Beob Gyun Kim

The effects of dietary chromium (III) picolinate on growth performance, blood measurements, and respiratory rate in pigs kept in high and low ambient temperature.

Three experiments were conducted to investigate the effects of thermal stress and dietary Cr on growth performance and physiological variables in weanling pigs. In Exp. 1, a total of 54 pigs (BW of 5.95 +/- 0.84 kg) were allotted to a 2 x 3 factorial arrangement using 2 ambient temperatures (23.7 or 40.5 degrees C during d 14 to 28 postweaning) and 3 dietary concentrations of Cr (0, 1,000, or 2,000 microg/kg) as Cr(III) picolinate. In Exp. 2, a total of 54 pigs (BW of 5.94 +/- 1.29 kg) were allotted in the same treatment arrangement but with different ambient temperatures (26.5 or 16.0 degrees C during d 14 to 26 postweaning). In Exp. 3, a total of 36 pigs (BW of 6.40 +/- 0.72 kg) were allotted in the same treatment arrangement with ambient temperatures of 25.9 or 13.8 degrees C during d 14 to 28 postweaning. During d 0 to 14 of all experiments, a neutral ambient temperature (NT) was maintained. In Exp. 1, pigs in high ambient temperature (HT) gained less BW (575 vs. 663 g/d; P < 0.001) and consumed less feed (926 vs. 1,074 g/d; P = 0.001) than pigs in NT during d 14 to 28. However, G:F was not affected by ambient temperature (0.623 vs. 0.618 g/g; P = 0.702). Dietary Cr had no effect on growth performance. Pigs in HT had less plasma cortisol (42.0 vs. 53.7 ng/mL; P = 0.012) and glucose (6.68 vs. 6.96 ng/mL; P = 0.018). Respiratory rate of pigs in HT was greater compared with the pigs in NT (114.6 vs. 65.0 breaths/min; P < 0.001) on d 27. In Exp. 2 and 3 (pooled), pigs in low ambient temperature (LT) had decreased G:F (0.636 vs. 0.663 g/g; P < 0.01) associated with a tendency toward a greater ADFI (1,026 vs. 942 g; P = 0.079) during d 14 to 26 (28). Ambient temperature or dietary Cr supplementation had no effect on blood measurements. In Exp. 3, the respiratory rate measured on d 22 and 27 was less (43.2 vs. 54.2 breaths/min and 42.2 vs. 57.0 breaths/min, respectively; P < 0.001) in the pigs in LT than the pigs in NT with no effects of dietary Cr supplementation. These results indicate that growth performance is affected by thermal stress and plasma cortisol is decreased by heat stress, but these effects are not moderated by dietary Cr.

Estrogen receptor α-induced cholecystokinin type A receptor expression in the female mouse pituitary

Estrogen plays a critical role in inducing LH surge. In the pituitary, estrogen receptor alpha (ERalpha) mediates the action of estrogen, while the downstream pathway of ERalpha activation is yet to be elucidated. Here, we report the finding that cholecystokinin type A receptor (CCK-AR) is an ERalpha downstream gene in the mouse anterior pituitary. In the cycling mouse pituitary, the expression of CCK-AR mRNA is markedly higher in the afternoon of proestrus compared with metestrus. Both ovariectomy (OVX) and null mutation of the ERalpha gene completely abolish CCK-AR mRNA expression. Injection of 17beta-estradiol to OVX wild-type mice induces recovery of CCK-AR mRNA expression to levels observed at proestrus, but no such recovery is induced in OVX ERalpha knockout mice. The same pattern of estrogen dependency in inducing CCK-AR mRNA expression was seen in cultured primary anterior pituitary cells, indicating that estrogen directly acts on pituitary cells to induce CCK-AR expression. Immunohistological analysis revealed that more than 80% of gonadotrophs express CCK-AR in the afternoon of proestrus. To test whether CCK-AR mediated the sensitizing effect of estrogen in GnRH-induced LH secretion, primary pituitary cells were primed with estrogen followed by treatment with GnRH in the presence or absence of lorglumide, a CCK-AR antagonist. While both groups secreted LH upon GnRH treatment, lorglumide treatment significantly decreased LH secretion. Taken together, this study finds CCK-AR to be an ERalpha downstream gene in the pituitary and suggests that CCK-AR may play a role in the estrogen sensitization of the pituitary response to GnRH.

The Effects of Dietary Chromium(III) Picolinate on Growth Performance, Vital Signs, and Blood Measurements of Pigs During Immune Stress

This experiment used 24 pigs (26.0xa0kg) to investigate the effects of dietary chromium (Cr) on pigs challenged with lipopolysaccharide (LPS). Following 35xa0days of diet exposure, the immune stress treatments were: (1) phosphate-buffered saline (PBS) injection and no Cr, (2) LPS injection and no Cr, (3) LPS injection and Cr 1,000xa0ppb, and (4) LPS injection and Cr 2,000xa0ppb. At 0xa0h, PBS or LPS was injected intraperitoneally in each pig. During the first 12xa0h post-injection, pigs challenged with LPS lost 951xa0g, while the PBS group gained 170xa0g (pu2009<u20090.001). Compared with the PBS group, LPS-challenged pigs consumed less feed (pu2009<u20090.01) during the first 24xa0h. The LPS group had higher rectal temperature at 2 and 4xa0h and higher respiratory rate at 1.3 and 8.5xa0h than the PBS group (pu2009<u20090.05). Plasma collected at 3xa0h had higher cortisol (pu2009<u20090.001) and lower glucose (pu2009<u20090.05) concentrations in the LPS group than the PBS group. However, supplemental Cr did not affect the response variables. Overall, the LPS challenge affects growth performance, vital signs, and plasma variables, but dietary Cr is unable to moderate stress-related effects associated with an LPS challenge.

Effects of Dietary Chromium (III) Picolinate on Growth Performance, Respiratory Rate, Plasma Variables, and Carcass Traits of Pigs Fed High-Fat Diets

We investigated the effects of supplemental chromium (Cr) as Cr (III) picolinate on pigs fed high-fat diets (HFD) in a 56-day experiment. Thirty-two crossbred pigs (9.6xa0kg) were allotted to four treatments with four blocks and two pigs/pen. Treatments included: (1) low-fat diet (fatu2009<u20093.5%; LFD) with no Cr, (2) HFD (fatu2009>u200930%) with no Cr, (3) HFD with 1,000xa0ppb Cr, and (4) HFD with 2,000xa0ppb Cr. Pigs fed HFD gained weight faster, consumed less, and had lower feed:gain (pu2009<u20090.05). Pigs fed HFD had higher respiration rates than pigs fed LFD on d 41 (pu2009<u20090.05). Plasma insulin on d 14 linearly decreased with Cr (pu2009=u20090.05). Plasma cholesterol concentrations were higher in the pigs fed HFD than those fed LFD, but were largely unaffected by supplemental Cr. Consumption of HFD resulted in greater carcass weight, perirenal fat, and backfat measures (pu2009<u20090.01) compared with the LFD group. Cr resulted in linear reductions of hot carcass weight (pu2009=u20090.08) and average backfat (pu2009<u20090.05). The effects of Cr on carcass fat measures were more pronounced in castrated males than in females. These results indicate that Cr attenuates some effects of a HFD, mainly body fat accretion of pigs, and especially in castrated pigs.

Effects of Chromium(III) Picolinate on Cortisol and DHEAs Secretion in H295R Human Adrenocortical Cells

Dietary chromium(III) picolinate (CrPic) effects on circulating steroid hormones have been reported in various experimental animals. However, direct effects of CrPic on adrenocortical steroidogenesis are uncertain. Therefore, the objective was to determine the effects of CrPic on cortisol and dehydroepiandrosterone sulfate (DHEAs) secretion from H295R cells. In experiment 1, a 24-h exposure to CrPic (0 to 200xa0μM) had both linear (pu2009<u20090.001) and quadratic (pu2009<u20090.001) effects on cortisol secretion from forskolin-stimulated cells with the highest cortisol secretion at 0.1xa0μM of CrPic and the lowest at 200xa0μM of CrPic. In experiment 2, a 48-h exposure to CrPic (200xa0μM) decreased cortisol (pu2009<u20090.07) release from forskolin-stimulated cells during a 24-h collection period. In experiment 3, a 48-h exposure to CrPic (100xa0μM) decreased cortisol (pu2009<u20090.05) and DHEAs (pu2009<u20090.01) from forskolin-stimulated cells during a 24-h sampling period. In experiment 4, a 24-h exposure to forskolin followed by a 24-h exposure to both forskolin and CrPic (100 and 200xa0μM) decreased both cortisol and DHEAs secretion (pu2009<u20090.01). This study suggests that at high concentrations, CrPic inhibits aspects of steroidogenesis in agonist-stimulated adrenocortical cells.