Insulin resistance in early lactation includes low glucose concentration, low insulin release and responsiveness and high lipolysis. Niacin is important antilipolytic agent and leads to increase glucose and insulin concentration. The objectives of this study were to determine the influence of niacin on the insulin resistance in cows during early lactation using the difference of value and regression analysis between blood non-esterified fatty acid (NEFA), glucose and insulin concentrations, revised quantitative insulin sensitivity check index and glucose-to-insulin ratio. Niacin supplementation led to a decrease of NEFA concentration and an increase of glucose and insulin concentrations during the first three weeks after calving. Cows in the niacin group which were more resistant to insulin showed higher concentrations of non-esterified fatty acid in comparison with more sensitive cows from the same group, but still lower than the control. The regression analyses suggest the following characteristics of cows supplemented with niacin in comparison with the control group: the insulin response to glucose was more intense; the antilipolytic effect of insulin was lower; insulin efficiency expressed as glucose-to-insulin ratio increase with a decrease in NEFA. The metabolic changes due to niacin supplementation showed a dual influence on the insulin resistance in dairy cows during early lactation: decreased NEFA concentrations led to a decrease in the insulin resistance (due to an increase in insulin efficiency and insulin sensitivity index), but increased concentrations of insulin and glucose possibly caused an increase in the insulin resistance in dairy cows (due to lower insulin sensitivity index and possibly lower antilipolytic effects of insulin).

HighlightsWe studied the development of tolerance to subchronic p.o. administration of DZN in rats, under both in vivo and in vitro conditionsAs a consequence of AChE inhibition, ACh neurotransmitters are being accumulated in over stimulated nicotinic and muscarinic receptors.With isolated diaphragm and ileum, we examined the down regulation of nicotinic and muscarinic receptor function through EFS technique.The results of our research could be useful in forensic diagnostics of organophosphate poisoning.

The effects of physostigmine, L-arginine and NG-nitro-L-arginine methyl ester (L-NAME) were investigated in urethane-anaesthetized rats. The drugs were chosen because physostigmine has been known to produce an increase in peripheral adrenergic activity, whereas L-arginine and L-NAME have been known to modulate nitric oxide (NO) production. Slow infusion of L-arginine produced significant hypotension, but only in animals pretreated by physostigmine. L-NAME applied in the same way produced a slow developing increase in blood pressure, but not in animals pretreated by physostigmine. The pressor responses to physostigmine were potentiated if the drug was injected during infusion of L-NAME, and depressed if the drug was injected after stopping L-NAME infusion (in rats not pretreated with physostigmine). It is concluded that L-arginine-NO pathways act in vivo to oppose peripheral vasoconstrictor influences coupled with central cholinergically mediated activation of the adrenergic system, as produced by physostigmine. In this way, NO is part of a general mechanism for blood pressure regulation.

Citation of This Article AbstractThe objective of this study was to evaluate the effect of niacin on the metabolic parameters and lipolysis inhibition in dairy cows during early lactation. A total of 30 clinically healthy, multiparous Holstein-Friesian cows in late gestation were enrolled in the study (15 supplemented with niacin (120 g/d/ cow) and 15 in the negative control group). Blood samples were taken weekly for 3 weeks after calving. The research results show that cows that received niacin indicated lower NEFA concentrations in all three weeks of the experiment. The NEFA concentrations did not change from weeks 0 to 2 after calving in the niacin group, whereas the NEFA concentrations in the control group were significantly increased (P<0.05). The administration of niacin exerted significant effects on the metabolic adaptations in cows during early lactation. Niacin significantly decreased BHB, MDA, total bilirubin, urea and phosphorus concentrations and liver enzyme activity (AST, ALP and GGT) and increased albumin, cholesterol, triglyceride and glucose concentrations. The administration of niacin significantly affected the correlation and regression between NEFA concentrations and other metabolic parameters, rendering the glucose, cholesterol, triglycerides, total bilirubin, AST, albumin, urea and phosphorus values less regressed against the NEFA values. In conclusion, niacin administration decreases lipolysis and metabolic adaptations proved to be less dependent on NEFA concentrations in niacin group compared to the control group. Keywords: Cow, Niacin, Lipolysis, Metabolic profile Erken Laktasyon Süresince Sütçü İneklerde Niasin İlavesinin Metabolik Parametreler ve Lipoliz Üzerine Etkisi ÖzetBu çalışmanın amacı erken laktasyon süresince sütçü ineklerde niasinin metabolic parametreler ve lipolizi inhibe etme üzerine etkilerini araştırmaktır. Toplam 30 adet klinik olarak sağlıklı geç gebelik dönemindeki multiparous Holstein-Friesian inek (15'i 120 g/gün niasin takviyesi verilmiş ve 15'i negatif kontrol) çalışmada kullanıldı. Kan örnekleri doğumu takiben 3 hafta süresince haftalık olarak alındı. Çalışma sonuçları niasin alan ineklerde 3 hafta süresince NEFA konsantrasyonunun daha düşük olduğunu gösterdi. NEFA konsantrasyonu 0 ile doğumdan sonraki 2 hafta boyunca niasin grubunda değişmezken kontrol grubunda anlamlı oranda artma gösterdi (P<0.05). Niasin verilmesi erken laktasyon dönemindeki ineklerdeki metabolik adaptasyona anlamlı derecede etki etti. Niasin anlamlı oranda BHB, MDA, total bilirubin, üre ve fosfor konsantrasyonları ile karaciğer enzim aktivitesini (AST, ALP ve GGT) düşürürken albümin, kolesterol, trigliserid ve glikoz konsantrasyonlarını artırdı. Niasin verilmesi anlamlı oranlarda olmak üzere NEFA konsantrasyonları ile diğer metabolik parametreler arasındaki korelasyon ve regresyonu etkiledi. Glikoz, kolesterol, trigliserid, total bilirubin, AST, albümin, üre ve fosfor değerleri NEFA değerlerine göre daha az gerileme gösterdi. Sonuç olarak, niasin verilmesi lipolizi azaltırken metabolik ada...

The pharmacokinetics of diclofenac was studied in 10 clinically normal male Yorkshire pigs, following intramuscular (i.m) administration of a single dose of diclofenac-sodium (2.5 mg/kg body weight). Diclofenac serum concentrations were determined by high pressure- liquid-chromatography (HPLC), with UV detection (226 nm). Following i.m. administration all individual diclofenac serum levels best fitted the one-compartment open model for extravascular administration. The maximal diclofenac serum concentration of 5.88 ± 0.934 mg/L was reached after 0.80 ± 0.35 h. The absorption half-life was 0.36 ± 0.25 h, and the area under the concentration vs. time curve (AUC0→∞) was 20.32 ± 4.521 mgh/L. A monoexponential concentration decline and small volume of distribution (Vd) of 0.29 ± 0.100 L/kg indicated a rapid, but not extensive distribution of diclofenac between central and peripheral compartment(s). Total clearance was 0.13 ± 0.034 L/h/kg, and elimination half-life was short (1.67 ± 0.743 h), as a result of a rapid distribution and extensive metabolism of diclofenac in the pig's body. When administered i.m. to pigs, diclofenac is absorbed and distributed rapidly. Distribution is not extensive, suggesting that diclofenac is predominantly retained in the central compartment. The elimination of the drug from the pig's circulation is also rapid, most of it probably being a result of extensive metabolism in the liver