The physiological role of arcuate kisspeptin neurons in the control of reproductive function in female rats.

Kisspeptin plays a pivotal role in pubertal onset and reproductive function. In rodents, kisspeptin perikarya are located in 2 major populations: the anteroventral periventricular nucleus and the hypothalamic arcuate nucleus (ARC). These nuclei are believed to play functionally distinct roles in the control of reproduction. The anteroventral periventricular nucleus population is thought to be critical in the generation of the LH surge. However, the physiological role played by the ARC kisspeptin neurons remains to be fully elucidated. We used bilateral stereotactic injection of recombinant adeno-associated virus encoding kisspeptin antisense into the ARC of adult female rats to investigate the physiological role of kisspeptin neurons in this nucleus. Female rats with kisspeptin knockdown in the ARC displayed a significantly reduced number of both regular and complete oestrous cycles and significantly longer cycles over the 100-day period of the study. Further, kisspeptin knockdown in the ARC resulted in a decrease in LH pulse frequency. These data suggest that maintenance of ARC-kisspeptin levels is essential for normal pulsatile LH release and oestrous cyclicity.

Prophylactic effect of dietary glutamine supplementation on interleukin 8 and tumour necrosis factor alpha production in trinitrobenzene sulphonic acid induced colitis.

BACKGROUND: It is well established that glutamine supplemented elemental diets result in less severe intestinal damage in experimental colitis. However, few studies have examined the mode of action of glutamine in reducing intestinal damage. AIMS: To examine the effects of glutamine supplemented elemental diets on the potent inflammatory cytokines interleukin 8 (IL-8) and tumour necrosis factor alpha (TNF-alpha) in trinitrobenzene sulphonic acid (TNBS) induced colitis which presents with both acute and chronic features of ulcerative colitis. METHODS: Sprague-Dawley rats were randomised into three dietary groups and fed 20% casein (controls), or 20% casein supplemented with either 2% glutamine (2% Gln) or 4% glutamine (4% Gln). After two weeks they received intracolonic TNBS to induce colitis. RESULTS: Both Gln groups of rats gained more weight than the control group (p < 0.05) which had progressive weight loss. Colon weight, macroscopic, and microscopic damage scores for the Gln groups were lower than in the control group (p < 0.05). IL-8 and TNF-alpha concentrations in inflamed colonic tissues were lower in the Gln groups than in the control group (p < 0.05), and correlated well with disease severity. Bacterial translocation was lower both in incidence (p < 0.05) and in the number of colony forming units (p < 0.05) for the Gln groups, than in the control group. With respect to all indices studied, the 4% Gln group performed better than did the 2% Gln group. CONCLUSION: Prophylactic glutamine supplementation modulates the inflammatory activities of IL-8 and TNF-alpha in TNBS induced colitis.

Nucleoside-nucleotide-free diet suppresses cytokine production and contact sensitivity responses in rats with trinitrobenzene sulphonic acid-induced colitis.

We examined the effects of dietary nucleoside-nucleotide mixture on synthesis of inflammatory cytokines, interleukin-8 and tumor necrosis factor-alpha, in sensitized and nonsensitized colitic rats. Sensitized and nonsensitized colitic rats that were fed a nucleoside-nucleotide mixture had greater colonic weight and macroscopic and microscopic damage scores than nucleoside-nucleotide-free sensitized and nonsensitized colitic rats. Increased colonic tumor necrosis factor-alpha and interleukin-8 concentrations were associated with increased colonic inflammation and ulceration in the nucleoside-nucleotide mixture-fed group. There was also increased ear thickness in the nucleoside-nucleotide mixture-fed sensitized and nonsensitized colitic rats, which correlated highly with increased tumor necrosis factor-alpha and interleukin-8 levels in the ear lobes. Nucleoside-nucleotide-free diets may suppress cytokine secretion, thereby reducing colonic damage and contact sensitivity responses in colitic rats.

Blood glucose responses to mixed Ghanaian diets in healthy adult males.

The blood glucose responses to five Ghanaian carbohydrate sources, unripe plantain, Ga kenkey, Gari, rice and yam, as part of mixed meals were determined in ten healthy young nondiabetic adult males aged 25.6 +/- 2.6 years with a BMI of 20.9 +/- 2.4 kg/m2. Ga kenkey showed the least changes in blood glucose responses as measured by the glycemic index. Yam exhibited the least favourable blood glucose responses. Significant difference were observed between the glycemic indices of kenkey and yam; Kenkey and gari (p < 0.01); rice and yam, plantain and yam (p < 0.05). Further studies of these carbohydrate sources are required in diabetics to ascertain their suitability as carbohydrate sources in Ghanaian diabetics.

Modulation of age-related changes in immune functions of protein-deficient senescence-accelerated mice by dietary nucleoside-nucleotide mixture supplementation.

In the present study we examined the immune-enhancing effect of a nucleoside-nucleotide mixture on the non-specific T-cell immune functions of senescence-accelerated mice (SAM) fed on a low-protein diet. The immune functions studied were in vitro thymic and splenic cell lymphoproliferative responses to phytohaemagglutinin, lipopolysaccharide and concanavalin A and their production of interleukin-2 (IL-2) and interferon-gamma (INF-gamma) in response to mitogen stimulation. SAMP8 mice aged 3 and 6 months were used. In each age group, mice were fed on diets containing either 50 g casein/kg, 50 g casein/kg supplemented with 5 g nucleoside-nucleotide mixture/kg or 200 g casein/kg for 3 weeks. The supplemented 3- and 6-month-old mice had higher (P < 0.05) thymic and splenic cell counts compared with the low-protein group. In both age groups of mice, concanavalin A induced higher (P < 0.05) total thymic and splenic lymphoproliferative responses for the nucleoside-nucleotide mixture-supplemented group compared with the 50 g casein/kg dietary groups. Thymic and splenic production of IL-2 was higher for the 3-month-old mice in both the supplemented and the 200 g casein/kg dietary groups. INF-gamma production in the supplemented 3-month-old group and the 6-month-old 200 g casein/kg dietary group was higher (P < 0.05) compared with the other groups. Overall the supplemented 3-month-old mice exhibited both higher lymphoproliferative responses and production of cytokines compared with the supplemented 6-month-old mice. The results indicate that early nucleoside-nucleotide mixture supplementation may enhance the immune response in protein-deprived SAMP8 mice.