Safety of an oxygen-coordinated niacin-bound chromium(III) complex (NBC): II. Developmental toxicity study in rats.

The objective of the present study was to evaluate the teratogenic potential of a novel oxygen-coordinated niacin-bound chromium complex (NBC) in Sprague-Dawley rats. Due to its potential to affect fat synthesis and reduce food intake, processes which are often crucial in normal fetal development, this teratology study was undertaken as part of a multi-generation reproductive investigation. The animals in this study were selected randomly after weaning from each F(2b) litter of the F1 generation from the two-generation reproductive toxicity study. To start the teratology study, Sprague-Dawley rat pups ( approximately 30/sex/group) from the F(2b) generation were allowed to grow up to 10-12 weeks of age before mating. The rats in treatment group were exposed directly to NBC through feed. The dietary exposure levels were the same as those employed for the two-generation reproductive toxicity study, viz. 4, 15, or 60 ppm. Following mating at maturity, the pregnant rats were observed daily for clinical signs of adverse effects, and body weight and feed consumption were recorded. On the day 20th of the gestation, animals were subjected to a necropsy and caesarean section to examine the uterus, ovaries and fetuses for assessment of different parameters of pregnancy and embryo-fetal defects. In this study, no indications of maternal toxicity, adverse effects on the parameters evaluated for the gravid uteri, external abnormalities in the fetuses, soft tissue abnormalities in the fetuses, or skeletal abnormalities in the fetuses were noted. Based on the results of this developmental toxicity study, NBC was found to benon-teratogenic in Sprague-Dawley rat, at the dietary exposure levels of 4, 15, and 60 ppm, equivalent to the dose levels of 0.50, 2.0, or 8.0mg/kg/day, respectively.

Safety of a novel oxygen-coordinated niacin-bound chromium(III) complex (NBC): I. Two-generation reproduction toxicity study.

The objective of this study was to evaluate the effects of a novel oxygen-coordinated niacin-bound chromium(III) complex (NBC) on the reproductive systems of male and female rats, the postnatal maturation and reproductive capacity of their offspring, and possible cumulative effects through multiple generations. Sprague-Dawley rats were maintained on feed containing NBC at dose levels of 0, 4, 15, or 60ppm for 10weeks prior to mating, during mating, and, for females through gestation and lactation, across two generations. For the parents (F(0) and F(1)) and the offspring (F(1) and F(2a)), reproductive parameters such as fertility and mating, gestation, parturition, litters, lactation, sexual maturity and development of offspring were assessed. Results from the current study indicated that dietary exposure of NBC to parental male and female rats of both (F(0) and F(1)) the generations during the premating and mating periods, for both sexes, and during gestation and lactation in case of female rats, did not cause any significant incidence of mortality or abnormal clinical signs. Compared to respective controls, NBC exposure did not affect reproductive performance as evaluated by sexual maturity, fertility and mating, gestation, parturition, litter properties, lactation and development of the offspring. Based on the findings of this study, the parental as well as the offspring no-observed-adverse-effect level for NBC was determined to be greater than 60ppm in diet or equivalent to 7.80 and 8.31mg/kg body weight/day in male and female rats, respectively.

Dopamine and Abeta-induced stress signaling and decrements in Ca2+ buffering in primary neonatal hippocampal cells are antagonized by blueberry extract.

We have shown previously that dietary blueberry (BB) extract supplementation (S) reversed several parameters of neuronal and behavioral (e.g., cognition) aging in rodents. Additionally, findings indicate that COS-7 cells transfected with muscarinic receptor subtypes (e.g., M1) showed decrements in Ca;{2+} clearance following depolarization (Ca;{2+} Recovery time, Ca;{2+}RT) that were antagonized by BB. Since it has been postulated that at least part of the loss of cognitive function in aging may be dependent upon a dysregulation in calcium homeostasis (i.e., Ca;{2+}RT), we assessed whether: a) Ca;{2+}RT would be altered in dopamine (DA)- or amyloid beta (Abeta)-exposed cultured primary hippocampal neuronal cells (HNC), and b) BB pre-treatment of the cells would prevent these deficits. Thus, control or BB (0.5 mg/ml)-treated HNC were exposed to DA (0.1 mM, 2 hrs), Abeta(40) (25 microM, 24 hrs), Abeta(42) (25 microM, 24 hrs), and Abeta(25-35) (25 microM, 24 hrs), and Ca;{2+}RT following KCl-induced depolarization assessed. Ca;{2+}RT was assessed as the % of HNC showing recovery to 50%-70% of control at 5, 10, or 15 min after depolarization. Results indicated that DA significantly lowered Ca;{2+}RT in the HNC at all time points examined after depolarization. However, BB treatment selectively prevented these declines in Ca;{2+}RT. In the case of Abeta, the greatest effects on Ca;{2+}RT were seen when the hippocampal cells were Abeta(42)-treated. These effects were antagonized by BB treatment. Abeta(40) produced fewer deficits on Ca;{2+}RT than those seen when the HNC were pre-treated with either A;{2+}(42) or A;{2+}(25-35), but BB was relatively ineffective in antagonizing the deficits in Ca;{2+}RT produced by A;{2+}(40) or A;{2+}(25-35). Additional analyses indicated that BBs may be exerting their protective effects in the hippocampal cells by altering levels of phosphorylated MAPK, PKCgamma, and phosphorylated CREB. Therefore it appears that at least part of the protective effect of BBs may involve alterations in stress signaling.

Expression of calcium channel alpha1A mRNA and protein in the leaner mouse (tgla/tgla) cerebellum.

Homozygous leaner mice carry an autosomal recessive mutation in the Ca2+ channel subunit gene, alpha1A, causing them to exhibit severe ataxia, petit-mal-like epilepsy and a myoclonus-like movement disorder. Expression of alpha1A mRNA in cerebella from 20-day-old homozygous leaner mice was compared to control mice, using in situ hybridization histochemistry. Expression of alpha1A protein was examined in cerebella from 20-day-old homozygous leaner and control mice using immunocytochemistry. No differences in either mRNA or protein expression of the alpha1A subunit were observed when homozygous leaner mice were compared to age-matched controls. Therefore, functional alterations in P/Q-Type Ca2+ channels containing the alpha1A subunit need to be explored to further understand the relationship of mutations in the alpha1A gene to the pathogenesis of the neurologic disorders occurring in leaner mice.