Search

Consumption of ergot alkaloids during the second half of gestation has been shown to decrease umbilical artery vasoactivity resulting in decreased birth weights. Negative vascular effects of ergot alkaloids are mediated predominantly through serotonergic and adrenergic receptors in other tissues. Vasoactivity of serotonin (5-HT) receptors 5-HT2A and 5-HT1B/1D in umbilical artery and vein from ewes receiving endophyte-infected seed (E + 1.77 mg ergovaline/hd/d) or a control total mixed ration (CON; 0 mg ergovaline/hd/d) tall fescue seed at d-110 and d-133 of gestation was evaluated. Gravid reproduction tracts were collected from ewes. Two-mm sections of umbilical artery and vein were exposed to increasing concentrations of a 5-HT1B/1D agonist and 5-HT2A agonist. The 5-HT1B/1D agonist did not stimulate a contractile response in artery or vein or either gestation time point. 5-HT2A agonist caused large responses in artery with greatest occurring at d-110 and decreasing in magnitude as days of gestation increased (p < 0.05). On d-110 and 133 of gestation, arteries from CON ewes had greater contractile response than arteries collected from E+ ewes (p < 0.05). Veins responded to increasing concentrations of the 5-HT2A agonist. Maximal d-110 vein response was greater than d-133 when exposed to 5-HT2A agonist (p < 0.05). Unlike the artery, veins from E+ ewes had greater d-133 contractile response than CON (p < 0.05). Vascular contractions of umbilical artery and vein are induced by 5-HT2A receptor activity and not 5-HT1B/1D. Umbilical artery 5-HT2A receptor activity was more sensitive to seed treatment and could be responsible for ergot alkaloid-induced intra-uterine growth restriction. [ABSTRACT FROM AUTHOR]

The predominant ergot alkaloid found in wild type endophyte-infected tall fescue grass is ergovaline. Ergovaline is a potent vasoconstrictor in livestock that consume it. Previous research has shown that ergovaline can bind serotonin (5-HT) receptors and blood vessels exposed to ergovaline become unresponsive to subsequent 5-HT exposure. Serotonin can stimulate vascular contraction or relaxation depending on the receptor subtype targeted. The objective of this experiment was to evaluate 5HT as vasorelaxant in the ovine saphenous artery and vein that were precontracted with ergovaline. Blood vessels were collected from mixed breed market rams (n = 7) at slaughter, cleaned of surrounding adipose and connective tissue, sliced into 2-mm cross-sections, and mounted in a multimyograph. Artery and vein cross-sections were equilibrated to 1 g tension in continuously gassed (95% O2/5% CO2) Krebs-Henseleit buffer (pH 7.4; 37.5 °C) for 90 min, precontracted with 1.0 μM ergovaline (in a tall fescue seed extract) for 30 min, exposed to increasing concentrations of 5-HT that ranged from 1 x 10-9 to 1 x 10-4 M for a 5-min interval. Response data were normalized to the 1.0 μM ergovaline response and were analyzed as a completely randomized design in SAS. The saphenous vein was larger in diameter blood vessel than the saphenous artery. Both vessel types contracted in response to exposure to 1 μM ergovaline. The saphenous artery had a much lower maximal response to ergovaline than did the vein (P < 0.05) that could be attributed to the size difference. The lateral saphenous vein relaxed to increasing concentrations of 5-HT (P < 0.05) with 87 % relaxation occurring by 1 x 10-6 M 5-HT. Conversely, the lateral saphenous artery contracted in response to increasing concentrations of 5-HT (P < 0.05) resulting in a 43% increase from the ergovaline response by the 1 x 10-4 M addition. This response did not become significant in the artery until 1 x 10-5 M 5-HT compared with 1 x 10-8 M for the vein. This resulted in a 50% effective concentration for 5-HT in the artery of 4.5 compared with 8.1 M for the vein (P < 0.05). The differing responses across vessels are likely a result of different receptor populations and this should be verified in future research. This is the first reported observation of stimulated relaxation of a blood vessel constricted ergovaline. Additional research is needed to understand the mechanism of how 5HT can be used to stimulate vasorelaxation in livestock suffering from ergot alkaloid-induced vasoconstriction. [ABSTRACT FROM AUTHOR]

Toxic tall fescue contains ergot alkaloids, which induce vasoconstriction in livestock, leading to fescue toxicosis. This condition can impact muscle development due to altered blood flow. Supplementation with 5-HTP may counteract the vasoconstrictive effects of fescue alkaloids. We aimed to investigate the influence of 5-HTP supplementation on satellite cells, myoblast, and preadipocyte numbers in maternal and fetal muscle during late gestation in Suffolk ewes. We hypothesized that 5-HTP supplementation would mitigate the effects of fescue toxicosis on muscle cell populations, potentially promoting muscle development and regeneration in maternal and fetal tissues. Suffolk ewes (n = 75), naïve to toxic tall fescue, were blocked by body condition score and body weight into 10 groups for synchronization. Ewes were confirmed pregnant using transabdominal ultrasound, and lamb number was estimated at gestational day (gd) 60. Pregnant ewes carrying twins (n = 30) were randomly assigned to one of three treatments: 1) negative control (CON, n = 10), 2) toxic tall fescue seed containing 1.77 mg ewe-1ּ d-1 ergovaline/ergovalinine plus 5-HTP (2.5 mg/kg BW) supplement (5HTP, n = 10), or 3) positive control, fed toxic tall fescue seed containing 1.77 mg ewe-1ּ d-1 ergovaline/ergovalinine (E+, n = 10). Ewes were individually fed a total mixed ration from gd 78 to gd 85 of pregnancy and then TMR plus treatment (CON, E+ or 5HTP) from gd 86 to d 111. On gd 112, terminal necropsies were performed, and semimembranosus muscle (SM) from the ewe and fetus was removed. Weights were obtained, and then samples were digested using pronase (1.5mg/mL) to isolate preadipocyte (PP1), myoblasts (PP2) and satellite cell (PP3) fractions using a pre-plating technique. Cells were quantified using a Neubauer-hemocytometer and trypan blue to also assess cell viability and changes in cell number. Fetal SM had a greater (P < 0.05) number of pre-adipocytes, myoblasts, and satellite cells per gram of tissue digested in comparison with the ewes. Pre-adipocyte and myoblast number per gram of tissue digested did not differ (P > 0.05) by treatment. The 5HTP group had the greater (P < 0.05) number of satellite cells per gram of tissue digested in comparison with the CON group. Satellite cell numbers tended (P < 0.10) to be greater in the 5HTP group in comparison to the E+ group. Satellite cell numbers from CON and E+ treatment groups did not differ (P > 0.05). In conclusion, 5-HTP supplementation during late gestation in Suffolk ewes exposed to toxic tall fescue significantly increased satellite cell numbers in maternal and fetal muscle tissues. This suggests a potential mitigation of the impact of fescue toxicosis on muscle cell populations. [ABSTRACT FROM AUTHOR]

microRNAs (miRNA) are small non-coding RNAs that modulate muscle satellite cell proliferation. Previous research identified miR-22-3p as differentially expressed during ovine muscle development and in vitro experiments showed that antagomir-22-3p treatment enhanced satellite cell proliferation. The objective of this study was to test in vivo vascular injection of antagomir-22-3p in lateral saphenous vein on miRNA and HDAC family mRNA expression in intrauterine growth restricted lambs. Pregnant ewes (n = 18) with twins were either fed at 100% of NRC (CON) or nutrient restricted (60% NRC; NR) from gestational d 85 to parturition. On d 12 of age, NR lambs (n = 8) were randomly selected and given a systemic injection of antagomir-22-3p in the lateral saphenous vein of the right leg (MIR-NR). CON lambs (n = 8) were also randomly selected and given a sham injection of PBS in the lateral saphenous vein of the right leg (SHAM-CON). Antagomir-22-3p was reconstituted in phosphate buffered saline (PBS). Injections were given for 3 consecutive days and lambs harvested 24 d later. Blood samples were collected from each lamb weekly to monitor miR22-3p expression. Lambs were slaughtered 24 d after the first injection and muscle mass measured. Muscle samples were removed for miR-22-3p and mRNA expression of potential targets. Cell-free circulating RNA was isolated from blood samples and miR-22-3p expression examined over time. Cell-free circulating miR22-3p expression was downregulated (P < 0.05) for MIR-NR compared with SHAM-CON on d 14 after injection. On d 21 after injection, miR-22-3p expression in plasma tended (P = 0.08) to be down-regulated in MIR-NR compared with SHAM-CON. Lamb body weight and muscle weights at harvest were similar between MIR-NR and SHAM-CON treatments. In heart and semimembranosus (SM) muscles, expression of miR-22-3p was down-regulated (P < 0.05) in MIR-NR compared with SHAM-CON. In the gastrocnemius and semitendinosus muscle, miR-22-3p expression was unchanged (P > 0.05). The number of type I and IIa muscle fibers were greater (P < 0.05) for MIR-NR than SHAM-CON. Muscle fiber area of Type I, IIa or IIx fibers did not differ (P > 0.05) by treatment. The number of type IIx fibers did not differ (P > 0.05) between treatments. MIR-NR treatment appears to shift muscle fibers towards more oxidative metabolism and down-regulate HDAC-1, 3, and 11 and SIRT6 in SM. The systemic injection of antagomir-22-3P downregulated miR-22-3p expression in circulation and in muscle tissues, which altered expression of HDAC/ SIRT genes involved in muscle fiber type conversion and hypertrophy [ABSTRACT FROM AUTHOR]

The deposition of fat in ruminants is a dynamic process that significantly impacts meat quality and production efficiency. The objective of this study was to investigate the dynamics of fat deposition over time across various depots in bottle-fed ram lambs, focusing on pre-adipocyte cell number and gene expression as a key determinants of fat accumulation. Suffolk ram lambs (n = 13) were serially harvested on d 15 (n = 4), d 45 (n = 4), and d 105 of age (n = 5). Lambs were supplemented with milk replacer 20% of body weight (BW)] from d 5 to d 30 of age, milk replacer (10% BW) with creep feed (2.5% of BW) supplementation from d 30 to 45, and creep feed (5% of BW) from d 45 to d 105 of age. At each harvest timepoint, fat depots, including subcutaneous, intramuscular (longissimus muscle), and visceral fat, were snap-frozen for RNA extraction, downstream gene expression analysis, and fatty acid extraction. Pre-adipocyte cells were also preserved, enzymatically digested and subsequently isolated from each depot. Pre-adipocyte cell number was assessed using the CellDrop (Denovix). Preliminary results revealed that pre-adipocyte cell numbers were significantly greater (P < 0.05) in subcutaneous and visceral depots 17-d old lambs in comparison to all other depots in other timepoints. The number of pre-adipocytes in intramuscular adipose depots did not differ over time (P > 0.05). Visceral and subcutaneous adipose depots had a significantly greater (P < 0.05) amount of preadipocytes present in comparison with the intramuscular depot. Total fatty acid content differed (P < 0.05) among depots and timepoints. Omental fat from d 105 lambs exhibited the greatest (P < 0.05) total fatty acid content in comparison with all other depots. Total fatty acid amount did not statistically differ (P > 0.05) between d 17 and d 45 omental fat depots. Total fatty acid content did not differ (P > 0.05) over time in intramuscular fat samples (LM). The gene expression of several proposed pre-adipogenic markers were evaluated across timepoints and tissues. Moreover, the relationship between pre-adipocyte cell number and fat deposition in both subcutaneous and visceral depots indicates their crucial role in overall fat accumulation in ram lambs. These findings offer novel insights into the dynamics of fat deposition in ruminants, emphasizing the importance of intramuscular fat depots as key sites for fat accumulation. Understanding the relationship between pre-adipocyte cell number and fat deposition across depots can inform management strategies aimed at enhancing meat quality and production efficiency in sheep farming systems. Further research is needed to elucidate the molecular mechanisms underlying fat deposition in different depots and its impact on meat quality traits. [ABSTRACT FROM AUTHOR]

Farmed rainbow trout require specific cold, freshwater habitations to maximize overall growth for future release and general production. The growth and development of muscle tissue in rainbow trout are critical factors in understanding and maximizing the production and quality of farmed fish. Unlike mammals, rainbow trout can undergo muscle hyperplasia and hypertrophy throughout its lifetime, which only adds to its muscle growth potential as a species. This study aimed to investigate the growth patterns and gene expression changes in red, pink, and white muscle tissue over time in farmed rainbow trout. Twenty rainbow trout were harvested at 6 and 7 mo of age from the Walhalla State Hatchery (SC), and red, pink, and white muscle samples were collected in RNAlater for RNA extraction and downstream gene expression analysis. General growth pattern changes were assessed through measurements of wet body weight, wet length, empty carcass weight, and filet weight, while gene expression changes were examined using quantitative polymerase chain reaction (RT-qPCR). Genes such as PAX7A, PAX7B, MYOG, MYOD, IGF1, and IGF2B were investigated to illuminate dynamic changes in the muscle tissue of rainbow trout. These genes are associated with myogenic regulatory factors involved in muscle growth and development. Water and ambient temperature were captured to monitor potential temperature effects. Wet weight (g) and left filet weight (g) increased (P < 0.05) over the 30-d period. PAX7A, PAX7B, and MYOG were all downregulated (P < 0.05) in red and pink muscle in comparison to the previous 30 d. White muscle displayed no differences (P > 0.05) in expression of PAX7A, PAX7B, and MYOG. IGF1 gene expression in red, pink and white muscle were downregulated (P < 0.05) over the 30 d. MYOD had a very low expression in comparison with other target genes during these age points. These findings highlight the dynamic nature of muscle growth in rainbow trout and the importance of red and pink muscle dynamics. Understanding the molecular mechanisms underlying muscle growth and gene expression changes over time can inform strategies to optimize fish growth and meat quality in aquaculture systems. Further investigation is needed to elucidate the specific regulatory pathways involved in muscle development and their potential applications in fish farming. [ABSTRACT FROM AUTHOR]

Herbivores that consume ergot alkaloids frequently suffer from vasoconstriction that can result in a myriad of symptoms that can range from necrosis of peripheral tissues to fetal intra-uterine growth restriction. As part of a larger study screening compounds that may mitigate the vasoconstrictive effects of ergot alkaloids, the objective of this experiment was to evaluate serotonin (5-HT) as vasorelaxant in the ovine saphenous artery and vein. Blood vessels were collected from a total mixed breed market rams (n = 16; approximate BW = 58 kg) at slaughter, cleaned of surrounding adipose and connective tissue, sliced into 2-mm crosssections, and mounted in a multimyograph. Artery and vein cross-sections were equilibrated to 1 g tension in continuously gassed (95% O2/5% CO2) Krebs-Henseleit buffer (pH 7.4; 37.5 °C) for 90 min, precontracted with 0.0001 M phenylephrine for 15 min, exposed to concentrations of 5-HT that ranged from 1 x 10-9 to 1 x 10-4 M for a 5-min interval. Response data were normalized to the 0.0001 M phenylephrine response and were analyzed as a completely randomized design in SAS. The lateral saphenous vein (n = 5 lambs) relaxed to increasing concentrations of 5-HT (P < 0.05) with 65 to 75 % relaxation occurring at 1 x 10-7 M through 1 x 10-4 5-HT. Conversely, the lateral saphenous artery (n = 6 lambs) contracted in response to increasing concentrations of 5-HT (P < 0.05) resulting in a 255% increase from the phenylephrine response by the 1 x 10-4 M addition. In a subsequent experiment, saphenous veins from the remaining lambs (n = 5) were treated the same, but in place of increasing concentrations of 5-HT, saphenous veins were exposed to increasing concentrations of selective 5-HT receptor agonists to determine the receptor subtypes involved in the previously observed vasorelaxation. Agonists for receptors 5-HT2B (BW 723C86; a-methyl-5-(2-thienylmethoxy)-1H-indole-3-ethanamine hydrochloride), 5-HT4 (BIMU-8; 2,3-Dihydro-N-[(3-endo)-8-methyl-8-azabicyclo[3.2.1]oct-3-yl]-3-(1-methylethyl)-2-oxo-1Hbenzimidazole-1-carboxamide hydrochloride), and 5-HT7 (LP44; 4-[2-(methylthio)phenyl]-N-(1,2,3,4-tetrahydro-1-naphthalenyl)-1-piperazinehexanamide, monohydrochloride) were used. These 5-HT receptor subtypes were selected based on their association with vascular smooth muscle relaxation. While all three 5-HT receptor subtypes resulted in vasorelaxation (P < 0.05), the 5-HT2B agonist only stimulated a maximal relaxation of 32% compared with the agonists for 5-HT4 and 5-HT7 that resulted in maximal relaxation of 68% and 50%, respectively. The agonist for 5-HT4 produced the greatest relaxation in the ovine lateral saphenous vein and should be targeted in subsequent research. It is likely that the combined effect of binding multiple receptor subtypes contributes to the overall effect of 5-HT. The focus on development of ergot alkaloid mitigation strategies should consider the divergent responses of arteries and veins to serotonin in peripheral tissues. [ABSTRACT FROM AUTHOR]