Gurkan Cikim

Daily rhythm of glutathione peroxidase activity, lipid peroxidation and glutathione levels in tissues of pinealectomized rats

Melatonin is a component of the antioxidant defense system since it has radical scavenging and antioxidant activities. In the present study, we aimed to investigate the endogenous rhythm of antioxidant enzyme glutathione peroxidase (GSH-Px) activity, oxidized glutathione (GSSG) and lipid peroxidation levels in tissues of pinealectomized rats (PINX). Rats were sacrificed by decapitation at 4 h intervals. GSH-Px activity, GSSG and lipid peroxidation levels showed a daily rhythm both in controls and in PINX rats. GSH-Px and GSSG exhibited the peak levels after the peak time of melatonin which was determined previously by other groups. Lipid peroxidation levels increased progressively during the night and started to decline before the GSH-Px peak time. These findings suggest that endogenous melatonin is involved in the night time increase of GSH-Px activity and GSSG levels and modulates the daily rhythm pattern of GSH-Px. In conclusion, pinealectomy which eliminates the melatonin rhythm has a supressor effect on GSH-Px activity levels.

Levels of cytokines (IL-1beta, IL-2, IL-6, IL-8, TNF-alpha) and trace elements (Zn, Cu) in breast milk from mothers of preterm and term infants.

It has been well documented that human milk contains several immunomodulator components which are important during infant period when the newborns immune system is still under development. In this study, we aim at examining levels of cytokines, zinc (Zn), and copper (Cu) in milk from mothers of premature and mature infants, and comparing changes during lactation periods consequently. Milk was collected from total of 40 mothers (group M: mothers of mature infants, n = 20; group PM: mothers of premature infants, n = 20) from four lactation stages: colostrum (0–7 days), transitional (7–14 days), mature milk (21 days), and mature milk (2nd month). Levels of cytokines (interleukin [IL]-lβ, IL-2, IL-6, IL-8, tumor necrosis factor-alpha [TNF-α]) were determined by chemiluminesence method, whereas atomic absorption spectrophotometer was used for the determination of Zn and Cu levels. Cytokine levels were determined to be high in colostrum and transient milk from mothers of full-term infants, whereas their levels were reduced drastically in the 21st day and the 2nd month milk (P < .01 , P < .001). Similar trends were observed in milk from mothers of premature infants, but cytokine levels were significantly lower in colostrum compared to colostrum from mothers of mature infants (P < .01). The differences in cytokine levels were continuous in transient milk (P < .05) and mature milk (21 days) (P < .05), whereas there was no statistically significant differences between milk from both groups of mothers in the 2nd month (P > .05). Zn levels in milk from mothers of premature infants were significantly lower compared to the ones from mothers of mature infants (P < .01) and these differences continued through the 2nd month. Although Cu levels were lower in milk from mothers of premature infants, there was no statistically significant difference except colostrum (P > .05). Our results clearly demonstrate that the level of immunomodulating agents such as cytokines and trace elements in milk from mothers of premature infants is less than the level of the same agents in milk from mothers of full-term infants. Although there are commercially available products for infant feeding, human milk is still the best natural nutrient for newborns. Therefore, when premature infants are breastfed, necessary precautions such as supplemantary diets must be considered for possible infections and risks related with immune system deficiency.

Chromium picolinate, rather than biotin, alleviates performance and metabolic parameters in heat-stressed quail

1. The effects of chromium picolinate and biotin supplementation alone and in combination on performance, carcase characteristics, malondialdehyde (MDA), vitamin C, vitamin E, glucose and cholesterol levels were evaluated in Japanese quail exposed to high ambient temperature. 2. Two hundred and forty quails (10 d old) were assigned randomly to 4 dietary treatments at room temperature (22°C; thermoneutral, TN) or ambient (34°C for 8 h/d; heat stress, HS). Both TN and HS were fed either on a basal (control) diet or the basal diet supplemented with 400 µg of Cr/kg (Cr group), 0·5 mg of biotin/kg of diet (biotin group) or both (Cr + Biotin group). 3. Supplementing the diet of heat-stressed quails with chromium picolinate improved live weight gain, feed intake, feed efficiency and carcase traits. Biotin supplementation during TN and HS conditions did not have any beneficial effects on body weight gain, feed intake, feed efficiency or carcase traits. 4. Either in combination or alone, chromium picolinate increased serum concentrations of vitamins C and E, but decreased MDA, glucose and cholesterol concentrations in birds kept at high ambient temperature. There was no difference in vitamins C and E and MDA concentrations between birds given chromium picolinate and birds receiving chromium picolinate plus biotin, while glucose and cholesterol levels were significantly lower in all groups. The lowest concentrations of cholesterol and glucose were found in the combination group under both TN and HS conditions. An interaction between diet and temperature was detected for glucose and cholesterol concentrations. 5. Excretion rates for zinc, iron and chromium were lower in TN groups than in the corresponding HS groups. Supplementing diet with chromium picolinate and chromium picolinate plus biotin decreased excretion of minerals while biotin alone did not effect excretion of minerals. 6. Chromium supplementation, but not biotin supplementation, attenuated the decline in performance and antioxidant status resulting from heat stress.

Insulin increases homocysteine levels in a dose-dependent manner in diabetic rats.

BACKGROUND Even moderate increases in levels of homocysteine cause cardiovascular degeneration. Various genetic and nutritional factors affect plasma homocysteine concentrations, and hyperhomocysteinemia damages vascular endothelial cells; hence their functions are disrupted. In diabetes mellitus, homocysteine metabolism is altered and as a result, more severe diabetic complications are expected when hyperhomocysteinemia occurs. METHODS In the present study we experimentally induced diabetes in rats and examined effects of low or high dose of insulin administration on homocysteine metabolism. RESULTS We determined that homocysteine levels were reduced in STZ-induced diabetic rats. This reduction was normalized by insulin in a dose-dependent manner. On the other hand, increased levels of lipid parameters (cholesterol, triglycerides, HDL) were reduced by insulin. CONCLUSIONS Hcy level in experimentally induced insulin-dependent diabetes mellitus is decreased and injection of insulin normalizes Hcy levels in a dose-dependent manner. We speculate that insulin increases activities of enzymes of transsulfuration and remethylation reactions and hence speeds up conversion of Hcy to methionine and cysteine.

Epigallocatechin-3-gallate supplementation can improve antioxidant status in stressed quail

1. Heat stress causes oxidative stress, which decreases plasma antioxidants in poultry. Epigallocatechin gallate (EGCG), the most abundant polyphenol in green tea, is a powerful antioxidant against lipid peroxidation. This experiment was conducted to evaluate the effects of dietary EGCG supplementation on performance, carcase characteristics, concentrations of malondialdehyde, lipid peroxidation indicator, vitamins C, E, A, cholesterol, triglyceride, and glucose in Japanese quail (Coturnix coturnix japonica) exposed to a high ambient temperature of 34°C. 2. One hundred and eighty Japanese quails (10 d old) were assigned at random to 6 treatment groups consisting of 10 replicates of three birds. Birds were kept in cages in a temperature-controlled room at either 22°C (thermo-neutral) or 34°C (heat stress) for 8 h/d. Birds were fed either a basal diet or the diet supplemented with 200 or 400 mg of EGCG/kg of diet. 3. EGCG supplementation linearly increased feed intake, live weight gain, feed efficiency, cold carcase weight and yield under heat stress conditions but did not show the same effect at thermoneutral conditions. Serum vitamin C, E, and A concentrations increased in birds reared at high temperature while non-significant changes occurred in thermo-neutral groups. Malondialdehyde concentrations in serum and liver decreased in all birds of both thermo-neutral and heat stressed groups as dietary EGCG supplementation increased. Heat stress-induced increase in serum cholesterol, triglycerides and glucose concentrations were linearly reversed by EGCG supplementation. 4. The results indicate that EGCG supplementation improved the live performance and antioxidant status of heat-stressed Japanese quail.

Relationship among levels of leptin and zinc, copper, and zinc/copper ratio in plasma of patients with essential hypertension and healthy normotensive subjects

Obesity is among the main contributing factors in the etiology of essential hypertension (EHT). Leptin, the product of the ob gene, is expressed mainly in adipose tissue. We examined the relationship between two trace elements, zinc (Zn) and copper (Cu), and leptin in patients with EHT (n=35) and normotensive (NT) controls (n=50) because leptin as well as Zn and Cu were reported to be associated with the pathophysiology of EHT. Plasma leptin levels were determined with a commercial enzyme-linked immunosorbent assay (ELISA) kit. Atomic absorption spectrophotometry was utilized to determine plasma Zn and Cu levels. There was a negative correlation between leptin and Zn, and the Zn/Cu ratio (r=−0.359, p<0.05; r=0.361, p<0.05, respectively) in pooled subjects. When subjects were divided based on the presence or absence of hypertension, there was a negative correlation between leptin and Zn (r=−0.375, p<0.05) as well as leptin and Zn/Cu ratio (r=−0.398, p<0.05) in NT subjects. Similar trends were observed when leptin/BMI (body mass index) levels were utilized. There was no significant correlations between levels of Cu and leptin or leptin/BMI. In conclusion, in addition to high leptin levels, Zn and the Zn/Cu ratio were lower in patients with EHT compared to NT controls.

The effect of soy isoflavones on egg quality and bone mineralisation during the late laying period of quail

1. Soy isoflavones play a role in calcium and bone metabolism. Poor egg quality, skeletal abnormalities and architectural deterioration of bone tissue are common problems under hot climate conditions and with increased age in poultry. 2. In this study, we investigated the effects of soy isoflavone supplementation on egg production, egg quality, bone mineral density (BMD), levels of osteocalcin (OC), vitamin D, calcium (Ca), phosphorus (P) and alkaline phosphatase (ALP) activity in quail (Coturnix coturnix japonica) during the late laying period. 3. The birds (n = 180; 28 weeks old) were randomly assigned to 6 treatment groups consisting of 6 replicates of 5 birds each in a 2 × 3 factorial arrangement of treatments (temperatures, soy isoflavone concentration). Birds were kept in wire cages in a temperature-controlled room at either 22°C (thermo-neutral, TN) or 34°C (heat stress, HS) for 8 h/d (09:00 to 17:00 h; until the end of the study) and fed either on a basal (control) diet or on the basal diet supplemented with either 400 or 800 mg of soy isoflavones/kg of diet. 4. Heat exposure reduced feed intake, egg production, egg quality, BMD, OC, vitamin D, Ca, P and ALP when the basal diet was given. Feed intake, egg production and egg weight were not affected, while eggshell thickness and eggshell weight increased in soy isoflavone-supplemented quails reared under TN conditions. However, feed intake, egg production, egg weight, eggshell thickness, eggshell weight and Haugh units were positively influenced by soy isoflavone supplementation in HS groups for quail during the late laying period. Bone mineral density, serum OC, vitamin D, Ca, P levels and ALP activity were significantly improved by soy isoflavone supplementation in both the TN and HS groups in quail during the late laying period. 5. Soy isoflavone supplementation of basal diet significantly improved egg quality and bone mineralisation in quail during the late laying period.

Effects of dietary combination of chromium and biotin on growth performance, carcass characteristics, and oxidative stress markers in heat-distressed Japanese quail.

Environmental stress causes adverse effects in performance and antioxidant status of poultry. Dietary chromium supplementation promotes the growth rate and feed efficiency of growing poultry and these beneficial effects of chromium appear to be greater under stress. Biotin, a member of the vitamin B complex, is involved in the metabolism of carbohydrates, fats, and proteins. In a previous experiment, we examined the effects of chromium picolinate (CrPic) as a chromium source in birds subjected to high environmental temperature and the data showed that supplementation with CrPic ameliorated the deletorious effect of stress. The study was conducted to determine the effects of a supplementation of combination of CrPic and biotin (DiachromeTM) on performance, carcass characteristics, levels of oxidative stress markers, serum cholesterol, and glucose concentrations in Japanese quail (Coturnix coturnix japonica) exposed to high ambient temperature of 34°C. Two hundred forty Japanese quail (10 d old) were randomly assigned to 8 treatment groups consisting of 10 replicates of 3 birds. The birds were kept in a temperature-controlled room at 22°C (thermo-neutral [TN] groups) or 34°C (for 8h/d; 09.00 am to 05.00 pm; heat-stress [HS] groups). Birds were fed either a basal (control) diet (TN and HS) or the basal diet supplemented with either 1, 2 or 4 mg of Diachrome/kg of diet. Heat exposure decreased performance when the basal diet was fed (p=0.001). Diachrome supplementation increased feed intake (p=0.001), body weight (p=0.05), feed efficiency (p=0.01), and carcass traits (p≤0.05) variables linearly in birds reared under HS conditions. Serum vitamin C (p=0.05) and vitamin E (p=0.03) concentrations increased, whereas malondialdehyde (MDA) levels in serum and the liver (p=0.01), thigh muscle (p=0.05), and serum cholesterol and glucose concentrations (p=0.05) decreased in supplemented birds reared at a high temperature. It should be noted that when birds were kept at the thermo-neutral temperature, Diachrome supplementation did not affect (p>0.05) the variables measured, with the exception of a reduction in serum cholesterol and glucose. Results of the present study suggest that Diachrome can be considered a protective dietary supplement by reducing the negative effects of high environment temperature on performance and oxidative stress in quail.

Effects of pinealectomy on the levels and the circadian rhythm of plasma homocysteine in rats

Abstract: Hyperhomocysteinemia is an independent cardiovascular risk factor. There are several factors including aging that contribute to the development of hyperhomocysteinemia. Nevertheless, the exact mechanisms causing this condition are still debated. We hypothesize that the age‐related decrease in melatonin levels may be consequential in hyperhomocysteinemia. Recently, we found that plasma homocysteine (Hcy) levels are increased in pinealectomized (PINX) rats and melatonin reverses this increase. The aim of the present study was to determine if there is a circadian rhythm of plasma Hcy in rats and to examine the effect of pinealectomy on this cycle. Plasma Hcy levels demonstrated a 24‐hr rhythm with a peak at 02:00 hr and a nadir at 14:00 hr in both control and PINX rats. Pinealectomy did not change the phase of the rhythm or the nocturnal elevation of plasma Hcy, but it did significantly increase mean plasma Hcy levels compared with those in controls and in rats that were sham pinealectomized (sPINX) (P < 0.05). Melatonin decreases plasma Hcy levels while causing an increase in total glutathione (tGSH). In conclusion, we speculate that decreasing levels of melatonin during aging lead to hyperhomocysteinemia and a decrease in tGSH and the latter may be one of the factors causing hyperhomocysteinemia in the elderly population.