effect sizes and > 2500 participants indicated that winners of a competition demonstrated a larger increase in testosterone concentrations relative to losers (D = 0.20)—an effect that was highly heterogeneous. This ‘winner-loser’ effect was most robust in studies conducted outside the lab (e.g., in sport venues) (D = 0.43); for studies conducted in the lab, the effect of competition outcome on testosterone reactivity patterns was relatively weak (D = 0.08), and only found in studies of men (D = 0.15; in women: D = − 0.04). Further, the 'winner-loser' effect was stronger among studies in which pre-competition testosterone was sampled earlier than (D = 0.38, after trim and fill correction) rather than within (D = 0.09) 10 min of the start of the competition. Therefore, these results also provide important insight regarding study design and methodology, and will be a valuable resource for researchers conducting subsequent studies on the 'winner loser' effect.     

Severe preeclampsia: Association of genes polymorphisms and maternal cytokines production in Brazilian population

IntroductionPreeclampsia (PE) is a multi-system disorder of pregnancy characterized by hypertension and proteinuria. Healthy pregnancy is associated with a controlled inflammatory process, which is exacerbated in PE in response to excessive placental stimuli. Gene expression levels can affect inflammation and immune regulation. It is known that differences in cytokine allele frequencies amongst populations may contribute to difference in the incidence of several diseases.ObjectiveThe aim of this study was to investigate the frequency of TNF-α, IL-6, IFN-γ and IL-10 genes polymorphisms and their relationship with the cytokines plasma levels in PE.MethodsA total of 281 women were included in this study; 116 with severe PE, 107 normotensive pregnant and 58 non-pregnant women. Cytokine genotyping was carried out by the polymerase chain reaction. The analyzed polymorphisms were: TNF-α (−308 G → A), IL-10 (−1082 G → A), IL-6 (−174 G → C), and IFN-γ (+874 A → T). Cytokine plasma levels were measured by Cytometric Bead Array method.ResultsA higher frequency of the IFN-γ (+874) T/T genotype in severe PE comparing to normotensive pregnant women was found (P < 0.001). TNF-α, IL-6 and IFN-γ plasma levels were higher in PE women compared to non-pregnant women (P < 0.001; P < 0.001; P = 0.004). IL-6 and IFN-γ levels were also higher in PE women compared to normotensive pregnant (P < 0.001; P = 0.010). IL-10 levels were higher in normotensive pregnant women compared to PE (P < 0.001). IFN-γ and IL-6 genes polymorphisms influenced the genic expression in PE and normotensive pregnant women, respectively.ConclusionsThese results suggest that IFN-γ seems to play a role in PE occurrence.     

Distribution and survival of faecal indicator bacteria in the sediments of the Bay of Vidy,Lake Geneva,Switzerland

The purpose of this study was to determine the concentrations and the horizontal distribution of faecal indicator bacteria (FIB) including Escherichia coli and Enterococcus sp. in the bottom sediments of the Bay of Vidy, City of Lausanne, Switzerland. A vertical distribution of FIB in sediments near the municipal wastewater treatment plant (WWTP) outlet was evaluated and their persistence in those sediments was monitored for a period of 90 days. High FIB levels were measured in the sediments sampled near the WWTP outlet pipe and the mouth of the Chamberonne River, at concentrations ranging between 10⁵ and 10⁷ CFU 100 g^?1. FIB levels at 10 cm depth in the sediments near the WWTP outlet pipe ranged between 10⁴ and 10⁵ CFU 100 g^?1, and were still detected in the top 6 cm after 90 days. Results of this study indicate that freshwater sediments of the Bay of Vidy constitute a reservoir of faecal indicator bacteria, which can persist in certain areas of the bay. Possible resuspension of FIB and pathogens may affect water quality and may increase health risks to sensitive populations during recreational activities. FIB survival in sediments for long periods is of considerable significance for the understanding of microbial pollution in water and for the management of risk at specific recreational coastal sites.     

Predictive value of cystatin C and beta-2 microglobulin in preeclampsia

The purpose of this study was to determine whether the levels of cystatin C and beta-2 microglobulin (B2M) are altered during the second trimester in the plasma of women who subsequently develop preeclampsia.Study designWe performed a case control study to compare the levels of cystatin C and B2M in women in whom preeclampsia ultimately developed (n = 30) and in pregnant women who remained normotensive throughout gestation (n = 60). The maternal plasma levels of cystatin C and B2M were measured by enzyme-linked immunosorbent assay. Blood samples were collected between 15 and 20 weeks’ gestation for fetal aneuploidy screening and frozen at ?20 °C until assay after groups had been selected.ResultsThe median concentrations of cystatin C and B2M were significantly higher in those who subsequently developed preeclampsia when compared to those of normal pregnancy (median 668.6 ng/ml and 418.3 μg/ml vs 413.7 ng/ml and 321.2 μg/ml, respectively).ConclusionsIn this study, the maternal plasma levels of cystatin C and B2M were significantly elevated in pregnant women who subsequently developed preeclampsia as compared with normotensive women. Alterations of these proteins antedate clinical symptoms and, thus, they may be useful for early identification of patients at the risk of developing preeclampsia.     

Reliability and validity of skin temperature measurement by telemetry thermistors and a thermal camera during exercise in the heat

New technologies afford convenient modalities for skin temperature (T_SKIN) measurement, notably involving wireless telemetry and non-contact infrared thermometry. The purpose of this study was to investigate the validity and reliability of skin temperature measurements using a telemetry thermistor system (TT) and thermal camera (TC) during exercise in a hot environment. Each system was compared against a certified thermocouple, measuring the surface temperature of a metal block in a thermostatically controlled waterbath. Fourteen recreational athletes completed two incremental running tests, separated by one week. Skin temperatures were measured simultaneously with TT and TC compared against a hard-wired thermistor system (HW) throughout rest and exercise. Post hoc calibration based on waterbath results displayed good validity for TT (mean bias [MB]=−0.18 °C, typical error [TE]=0.18 °C) and reliability (MB=−0.05 °C, TE=0.31 °C) throughout rest and exercise. Poor validity (MB=−1.4 °C, TE=0.35 °C) and reliability (MB=−0.65 °C, TE=0.52 °C) was observed for TC, suggesting it may be best suited to controlled, static situations. These findings indicate TT systems provide a convenient, valid and reliable alternative to HW, useful for measurements in the field where traditional methods may be impractical.     

Cortisol and testosterone associations with social network dynamics

This study integrates behavioral endocrinology and network science to explore links between hormones and social network dynamics. Specifically, we examine how cortisol (C) and testosterone (T) are associated with creation of new friendships and maintenance of existing friendships. A collegiate marching band was used as a model system of a mixed-sex social organization. Participants (n = 193; 53% female; M age = 19.4 years, 62.1% European-American) provided friendship nominations at time 1 and two months later at time 2. At time 1, participants donated saliva before and after rehearsal (later assayed for C and T). Stochastic actor-based models revealed that individuals with higher C levels were less likely to maintain their social relationships and more likely to create new friendships. In contrast, individuals with higher T levels were more likely to maintain friendships and less likely to create new relationships. Findings suggest that individual differences in C and T are associated with the initiation and maintenance of friendships and have several noteworthy theoretical implications.     

Brain natriuretic peptide predicts forced vital capacity of the lungs,oxygen pulse and peak oxygen consumption in physiological condition

Brain natriuretic peptide (NT-pro-BNP) is used as marker of cardiac and pulmonary diseases. However, the predictive value of circulating NT-pro-BNP for cardiac and pulmonary performance is unclear in physiological conditions. Standard echocardiography, tissue Doppler and forced spirometry at rest were used to assess cardiac parameters and forced vital capacity (FVC) in two groups of athletes (16 elite male wrestlers (W), 21 water polo player (WP)), as different stress adaptation models, and 20 sedentary subjects (C) matched for age. Cardiopulmonary test on treadmill (CPET), as acute stress model, was used to measure peak oxygen consumption (peak VO2), maximal heart rate (HRmax) and peak oxygen pulse (peak VO2/HR). NT-pro-BNP was measured by immunoassey sandwich technique 10 min before the test – at rest, at the beginning of the test, at maximal effort, at third minute of recovery. FVC was higher in athletes and the highest in W (WP 5.60 ± 0.29 l; W 6.57 ± 1.00 l; C 5.41 ± 0.29 l; p < 0.01). Peak VO2 and peak VO2/HR were higher in athletes and the highest in WP. HRmax was not different among groups. In all groups, NT-pro-BNP decreased from rest to the beginning phase, increased in maximal effort and stayed unchanged in recovery. NT-pro-BNP was higher in C than W in all phases; WP had similar values as W and C. On multiple regression analysis, in all three groups together, ΔNT-pro-BNP from rest to the beginning phase independently predicted both peak VO2 and peak VO2/HR (r = 0.38, 0.35; B = 37.40, 0.19; p = 0.007, 0.000, respectively). NT-pro-BNP at rest predicted HRmax (r = −0.32, B = −0.22, p = 0.02). Maximal NT-pro-BNP predicted FVC (r = −0.22, B = −0.07, p = 0.02). These results show noticeable predictive value of NT-pro-BNP for both cardiac and pulmonary performance in physiological conditions suggesting that NT-pro-BNP could be a common regulatory factor coordinating adaptation of heart and lungs to stress condition.     

Assessment of gender-related differences in vitamin D levels and cardiovascular risk factors in Saudi patients with type 2 diabetes mellitus

Diabetes is a major risk factor for cardiovascular disease (CVD) including stroke, coronary heart disease, and peripheral artery disease. It remains a leading cause of mortality throughout the world, affecting both women and men. This investigation was aimed to study gender based differences in cardiovascular risk factors of adult population with type-2 diabetes mellitus (T2DM) and to check the correlation between serum HbA1C, lipid profile and serum vitamin D levels, in T2DM patients of Riyadh, Saudi Arabia. This hospital-based cross-sectional study involving subjects was divided into two gender based groups; normal male (800), diabetic male (800) and normal female (800) and T2DM females (800). Blood samples were analyzed for fasting glucose (FBG), HbA1c, total cholesterol (TC), triglycerides (Tg), low density lipoprotein cholesterol (LDL-C), high density lipoprotein cholesterol (HDL-C) and serum levels of 25(OH)-vitamin D in all groups. All the glycemic control parameters and lipid profile parameters were found to be significantly different in diabetic vs non-diabetic group (p < 0.001) in both genders. The results also show that vitamin D concentration decreased significantly (p < 0.001) in diabetic patients than the healthy individuals in both the genders. Vitamin-D and HbA1C were negatively correlated in both males and females in T2DM patients and significant at P < 0.05. Our study reveals that dyslipidemia remains one of the major risk factors of CVD in T2DM. In addition to dyslipidemia, decreased levels of vitamin-D associated with increased HbA1C alarms the early diagnosis of Type 2 Diabetes.     

Ingesta de yodo durante el embarazo: efectos en la función tiroidea materna y neonatal

IntroductionRecent studies in Spain have shown an inadequate iodine intake in a significant proportion of pregnant women. Pregnancy increases thyroid hormone requirements, and adequate iodine intake is therefore needed.Material and methodsOne hundred and forty-seven women in their third trimester (week 37) of pregnancy provided a blood sample and a 24-hour urine sample to test serum and urine iodine levels and completed a food frequency questionnaire to assess iodine intake during pregnancy. Serum TSH levels were measured in the babies born to the 140 mothers in the postpartum group.ResultsOnly 10.9% of pregnant women consumed more than 250 μg iodine daily, and 24.4% of them consumed less than 100 μg daily. Mean free T4 levels were 9.37 pmol/L, and 74 women (54.41%) had levels below the hypothyroxinemia threshold. TSH levels were normal in 135 newborns (96.4%), while 5 (3.6%) had levels higher than 5 μU/mL.     

Plasma renin and aldosterone levels in obese and non-obese women with polycystic ovary syndrome

ObjetiveTo assess plasma renin and aldosterone levels in obese and non-obese women with polycystic ovary syndrome (PCOS).MethodsObese women (body mass index [BMI] > 30 kg/m2; group A, n = 34) and non-obese women (BMI < 25 kg/m2; group B, n = 13) with PCOS were selected. The control group (group C, n =47) consisted of age-matched women with regular menses and normal ultrasonographic ovaries. Luteinizing hormone, follicle-stimulating hormone, androstenedione, testosterone, sex hormone-binding globulin, serum glucose, insulin, renin, plasma renin activity, and aldosterone levels were measured.ResultsObese and non-obese women with PCOS had higher luteinizing hormone, follicle-stimulating hormone, androstenedione, testosterone, and insulin levels as compared to women in the control group (p < 0.05). Women with PCOS had significantly higher renin levels (group A: 50.2 ± 4.9 picoU/mL, group B: 39.9 ± 2.7 picoU/mL, and group C: 24.6 ± 2.6 picoU/mL), plasma renin activity (group A: 3.7 ± 0.3 ng/mL/h, group B: 3.6 ± 0.3 ng/mL/h, and group C: 2.2 ± 0.4 ng/mL/h), and aldosterone levels (group A: 31.2 ± 3.3 ng/dL, group B: 29.3 ± 2.9 ng/dL, and group C: 22.2 ± 3.9 ng/dL) as compared with controls.ConclusionSignificant differences exist in plasma renin and aldosterone levels between obese and non-obese women as compared with polycystic ovary syndrome and normal controls.     

Serum cytokines and muscle strength after anterior cruciate ligament surgery are not modulated by high-doses of vitamins E (α- and γ-tocopherol’s) and C

The purpose of this investigation was to identify if supplemental vitamin E (consisting of α- and γ-tocopherol’s) and C modulate serum cytokine and muscle strength following an ACL injury and surgery. Subjects were randomly assigned to one of two groups: (1) placebo (n = 14) or (2) vitamins E (α-[600 mg RRR-α-tocopherol, αT] and γ-[600 mg of RRR-γT]) and C (1000 mg ascorbic acid, AA) (EC; n = 15). Supplements were taken daily starting ∼2-wk prior to and concluding 16-wk after surgery. Fasting blood samples were obtained and single-leg peak isometric force measurements were performed at baseline (prior to supplementation), before surgery (∼120-min – blood draw only), and 8-wk, 12-wk, and 16-wk after surgery. αT, γT, AA, and cytokines were measured in each blood sample, and peak isometric force was measured on the injured and non-injured legs separately at each testing session. An exercise protocol consisting of repetitive knee and hip extension and flexion contractions to exhaustion was performed on the injured limb at 16-wk. Vitamin E and C supplementation significantly (all p < 0.05) increased plasma αT (∼40%), γT (∼160%), and AA (∼50%) concentrations. Serum cytokine concentrations, peak isometric force, and time to exhaustion during the exercise protocol were not significantly different between groups. Based on these findings, we conclude that vitamin E and C supplementation increases their endogenous levels without minimizing muscular weakness or modulating serum cytokine concentrations after ACL surgery.     

Effect of temperature and host species on parasitism,development time and sex ratio of the egg parasitoid Trichogrammatoidea lutea Girault (Hymenoptera: Trichogrammatidae)

The developmental biology of Trichogrammatoidea lutea Girault (Hymenoptera: Trichogrammatidae) was studied at six constant temperatures (18, 21, 24, 27, 30 and 35 °C) on eggs of three lepidopteran host species: Helicoverpa armigera (Hübner) (Noctuidae), Chilo partellus (Swinhoe) (Crambidae) and Cadra cautella (Walker) (Pyralidae). T. lutea did not complete development at 35 °C on any of the three host species. Parasitism levels were highest on H. armigera at 27 °C (58%), C. cautella at 27 and 30 °C (31% and 28%) and C. partellus between 24 and 30 °C (13–17%). Realized progeny of T. lutea per parasitized host egg was influenced by host size. The number of progeny of T. lutea per parasitized host egg was highest on H. armigera, followed by C. partellus and lowest on C. cautella. The sex ratio was female biased on C. partellus, female biased on C. cautella with the exception of 21 °C and close to 1:1 on H. armigera. The rate of development from egg to pupa and egg to adult was fastest on H. armigera and slowest on C. partellus. Lower thresholds for development and degree days (DD) of T. lutea from egg to adult were 12.8 °C and 105.4 DD on H. armigera, 11.3 °C and 141.6 DD on C. partellus and 12.9 °C and 118.2 DD on C. cautella, respectively. Based on these results, H. armigera is the most suitable host for mass rearing of T. lutea for biological control of Lepidoptera pests because of the relatively high parasitism levels, short development time, greater clutch size and balanced sex ratio. C. cautella may also be used although longer exposure times might be required due to lower parasitism levels.     

Comparison between ambulatory measurement of effective thermal conductivity and laser Doppler flowmetry method to assess skin microcirculatory activity

The main objective of this paper was to assess the performance of the ambulatory device μHematron to measure indirectly skin blood flow relative to the well-established Laser Doppler flowmetry method. The μHematron device is dedicated to the non-invasive measurement of effective thermal conductivity of living tissues, based on the thermal clearance method. Its major advantage is its ambulatory functionality, as available methods for evaluation of microcirculatory activity are non-ambulatory methods. An experiment was conducted on ten healthy women exposed for one hour in three different thermal environments (22 °C, 25 °C and 30 °C). Skin microcirculatory activity was analyzed after an acclimatization period of 30 minutes. The time between each exposure was at least one hour. Performances of the μHematron device were assessed and a comparative study with a laser Doppler perfusion monitor (LDPM) was performed. Good correlation coefficients between the two devices (r = 0.71 at T1 = 22 °C, r = 0.77 at T2 = 25 °C and r = 0.83 at T3 = 30 °C) were obtained while the LDPM signal was filtered by a low pass filter (0.1 Hz). These results showed that continuous monitoring of effective thermal conductivity was possible in neutral and warm ambiences. Then, the μHematron device could be considered as a complementary tool to Doppler techniques for the investigation of skin blood flow, when ambulatory conditions are required.     

Effects of constant temperature,exposure period,and age on diapause induction in Trichogramma dendrolimi

Trichogramma dendrolimi can be successfully reproduced in fresh eggs dissected from ovaries of the Chinese tussah silkworm (Antheraea pernyi) and is widely used in biological control of lepidopteran agricultural and forest pests in China. Diapause induction of T. dendrolimi in A. pernyi eggs was investigated through exposing the parasitoid to six constant temperatures (16, 13, 10, 7, 4, and 1 °C) for 19 exposure periods between 10 and 46 days. The sensitive age of T. dendrolimi for diapause induction was explored through a separate experiment to examine the parasitoids that had developed for 2, 3, 4, 5, 6, 7, and 8 days at 26 °C after parasitization, under the six constant temperatures, respectively. Diapause was induced at 10 or 7 °C, and the induction period was 4–6 weeks. The sensitive age of T. dendrolimi to react at the induction temperature was 2–3 days (at 26 °C). At 7 and 10 °C, the diapause rate increased with increasing exposure period and decreased with increased T. dendrolimi age at exposure. The optimum method to induce diapause in T. dendrolimi consisted of exposing hosts for parasitization at 26 °C for 8 h, and then keeping them at 26 °C for 40 h, finally, moving them into 10 °C for 4 weeks.     

Testosterone and androgen receptor gene polymorphism are associated with confidence and competitiveness in men

A contribution to a special issue on Hormones and Human Competition.Studies in non-human animals and humans have demonstrated the important role of testosterone in competitive interactions. Here, we investigated whether endogenous testosterone levels predict the decision to compete, in a design excluding spite as a motive underlying competitiveness. In a laboratory experiment with real monetary incentives, 181 men solved arithmetic problems, first under a noncompetitive piece rate, followed by a competition incentive scheme. We also assessed several parameters relevant to competition, such as risk taking, performance, and confidence in one's own performance. Salivary testosterone levels were measured before and 20 min after the competition task using mass spectrometry. Participants were also genotyped for the CAG repeat polymorphism of the androgen receptor gene, known to influence the efficacy of testosterone signaling in a reciprocal relationship to the number of CAG repeats. We observed a significant positive association between basal testosterone levels and the decision to compete, and that higher testosterone levels were related to greater confidence in one's own performance. Whereas the number of CAG repeats was not associated with the choice to compete, a lower number of CAG repeats was related to greater confidence in those who chose to compete, but this effect was attributable to the polymorphism's effect on actual performance. An increase in testosterone levels was observed following the experiment, and this increase varied with self-reported high-school math grades. We expand upon the latest research by documenting effects of the androgen system in confidence in one's own ability, and conclude that testosterone promotes competitiveness without spite.     

The impact of scopolamine pretreatment on 3-iodothyronamine (T1AM) effects on memory and pain in mice

We previously demonstrated that 3-iodothyronamine (T1AM), a by-product of thyroid hormone metabolism, pharmacologically administered to mice acutely stimulated learning and memory acquisition and provided hyperalgesia with a mechanism which remains to be defined. We now aimed to investigate whether the T1AM effect on memory and pain was maintained in mice pre-treated with scopolamine, a non-selective muscarinic antagonist expected to induce amnesia and, possibly, hyperalgesia.Mice were pre-treated with scopolamine and, after 20 min, injected intracerebroventricularly (i.c.v.) with T1AM (0.13, 0.4, 1.32 μg/kg). 15 min after T1AM injection, the mice learning capacity or their pain threshold were evaluated by the light/dark box and by the hot plate test (51.5 °C) respectively. Experiments in the light/dark box were repeated in mice receiving clorgyline (2.5 mg/kg, i.p.), a monoamine oxidase (MAO) inhibitor administered 10 min before scopolamine (0.3 mg/kg).Our results demonstrated that 0.3 mg/kg scopolamine induced amnesia without modifying the murine pain threshold. T1AM fully reversed scopolamine-induced amnesia and produced hyperalgesia at a dose as low as 0.13 μg/kg. The T1AM anti-amnestic effect was lost in mice pre-treated with clorgyline.We report that the removal of muscarinic signalling increases T1AM pro learning and hyperalgesic effectiveness suggesting T1AM as a potential treatment as a “pro-drug” for memory dysfunction in neurodegenerative diseases.