Effects of caffeine on the bones of aged, ovariectomized rats

Caffeine is a substance which many people consume in their daily life. Caffeine's effects on bone are still controversial. Using ovariectomized rats, the present study was conducted to determine to what extent caffeine intake affects the mechanical properties, bone minerals and histology. Aged rats were divided into 2 groups after ovariectomy. Group 1 was fed a 20% protein diet as a control, and group 2 was fed a 20% protein diet supplemented with caffeine (2 mg/100 g body weight). The respective diets were fed to the rats of each group for 90 days. Rats were then killed by heart puncture, blood was collected, and femurs were removed. In 1 group of femurs paraffin cross-sections were made at the midshaft of each bone. Total width, cortical width, total cross-sectional bone area of the midshaft, and the number of osteocytes in randomly selected areas were measured. Another group of bones was subjected to three-point bending testing until failure. Bones were then pulverized and Ca, P, Mg, Zn, Sr, Si, hydroxyproline and hexosamine contents and crystallite size were measured. Various mechanical properties, except modulus of elasticity, in the caffeine group were consistently 7-23% lower than the noncaffeine controls. Yield strain in the caffeine group was significantly less than in the noncaffeine controls. Zinc, Sr, and crystallite size of bone showed a significant decrease in the caffeine group, whereas Si contents significantly increased. Our current results indicate that routine intake of caffeine in the elderly should be regarded with some caution.

Combined effects of caffeine and prostaglandin E2 on the proliferation of osteoblast-like cells (UMR106-01)

BACKGROUND

The general public widely consumes caffeine (1,3,7-trimethylxanthine), which is contained in various foods, beverages and over-the-counter medications. We have shown previously that caffeine intake could affect bone metabolism in vivo.

METHODS

Because prostaglandin E2 (PGE2) is shown to be elevated in the periodontally diseased site, the possible interaction between caffeine and PGE2 was investigated in the present study using UMR106-01 rat osteoblast-like cells in vitro.

RESULTS

Although neither 0.1 mM caffeine nor 0.1 microg/ml of PGE2 alone showed any inhibitory effects on cell proliferation, the combination of caffeine and PGE2 showed significant inhibition. However, in order to have inhibitory effects, both caffeine and PGE2 had to be present at least 72 or 96 hours in the medium. Addition of the endogenous PGE2 synthesis inhibitor, indomethacin, showed no effects on cell proliferation. Neither cAMP-inducing agent IBMX (0.01 mM and 0.1 mM) nor forskolin (0.001 mM) inhibited cell proliferation, but combined with PGE2 these agents strongly inhibited proliferation as was observed with the combination of caffeine and PGE2, suggesting possibly that the increase of intracellular cAMP concentration plays an important role in the inhibitory effects of cell proliferation.

CONCLUSIONS

The present data for the first time demonstrate the possible implication of routine caffeine intake in the acceleration of pathological conditions of periodontitis. Thus, we propose that chronic caffeine intake is one of the possible risk factors in the advancement of pathology in the periodontitis patient. Further research in this area is warranted.

Combined effects of caffeine and alcohol during pregnancy on bones in newborn rats

The combined effects of caffeine and alcohol on mineral contents of fetal mandibles and femurs were studied. Pregnant rats were divided into four groups: group 1, control; group 2, caffeine; group 3, alcohol; and group 4, caffeine-plus-alcohol. Alcohol (1.0 g ethanol/kg body weight) was intubated twice daily, beginning at day 9 of gestation. Caffeine (2 mg/100 g body weight) was given as a dietary supplement. Groups 1 and 2 were intubated with isocaloric sucrose solution. At birth, randomly selected pups were killed and the mandible and femur were removed and dried. Ca, P, Mg, Zn and hydroxyproline in these bones were measured. Notwithstanding the dams' intake of caffeine and alcohol administered separately, the present results suggest that the combination of caffeine and alcohol exhibited the most detrimental effects.

Effects of caffeine on the DNA and protein synthesis of the protein-energy malnourished neonatal cardiac muscle cells in culture

1. The growth of cardiac cells derived from newborn rats whose dams were either malnourished or malnourished with caffeine during pregnancy was inhibited in culture over the period of 5 days as compared to that of the normally nourished cells. 2. Cells derived from malnourished rats with caffeine added to their diets showed a greater inhibition than those from the malnourished rats not given caffeine. 3. Both DNA and protein synthesis showed an inhibition due to caffeine in a dose-dependent manner using normally nourished cells. 4. In the presence of exogenous 2 mM caffeine, the degree of percent inhibition of DNA and protein synthesis of cells derived from rats malnourished with caffeine was less than that from the rats with malnutrition alone. 5. The present data indicated that malnutrition combined with caffeine during pregnancy exerted a greater negative effect on the nature of cell growth than malnutrition alone and these cells became less sensitive to exogenous caffeine.

Intestinal absorption of linoleic acid in experimental renal failure

Linoleic acid (LA) transport in rats with experimental short-term and long-term renal failure (RF) was compared with that of sham-operated normal animals on liberal food intake and pair-fed animals. The perfusions in vivo and incubations in vitro were conducted using a micellar solution containing a wide range of LA concentrations. Both absorption in vivo and uptake in vitro of LA were significantly reduced in animals with short-term RF. Lipid extraction and separation by thin-layer chromatography revealed a marked LA trapping as trilinolein (TL) in the perfused intestinal tissue in the short-term RF group. The esterification process, as defined by the rate of LA incorporation into TL, was moderately reduced in short-term RF animals. The thickness of the unstirred water layer showed no significant difference among the groups studied. In contrast, animals with long-term RF exhibited normal absorption of LA in vivo at all concentrations tested. In conclusion, LA absorption is reduced in short-term RF and restored in long-term RF. Several steps including LA transport into and TL transport out of the enterocyte and the esterification process were impaired in short-term RF. These changes are not due to alteration in the unstirred water layer, anorexia, weight loss or a rapid effect of uraemic chemical environment or circulatory factors.

Lasting effects of early chronic caffeine feeding on rats' behavior and brain in later life

Pregnant dams were fed a 20% protein diet with caffeine (2 mg/100 g b.wt.), starting on day 9 of gestation. At birth, each dam with 8 assigned pups was fed this diet until weaning, day 22. On day 22, female rats were caged and fed this diet until day 93. Starting on day 93, the caffeine-supplemented diet was replaced with a caffeine-free, 20% protein diet until day 388. Starting on day 31, each animal was placed in a photoactivity cage, and locomotive activity was measured until day 375. On day 388, the animals were killed, and their brains were removed and divided into 7 regions. The weight, DNA, protein and zinc contents, and alkaline phosphatase activity of each region were determined. Locomotive activity of the caffeine-fed group was higher than in the noncaffeine control group. Accumulative activity scores showed 3 subgroups (high, medium, and low) in both groups at day 93. The medium activity subgroup in the caffeine group was greater than the controls from day 72 to day 93. These differences reappeared 5 weeks after cessation of caffeine supplementation and continued until day 375. The differences in activity were minimum in the high and low subgroups. Chronic caffeine intake in early life permanently affected the medium activity subgroup. Furthermore, various regions of the brain were biochemically altered in spite of the feeding of a noncaffeine diet for almost 300 days after caffeine.

Interaction between caffeine intake and heart zinc concentrations in the rat

The purpose of the present study was to determine the levels of zinc in the hearts of growing post-weaning offspring, fetuses and their dams chronically fed caffeine. A further study was conducted to determine the distribution of Zn in subcellular heart fractions affected by acutely injecting caffeine into the veins of the adult rats. After delivery pups were raised on a 200 g protein/kg diet until day 22 of weaning. On day 22 randomly selected male offspring from each litter were divided into two groups. Group 1 was fed continuously on the same diet as a control, whereas in the experimental group offspring were fed on a 200 g protein/kg diet supplemented with caffeine (20 mg/kg). On day 49 the animals were killed and Zn, calcium and magnesium concentrations of the hearts were measured. In the second series of studies pregnant dams were randomly divided into two groups. Group 1 was fed on a 200 g protein/kg diet from day 3 of gestation, whereas in the experimental group dams were fed on the diet supplemented with caffeine. On day 22 of gestation the fetuses were surgically removed. The Zn, Ca and Mg concentrations of hearts of fetuses and dams were determined. In the third phase a caffeine solution was injected into the vein. After 45 min the hearts were removed and Zn levels in the subcellular fractions determined. The hearts of the growing offspring fed on a caffeine-supplemented diet consistently showed decreased Zn and Ca levels compared with the non-caffeine group.(ABSTRACT TRUNCATED AT 250 WORDS)

Atrial natriuretic peptide, arginine vasopressin, aldosterone and plasma renin activity in carbon tetrachloride-induced cirrhosis in rats

The concentrations of atrial natriuretic peptide, arginine vasopressin, aldosterone and the plasma renin activity were studied in male rats with carbon tetrachloride-induced compensated cirrhosis, and the results were compared to those of normal control animals. The rats with cirrhosis exhibited significantly higher plasma renin activity values when compared with the control group. However, plasma concentrations of atrial natriuretic peptide and arginine vasopressin were not significantly different in the two groups. Plasma aldosterone concentrations were significantly higher than those found in the normal control group in approximately 50% of the cirrhotic animals, and were equal to or less than the control values in the rest. This dissociation between plasma renin activity and aldosterone values in some of the cirrhotic animals is interesting and parallels observations made in humans with alcoholic cirrhosis. The results suggest that experimentally induced, apparently compensated cirrhosis may be associated with a perceived decrease in effective circulating volume, and that there is no absolute deficiency of atrial natriuretic peptide in this model of cirrhosis.

The effect of prenatal protein-energy malnutrition on collagen metabolism in fetal bones

We analyzed various biochemical variables of the bones in fetal rats whose dams were protein-energy malnourished. Dams were randomly divided into two groups and fed either a 6% protein diet as a malnourished group or a 20% protein diet as a control, from day 13 of gestation to day 22, when fetuses were removed. Hexosamine and hydroxyproline contents of the calvaria and hexosamine contents of long bones were greater in the malnourished group than in the controls. Sequential extractability of collagen differed among various bones in the malnourished group and controls. The ratio of alpha:beta obtained from SDS-polyacrylamide gel of neutral salt-soluble collagen tended to increase in the long bones and mandible, and decrease in the calvaria and ribs in the malnourished group. Also, the ratio of alpha 1:alpha 2 tended to be lower in the malnourished group than in the control group in all bones. Protein-energy malnutrition during pregnancy has shown to affect biochemical composition of various fetal bones.

The effects of maternal caffeine intake during pregnancy on mineral contents of fetal rat bone

Various levels of maternal caffeine ingestion during pregnancy were investigated to determine whether caffeine will affect the mineral contents of the growing bones of fetal rats. On day 8 of gestation, rat dams were fed with a 20% protein diet supplemented with 0.5 mg, 1 mg, or 2 mg caffeine/100 g of dams body weight as an experimental group and the same without caffeine as a control until day 22 of gestation. Fetuses were removed by cesarean section on day 22 and mandibular bones were removed to study the mineral contents of calcium, phosphorus, magnesium, and zinc. Although the mandible weighed more in the 0.5-mg caffeine group as compared to the controls, an additional increase of caffeine resulted in a decrease in weight. All calcium, magnesium, and zinc contents per bone decreased in the 1- and 2-mg caffeine groups as compared to either controls or 0.5-mg caffeine group, whereas phosphorus stayed relatively constant regardless of the different levels of caffeine intake. When data are expressed as per gram of bone tissue, most of the mineral contents among the groups disappeared suggesting that normal growth and development of the fetal bone are impaired as a results of maternal caffeine intake. Caffeine intake during gestation in the present study indicates that different levels of caffeine intake may exert not only different effects on mineral contents in bone development, but also affect the growth of the fetal bone.

Effects of different levels of caffeine supplemented to the maternal diet on the brains of newborn rats and their dams

At birth, dams with 8 randomly assigned pups were divided into three groups. Dams of group 1 were fed a control diet. Dams of groups 2 and 3 were fed the control diet supplemented with caffeine (1 mg and 2 mg/100 g body weight, respectively). Pups were killed at day 15 and their brains removed. After weighing, brains were analyzed for DNA, protein, cholesterol, zinc and alkaline phosphatase activity. Brain and plasma caffeine levels were also determined on groups 2 and 3. The dams were milked to measure caffeine levels. The brains from the dams were analyzed for the same parameters as the pups. Caffeine levels in group 3 were consistently higher than in group 2. In the pups, body and brain weights were heavier in group 3 than in the controls. Protein and cholesterol concentrations in group 2 were less than either controls or group 3. Alkaline phosphatase activity in group 2 was higher than either controls or group 3. In the dams, DNA concentration in groups 2 and 3 was less than the controls. Protein and cholesterol concentration in group 2 was less than group 3. It was concluded that low levels of caffeine in the maternal diet during lactation could affect various parameters in the newborn brain. These effects were different from those when the dietary caffeine level was doubled. In contrast, the effects of caffeine on brains of the dams were relatively minor.

Atrial natriuretic peptide, arginine vasopressin, and the renin-angiotensin system in carbon tetrachloride-induced hepatitis in rats

The concentrations of atrial natriuretic peptide (ANP), arginine vasopressin (AVP) and hormones of the renin-angiotensin axis were studied in male rats with carbon tetrachloride-induced hepatitis and the results compared to normal control animals. The rats with hepatitis exhibited lower concentrations of ANP, plasma renin activity (PRA), and angiotensin I (AI) than did the control animals. Plasma concentrations of AVP and aldosterone were not significantly different in the two groups. The results suggest that experimental hepatitis is associated with renal hyperperfusion together with reduction in atrial pressures.

Gonadotropin secretion in azotemic male rats--effect of opioid blockade

The role of endogenous opioids in the control of gonadotropin secretion in uremic male rats was investigated using the narcotic antagonist, naloxone. In order to eliminate the effect of weight loss due to uremia-induced anorexia as a cause of previously described altered gonadotropin secretion in uremia, we also studied a group of normal pair-fed control animals who exhibited a weight loss comparable to that of the uremic animals. Naloxone administration had no effect on the basal or LRH-stimulated peak concentrations of LH and FSH in the normal or the uremic rats. Basal and LRH-stimulated gonadotropin responses in the pair-fed rats were comparable to those seen in the normal rats. Similarly, opioid blockade produced no change in the basal or LRH-stimulated gonadotropin responses in the pair-fed animals. Testosterone concentrations were significantly lower in the uremic and pair-fed animals compared to the normal rats. The data suggest that experimental renal failure is not associated with altered opioidergic tone, as it relates to gonadotropin secretion, or to diminished sensitivity of the gonadotroph to LRH stimulation. The decreased testosterone concentration seen in the uremic and pair-fed rats may reflect abnormalities in gonadal hormone secretion due to primary pathology occurring at the level of the gonad. These abnormalities may be reflected as diminished Leydig cell sensitivity to LH. The inappropriately low concentrations of LH in the presence of low testosterone together with normal gonadotropin response to exogenous LRH also suggest an abnormal secretion of endogenous LRH. It is not clear whether this presumed abnormality in LRH secretion is a primary event or is related to decreased testosterone production by the testes in the uremic and pair-fed rats.

Chronic caffeine intake alters the composition of various parts of the brain in young growing rats

Time-pregnant rats were fed a regular laboratory diet until delivery. Litters delivered within an 8-hour period were combined and 8 randomly selected pups were assigned to each dam. Dams were then divided into two groups. Group I received a 20% protein diet. Group II was pair-fed to group I with a 20% protein diet containing caffeine (1 mg/100 g body weight) until day 22 postpartum. On weaning (day 22), only male pups were selected and fed the 20% protein or 20% protein + caffeine diet according to which diet their respective dams had been fed. On day 43, rats were killed and the brains were divided into 6 different areas. DNA, RNA, protein and cholesterol contents were measured. Caffeine supplementation resulted in a decrease in the total brain weight, and DNA and RNA content. DNA value of cortex-midbrain was smaller in the caffeine group whereas the values of medulla oblongata and striatum were greater in comparison with the controls. Caffeine's effects on RNA included an increase in the cerebellum, cortex-midbrain and hippocampus and a decrease in the medulla oblongata. Protein content of cerebellum was increased and of hippocampus decreased due to caffeine supplementation. Cholesterol content of the medulla oblongata and hippocampus was less in the caffeine group than in the control group. The present study shows that chronic caffeine intake during rapid periods of growth influences various parts of the brain in entirely different biochemical manners.

Gestational protein-energy malnutrition affects the composition of developing skins of rat fetuses and their dams

1. Various biochemical variables of the skins of rat dams and their fetuses in which protein-energy malnutrition was induced during pregnancy were analysed. 2. One group of dams was fed on a 200 g protein/kg diet as a control and the other was fed on a 60 g protein/kg diet as an experimental group. Each group of dams was fed from day 13 of gestation until day 22. 3. Water, protein and hexosamine concentrations of the fetal skins in the malnourished group were greater than those in the control group, whereas in the dams' skins, protein concentration was greater in the malnourished group than in the control group. 4. Extractability of collagen with neutral salt and pepsin showed no difference between the groups in the skins of fetuses and dams. The content of type III collagen in the fetal skin did not differ between the groups, but was increased in the malnourished dams' skins compared with that of the control group. 5. The present study showed that protein-energy malnutrition during pregnancy significantly affects the metabolism of the skin in both fetuses and their dams. Furthermore, the skins of fetuses and dams are structurally altered in different ways by this nutritional stress.

Effect of protein malnutrition and maternal caffeine intake on the growth of fetal rat brain

Pregnant dams were divided into two subgroups on day 10 of gestation. Half were fed a 20% protein diet and the other half an 8% protein diet. A second group also subdivided was pair-fed with rats of the first group. Their diet was supplemented with caffeine in amount calculated to provide daily doses of 2 mg/100 g body weight. On days 18, 20, and 22 randomly selected dams were injected with 3H-thymidine intraperitoneally and 1.5 h later their fetuses were delivered surgically in order to determine the rate of DNA synthesis along the gestation. The rest of the fetuses were delivered surgically on day 22. Pups' brains were rapidly removed and DNA, RNA, protein and 3H-thymidine uptake were studied. Average body weights of the fetuses in the caffeine-supplemented control group were smaller than those of the noncaffeine group. Effects of caffeine that were similar in both diet groups included a decrease in brain DNA content and concentration and an increase in brain protein content and concentration. However, the percent decrease and increase, respectively, was different depending on the nutritional status. DNA synthesis was not affected by malnutrition or caffeine supplementation on day 18 of gestation. Caffeine's effect on the rate of DNA synthesis was different on day 20 of gestation depending on nutritional status. Caffeine supplementation resulted in a decrease in DNA synthesis in both groups on day 22 of gestation. These data indicate that caffeine intake during pregnancy produces differential effects on fetal rat brain depending on dietary protein content.

Phenobarbital increases the theophylline requirement of premature infants being treated for apnea

To determine the effect of phenobarbital sodium therapy and subependymal intraventricular hemorrhage (SEp-IVH) on the theophylline requirement of premature infants suffering with apnea and seizure activity, we compared three groups of patients as follows: group 1, those with apnea of prematurity (ten patients); group 2, those with apnea and SEp-IVH (ten patients); and group 3, those with apnea, SEp-IVH, and seizure activity for which they were receiving phenobarbital therapy (nine patients). Patients in groups 1 and 2 required lower dosages and blood levels of theophylline to control their apnea than did those in group 3, who required higher dosages and blood levels of methylxanthines. Theophylline dosages and blood levels did not significantly differ between groups 1 and 2. In group 3, the theophylline requirement for control of apnea was significantly increased after initiation of phenobarbital therapy. There seems to be a direct correlation between the increased requirement for theophylline and concomitant phenobarbital administration. The data suggest that phenobarbital increases theophylline requirement when treating neonatal apnea.

Infarction of the gallbladder--an unusual cause of acute abdomen in the neonate

Infarction of the gallbladder, while rare, must now be included in the growing list of possible and proven complications of umbilical artery catheterization.