Serum bone metabolism biomarkers in healthy filies and colts from weaning until one year of age.

This study aimed to investigate the serum concentration of osteocalcin (OC), parathyroid hormone (PTH), calcitonin (CT), calcium (Ca), phosphorus (P), alkaline phosphatase (ALP) and acid phosphatase (AP) in healthy-weaned-foals from 8 months of age until the first year of life. Moreover, the correlation of investigated parameters and foals' age, as well as the relationship between the serum values of PTH and the other markers of bone remodeling were assessed. From 20 foals (10 fillies, 10 colts), blood samples were monthly collected (from 8 to 12 months of age, T1-T5) and the concentration of OC, CT, Ca, P, ALP, AP and PTH was assessed. Two-way repeated measures analysis of variance (ANOVA) showed age-related differences on OC concentration in both fillies (P = 0.008) and colts (P = 0.03) with higher OC values at T5 than T1 and T2. Sex-related effect on OC concentration was found with higher OC levels in colts compared to fillies (P = 0.01). A significant positive correlation between the OC, PTH, CT and APL values and foal's age was found in fillies and colts. PTH levels were positively correlated with the values of OC in fillies and colts. Obtained findings confirmed the dynamic bone turnover during growth in foals. The modification of PTH and OC confirmed the potential role of these parameters as indicator of bone growth and metabolism. The sex-related difference observed in OC concentration opens up new insights into the possible involvement of sex hormones in the regulation of bone metabolism in prepubertal foals.

Physiological Correlation between Hypothalamic-Pituitary-Adrenal Axis, Leptin, UCP1 and Lipid Panel in Mares during Late Pregnancy and Early Postpartum Period.

This study aimed to investigate the dynamic change of adrenocorticotrophic hormone (ACTH), cortisol, leptin, mitochondrial uncoupling protein 1 (UCP1), lipids and lipoproteins in mares during late pregnancy and the postpartum period. A total of 20 mares (10 pregnant mares, monitored from 14 ± 2 days before expected foaling until 14 days after foaling, Group A; 10 non-pregnant and non-lactating mares, Group B) were enrolled in the study. Body Condition Score (BCS) and body weight (BW) values were recorded from each animal. In Group A, blood samples were collected on days 14 ± 2 and 7 ± 2 before foaling (T-14; T-7), and on days 7 and 14 after foaling (T+7; T+14). From mares of Group B, blood samples were collected at the beginning of the study. The levels of ACTH, cortisol, leptin, UCP1, non-esterified fatty acids (NEFAs), total cholesterol, high-density lipoproteins (HDLs), low-density lipoproteins (LDLs), triglycerides and very-low-density lipoproteins (VLDLs) were investigated. While BCS showed no statistical change throughout the monitoring period (p > 0.05), all the other studied parameters displayed statistically significant variations in Group A over the peripartum period (p < 0.0001). A significant effect of pregnancy was found on all studied parameters (p < 0.001). The ACTH and cortisol levels measured in mares belonged to Group A showed a significant positive correlation with the values of leptin, LDLs, triglycerides and VLDLs, whereas they were negatively correlated with the serum UCP1 and NEFAs values. Together, the findings gathered in this study highlight a dynamic change of serum leptin, UCP1 and lipid parameters in peripartum mares and suggest an interaction of the HPA axis with lipid metabolism and mobilization in mares during the peripartum period in order to deal with metabolic and energy demand and maintain energy homeostasis.

Dynamic Change of Serum Levels of Some Branched-Chain Amino Acids and Tryptophan in Athletic Horses After Different Physical Exercises.

Physical exercise induces several adaptations involving modulation of the energetic pathways to meet the energy demand during physical exercise. The branched-chain amino acids, leucine in particular, are considered as the most relevant amino acids, especially for exercise physiology. In this study, the change of leucine, valine, and tryptophan concentration was investigated in athletic horses before and after different exercise type. A total of 40 sport horses were equally divided into 4 groups according to the exercise type: group A (jumping), group B (reining), group C (32 km ride), and group D (72 km ride). Blood samples were collected before (TPRE), immediately after (TPOST), and 30 minutes after (TPOST30) the race to assess leucine, valine, and tryptophan concentration. Two-way analysis of variance showed an effect of time and/or exercise on the serum leucine, valine, and tryptophan values in all groups (P < .01). Lower leucine and valine values were found in groups A, B, and D at TPOST and TPOST30 respect to TPRE, whereas group C showed higher values at TPOST and TPOST30 compared with the values found at TPRE. All groups showed increased tryptophan values at TPOST and TPOST30 compared with TPRE. Lower leucine, valine, and tryptophan values were found in group D at TPOST30 compared with the values found at TPOST. These dynamic changes suggest the involvement of amino acid metabolism during different exercise types. These findings are probably related to the complex physiological adaptations to exercise stressor that allow reestablishment of the homeostatic equilibrium of the organism.

Serum muscle-derived enzymes response during show jumping competition in horse.

AIM: The effect of two jumping competitions, performed in two consecutive weekends, on serum creatine phosphokinase (CPK), aspartate aminotransferase (AST), and lactate dehydrogenase (LDH), urea, creatinine (CREA) concentrations were evaluated in 12 healthy jumper horses. MATERIALS AND METHODS: Blood sampling was performed before the 1(st) day of competition (T0), at the end of each show (J1, J2), on the day after the competition (T1); the same sampling plan was followed during the second weekend (J3, J4 and T2). RESULTS: One-way repeated measures analysis of variance showed an increase in CPK at J1 and J2 respect to T0 and at J3 and J4 respect to all other time points (p<0.05). LDH activity showed an increase at J2 respect to T0, at J3 respect to T0, J1, J2 and at J4 respect to all other time points (p<0.05). AST values increased at J1 and J2 respect to T0 (p<0.05). A significant increase of CREA was found at J3 respect to T0, T1 and J1 and at J4 respect to all other time points (p<0.05). A decrease in serum urea levels was found at J1 respect to T0, at J2 and J4 respect to T0 and T1; at T2 respect to T0 (p<0.05). A positive correlation between urea/CPK (p=0.0042, r(2)=0.030), LDH/CPK (p<0.0001, r(2)=0.535), CREA/LDH (p<0.0001, r(2)=0.263), CREA/CPK (p<0.0001, r(2)=0.496) was observed. CONCLUSION: Our results suggest that 5 days recovery period between the two consecutive competition weekends is insufficient to allow muscle recovery and avoid potential additional stress. The findings obtained in this study improve the knowledge about metabolic changes occurring in athlete horse during the competition to identify muscle alterations following show jumping competitions.

Impact of an acoustic stimulus on the motility and blood parameters of European sea bass (Dicentrarchus labrax L.) and gilthead sea bream (Sparus aurata L.).

The physiological responses of fish to underwater noise are poorly understood and further information is needed to evaluate any possible negative effects of sound exposure. We exposed European sea bass and gilthead sea bream to a 0.1-1 kHz linear sweep (150 dB(rms) re 1 microPa). This band frequency is perceptible by many species of fish and is mainly produced by vessel traffic. We assessed the noise-induced motility reaction (analysing the movements) and the haematological responses (measuring blood glucose and lactate, and haematocrit levels). The noise exposure produced a significant increase in motility as well as an increase in lactate and haematocrit levels in sea bream and sea bass. A significant decrease of glucose was only observed in sea bream. A linear correlation between blood parameters and motility in fish exposed to the noise was observed. The acoustic stimulus produced intense muscle activity.

Influence of time of day on body temperature, heart rate, arterial pressure, and other biological variables in horses during incremental exercise.

We examined the response to exercise of selected physiological variables in horses performing the identical routine for eight days, in the morning (a.m.) or in the afternoon (p.m.). Heart rate (HR), systolic and diastolic blood pressure (BP), and body temperature (BT) were all consistently greater in the p.m. For BP and BT, the absolute increase above the a.m. values was the same at rest and during exercise. For HR, the absolute increase was greater during exercise, but the percent increase was the same as during rest. During exercise, blood glucose decreased, while blood lactate and skin temperature increased; these changes were the same during the a.m. and p.m. sessions. We conclude that there is no indication in horses of a difference in the responses of HR, BP, and BT to exercise between the a.m. and p.m. The circadian oscillations, however, alter the absolute values of these variables both at rest and during exercise, raising the possibility that the safety margins against hyperthermia and hypertension may decrease during p.m. exercise.

Chronobiologic blood pressure assessment: maturation of the daily rhythm in newborn foals.

Circadian rhythmicity of physiological processes in animals has been described for some variables. In order to investigate the daily rhythmicity of blood pressure, seven foals (Equus caballus) were used for 40 days after birth. Measurements of blood pressure were done by means of an oscillometric apparatus (Argus TM-7, Schiller, Barr Switzerland) with the foals in a standing position and the cuff placed around the tail. Blood pressure was recorded twice a day, 1 hour before dawn and 1 hour before dusk for the first 10 days of life, every 2 days from the 11th to the 32nd day, on the 36th and on the 40th day. Two-way repeated measures analysis of variance (ANOVA) were used to determine statistically significant differences between the mean values recorded at dawn and dusk during the study. Analysis of variance showed a significant effect of time (p<0.0001), during the first 40 days of life. This study confirms a strong correlation between age and blood pressure in horse and the absence of blood pressure maturation in foals 40 days old. The results on the maturation of the daily rhythm of blood pressure in foals is a contribution to the study of the development of circadian rhythms in mammals. These results are also useful for the chronophysiological assessment of blood pressure in the horse.

Chronobiologic blood pressure assessment: Maturation of the daily rhythm in newborn foals

Circadian rhythmicity of physiological processes in animals has been described for some variables. In order to investigate the daily rhythmicity of blood pressure, seven foals (Equus caballus) were used for 40 days after birth. Measurements of blood pressure were done by means of an oscillometric apparatus (Argus TM-7, Schiller, Barr Switzerland) with the foals in a standing position and the cuff placed around the tail. Blood pressure was recorded twice a day, 1 hour before dawn and 1 hour before dusk for the first 10 days of life, every 2 days from the 11th to the 32nd day, on the 36th and on the 40th day. Two-way repeated measures analysis of variance (ANOVA) were used to determine statistically significant differences between the mean values recorded at dawn and dusk during the study. Analysis of variance showed a significant effect of time (p<0.0001), during the first 40 days of life. This study confirms a strong correlation between age and blood pressure in horse and the absence of blood pressure maturation in foals 40 days old. The results on the maturation of the daily rhythm of blood pressure in foals is a contribution to the study of the development of circadian rhythms in mammals. These results are also useful for the chronophysiological assessment of blood pressure in the horse.

Central fatigue and nycthemeral change of serum tryptophan and serotonin in the athletic horse.

BACKGROUND: The serotonergic system is associated with numerous brain functions, including the resetting of the mammalian circadian clock. The synthesis and metabolism of 5-HT in the brain increases in response to exercise and is correlated with high levels of blood-borne tryptophan (TRP). The present investigation was aimed at testing the existence of a daily rhythm of TRP and 5-HT in the blood of athletic horses. METHODS: Blood samples from 5 Thoroughbred mares were collected at 4-hour intervals for 48 hours (starting at 08:00 hours on day 1 and finishing at 4:00 on day 2) via an intravenous cannula inserted into the jugular vein. Tryptophan and serotonin concentrations were assessed by HPLC. Data analysis was conducted by one-way repeated measures analysis of variance (ANOVA) and by the single cosinor method. RESULTS: ANOVA showed a highly significant influence of time both on tryptophan and on serotonin, in all horses, on either day, with p values < 0.0001. Cosinor analysis identified the periodic parameters and their acrophases (expressed in hours) during the 2 days of monitoring. Both parameters studied showed evening acrophases. CONCLUSION: The results showed that serotonin and tryptophan blood levels undergo nycthemeral variation with typical evening acrophases. These results enhance the understanding of the athlete horse's chronoperformance and facilitate the establishment of training programs that take into account the nycthemeral pattern of aminoacids deeply involved in the onset of central fatigue.

Daily rhythm of circulating fat soluble vitamin concentration (A, D, E and K) in the horse.

BACKGROUND: Many physiological processes of mammalian species exhibit daily rhythmicity. An intrinsic relationship exists between fat soluble vitamins (A, D, E and K) and several body functions. Few investigations on the rhythmic pattern of vitamins in domestic animals have been carried out. The present study evaluated the circadian rhythmicity of fat soluble vitamins in the horse. METHODS: Blood samples from 5 Thoroughbred mares were collected at four-hour intervals over a 48-hour period (starting at 8:00 hours on day 1 and finishing at 4:00 on day 2) via an intravenous cannula inserted into the jugular vein. Fat soluble vitamin concentration in the serum (A, D, E and K) was measured by HPLC. One-way repeated measures analysis of variance (ANOVA) was used to determine significant differences. p values < 0.05 were considered statistically significant. RESULTS: ANOVA showed a highly significant effect of time in all the horses for the vitamins studied (p < 0.0001). The application of the periodic model and the statistical analysis of the "Cosinor" enabled us to define the periodic parameters and their acrophases (expressed in hours) during the 2 days of monitoring: all the studied vitamins showed diurnal acrophases with values between 15:16 and 18:08 hours. CONCLUSION: Fat soluble vitamins exhibit daily rhythmicity with diurnal peak. Further investigations could help optimize the use of these substances according to their circadian (or other) rhythms.