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In patients with diabetes mellitus (DM), impairments of circadian rhythms, including the sleep–wake cycle, blood pressure, and plasma melatonin concentrations, are frequently observed. Animal models of DM are also reported to show aberrant circadian rhythms. However, the changes in the circadian rhythms of plasma soluble substances, including melatonin, in diabetic animals are controversial. In the present study, we investigated the circadian rhythms of spontaneous locomotor activity, metabolic parameters (plasma glucose, triglyceride, and total cholesterol), and plasma melatonin concentrations in Spontaneously Diabetic Torii (SDT) fatty rats, a novel animal model of type 2 DM. Although SDT fatty rats exhibited low locomotor activity in the dark phase, no phase shifts were observed. The circadian variations of plasma metabolic parameters were more apparent in the SDT fatty rats compared with control Sprague–Dawley (SD) rats. The circadian rhythms of plasma melatonin concentrations were significantly impaired in SDT fatty rats. To get an insight into the mechanism underlying the impaired melatonin secretion in SDT fatty rats, the expression of arylalkylamine N-acetyltransferase (Aanat) and acetylserotonin O-methyltransferase (Asmt) mRNA, which encode the rate-limiting enzymes for melatonin synthesis, was investigated in the pineal gland. There were no significant differences in Aanat and Asmt expression between the control SD and SDT fatty rats. These results suggest that SDT fatty rats show impaired circadian rhythms and dysregulated melatonin secretion.

In patients with diabetes mellitus (DM), impairments of circadian rhythms, including the sleep–wake cycle, blood pressure, and plasma melatonin concentrations, are frequently observed. Animal models of DM are also reported to show aberrant circadian rhythms. However, the changes in the circadian rhythms of plasma soluble substances, including melatonin, in diabetic animals are controversial. In the present study, we investigated the circadian rhythms of spontaneous locomotor activity, metabolic parameters (plasma glucose, triglyceride, and total cholesterol), and plasma melatonin concentrations in Spontaneously Diabetic Torii (SDT) fatty rats, a novel animal model of type 2 DM. Although SDT fatty rats exhibited low locomotor activity in the dark phase, no phase shifts were observed. The circadian variations of plasma metabolic parameters were more apparent in the SDT fatty rats compared with control Sprague–Dawley (SD) rats. The circadian rhythms of plasma melatonin concentrations were significantly impaired in SDT fatty rats. To get an insight into the mechanism underlying the impaired melatonin secretion in SDT fatty rats, the expression of arylalkylamine N-acetyltransferase (Aanat) and acetylserotonin O-methyltransferase (Asmt) mRNA, which encode the rate-limiting enzymes for melatonin synthesis, was investigated in the pineal gland. There were no significant differences in Aanat and Asmt expression between the control SD and SDT fatty rats. These results suggest that SDT fatty rats show impaired circadian rhythms and dysregulated melatonin secretion. [ABSTRACT FROM AUTHOR]

Summary: Depression is one of the most common psychiatric diseases and is commonly comorbid with type 1 or 2 diabetes mellitus (DM). However, the pathophysiology underlying the depressive state in DM remains poorly understood. Animal models are useful tools to investigate the association between depression and DM. In the present study we investigated whether the Spontaneously Diabetic Torii (SDT) fatty rat, a novel animal model of type 2 DM, shows depression‐related features. We assessed depression‐like behaviour, hyperactivation of the hypothalamic‐pituitary‐adrenal (HPA) axis, and neurotransmitter levels in the brain. Behaviour was evaluated using a forced swimming test, and the HPA axis was evaluated with changes in plasma corticosterone levels after a swimming stress exposure or dexamethasone challenge. In addition, serotonin (5‐hydroxytryptamine; 5‐HT), noradrenaline, glutamate and γ‐aminobutyric acid (GABA) concentrations in the frontal cortex, hippocampus and brain stem were measured. In the forced swimming test, SDT fatty rats exhibited increased duration of immobility compared with control Sprague–Dawley (SD) rats. Moreover, basal corticosterone levels were significantly elevated in SDT fatty compared with control SD rats. However, there were no stress‐induced increases or changes in dexamethasone‐induced suppression of corticosterone in SDT fatty compared with control SD rats. Furthermore, there were significant changes in 5‐HT concentrations in the prefrontal cortex, and in GABA and glutamate concentrations in the hippocampus in SDT fatty compared with controls. The results of the present study suggest that the SDT fatty rat may be an appropriate model for diabetes with comorbid depression associated with neurotransmitter impairments and aberrant basal HPA hyperactivity. [ABSTRACT FROM AUTHOR]

Thirty-one ICR pregnant mice were assigned to a control or a potassium chloride ( KCl) diet group to clarify the effects of KCl supplementation on water intake, bodyweight gains and serum components in pregnant and lactating mice, and 5% KCl was supplemented in KCl diets from 6.5 days post coitus to 1 or 14 days after parturition. Feed intake was not affected by treatment, but supplemental KCl decreased bodyweight gains of lactating mice and their neonatal mice. Water intake and urine volume of KCl supplemented mice were significantly higher than those of control mice during pregnancy and supplemental KCl decreased serum urea N in pregnant mice. Supplemental KCl increased water intake drastically in lactating mice immediately after parturition and increased serum K at 14 days after parturition. Histological alteration using hematoxylin-eosin was not found in the kidney of each mouse at 1 or 14 days after parturition. These results indicate that high KCl supplementation accelerates water intake in lactating mice and prevents bodyweight gains of maternal and neonatal mice during lactation. [ABSTRACT FROM AUTHOR]

Fifty-four mice were assigned to a control diet group or a KCl diet group to clarify the effects of KCl supplementation on growth rate, water intake and renal function in mice, and 5% of KCl was supplemented in KCl diets for 1–4 weeks. Bodyweights of KCl supplemented mice were significantly lower than those of control mice, and bodyweights of control and KCl supplemented mice at 28 days after treatment were 45.5 and 41.2 g, respectively. Feed intake was not affected by KCl supplementation, but water intake of KCl supplemented mice was significantly higher than that of control mice. Bone weights of KCl supplemented mice at 2 weeks after treatment were significantly lower than those of control mice. Serum urea nitrogen concentration at 4 weeks and serum K and Cl concentrations at 2 weeks were significantly lower in KCl supplemented mice. Histological alteration using hematoxylin–eosin and Sirius red staining was not found in the kidney of each mouse at 1, 2, and 4 weeks after treatment. These results suggest that high KCl supplementation decreases the rate of bodyweight gain and increases water intake in mice. [ABSTRACT FROM AUTHOR]

Thirty-four Holstein dry cows and 16 lactating cows were used in balance trials to identify the effects of feeding and animal performance on nitrogen (N), phosphorus (P) and potassium (K) excretion by dairy cows, and to develop prediction models for these excreta. Orchard grass silage, corn silage, alfalfa silage or timothy hay were offered to dry cows. Orchard grass silage or alfalfa silage, and concentrates were offered to lactating cows. In the statistical analysis, the independent variables were bodyweight (kg), dry matter (DM) intake (kg/day), milk yield (for lactating cows only, kg/day), water intake (free water plus water in feed, kg/day), intake (g/day) of N, P and K and dietary contents (% of DM) of crude protein, P and K. The dependent variables were N, P and K excretion (g/day) in feces and urine. In both dry and lactating cows, intake of N, P and K had large effects on corresponding excretion. The results indicated that a decrease in the intake of N, P and K could decrease the corresponding excretion. Further research by path analysis showed that K intake positively affected urinary N excretion in dry cows indirectly, through water intake and urine volume. [ABSTRACT FROM AUTHOR]

ABSTRACT Data from 65 cows were collected to clarify the relationship between parity and mineral status in Holstein cows during the periparturient period. Milk fever occurred in a second- and a fourth-lactation cow at parturition. Bodyweight of cows decreased immediately after parturition, and the decreased weights of cows from 1 to 6 days after parturition ranged from 11 to 27 kg. Milk yield of multiparous cows was higher than that of primiparous cows, but Ca and P concentrations in colostrum were not affected by the parity. Plasma glucose of primiparous cows was higher than that of multiparous cows, and plasma nonesterified fatty acids of fourth-and-more-lactation cows at parturition was highest. Plasma Ca concentration of cows at parturition decreased with advancing parity, and plasma inorganic P concentration of third-and-more-lactation cows was lowest at parturition. Plasma parathyroid hormone of fourth-and-more-lactation cows at parturition was highest, but plasma hydroxyproline and alkaline phosphatase was lowest. These results suggest that the large transfer of Ca and P to colostrum is a factor in the development of milk fever in third-and-more-lactation cows. [ABSTRACT FROM AUTHOR]