Potential mechanisms linking nutrition and neuroendocrine control of reproduction in the sheep

Nutrition and reproduction are linked in that the nutritional status of an individual influences its reproductive performance, i.e. an individual in negative energy balance will have decreased ability to reproduce. The mechanisms in which nutrition influences reproduction are not understood. My data suggest that reductions in lutenizing hormone secretion resulting from photoperiod-induced increases in sensitivity to testosterone negative feedback may be mediated, at least in part, by elevated neuropeptide Y (NPY), a hypothalamic neuropeptide shown to alter gonadotropin releasing hormone release and potently affect food intake. The results from my second study support our hypothesis that the growth hormone mediated hormone, insulin like growth factor-1 (IGF-1) increases thyroid hormone levels during food deprivation. Furthermore, results from these experiments show that food deprivation has a greater impact on males than females and that the thyroid hormone response to IGF-1 during food deprivation is much greater in females. Though there are likely many humoral and neuroendocrine factors that must act together to coordinate the reproductive response to nutrition, our studies with NPY and IGF-1 have begun to examine some potential mechanisms linking nutrition and neuroendocrine control of reproduction in the sheep

The Effects of Testicular Nerve Transection and Epididymal White Adipose Tissue Lipectomy on Spermatogenesis in Syrian Hamster

Previous investigators demonstrated that epididymal white adipose tissue (EWAT) lipectomy suppressed spermatogenesis and caused atrophy of the seminiferous tubules. EWAT lipectomy, however, may disrupt testicular innervation, which reportedly compromises testicular function. To resolve this confound and better clarify the role of EWAT in spermatogenesis, three experimental groups of hamsters were created in which: i.) the superior and inferior spermatic nerves were transected (SSNx) at the testicular level, ii.) EWAT was extirpated (EWATx), and iii.) testicular nerves and EWAT were left intact (SHAM controls). It was hypothesized that transection of the superior and inferior spermatic nerves would disrupt normal spermatogenesis. The findings indicate a significant reduction in spermatogenic activity and marked seminal tubule atrophy within the EWATx testis, as compared to the SSNx and controls testes, which did not differ significantly from each other. From these data, it is concluded that EWAT, and not testicular innervation, is central to normal spermatogenesis

Hormones, stress and aggression in the spotted hyena (Crocuta crocuta)

Thesis (Ph. D.)--Michigan State University. Department of Zoology, 2009Includes bibliographical references (pages 167-173

Antioxidant and DPPH-Scavenging Activities of Compounds and Ethanolic Extract of the Leaf and Twigs of Caesalpinia bonduc L. Roxb.

Antioxidant effects of ethanolic extract of Caesalpinia bonduc and its isolated bioactive compounds were evaluated in vitro. The compounds included two new cassanediterpenes, 1α,7α-diacetoxy-5α,6β-dihydroxyl-cass-14(15)-epoxy-16,12-olide (1)and 12α-ethoxyl-1α,14β-diacetoxy-2α,5α-dihydroxyl cass-13(15)-en-16,12-olide(2); and others, bonducellin (3), 7,4’-dihydroxy-3,11-dehydrohomoisoflavanone (4), daucosterol (5), luteolin (6), quercetin-3-methyl ether (7) and kaempferol-3-O-α-L-rhamnopyranosyl-(1Ç2)-β-D-xylopyranoside (8). The antioxidant properties of the extract and compounds were assessed by the measurement of the total phenolic content, ascorbic acid content, total antioxidant capacity and 1-1-diphenyl-2-picryl hydrazyl (DPPH) and hydrogen peroxide radicals scavenging activities.Compounds 3, 6, 7 and ethanolic extract had DPPH scavenging activities with IC50 values of 186, 75, 17 and 102 μg/ml respectively when compared to vitamin C with 15 μg/ml. On the other hand, no significant results were obtained for hydrogen peroxide radical. In addition, compound 7 has the highest phenolic content of 0.81±0.01 mg/ml of gallic acid equivalent while compound 8 showed the highest total antioxidant capacity with 254.31±3.54 and 199.82±2.78 μg/ml gallic and ascorbic acid equivalent respectively. Compound 4 and ethanolic extract showed a high ascorbic acid content of 2.26±0.01 and 6.78±0.03 mg/ml respectively.The results obtained showed the antioxidant activity of the ethanolic extract of C. bonduc and deduced that this activity was mediated by its isolated bioactive compounds

Atrazine

prepared by Syracuse Research Corporation under contract no. 205-1999-00024 ; prepared for U.S. Department of Health and Human Services, Public Health Service, Agency for Toxic Substances and Disease Registry."September 2003."Chemical manager(s)/author(s): Alfred Dorsey, Jr. ... [et al.]--P. ix."A toxicological profile for atrazine, draft for public comment was released in September, 2001. This edition supersedes any previously released draft or final profile"--P. iii."This toxicological profile is prepared in accordance with guidelines developed by the Agency for Toxic Substances and Disease Registry (ATSDR) and the Environmental Protection Agency (EPA). The original guidelines were published in the Federal Register on April 17, 1987"--P. v.Includes bibliographical references (p. 179-216)

CHARACTERIZATION OF HYPOTHALAMIC NEUROPEPTIDES IN MAMMALIAN REPRODUCTION

Understanding of regulation of reproduction at the level of the brain changed dramatically with the discovery of reproductive neuropeptides. To date there have been no studies to characterize the distribution of reproductive neuropeptides in the bovine hypothalamus at different stages of the estrus cycle or to determine the physiological effects of peripheral administration of Gonadotropin inhibiting hormone (GnIH) in intact female cattle and ovariohysterectomized bitches. The goal of the first study was to determine distribution and connectivity of kisspeptin, dynorphin, and GnIH in the hypothalami of sexually mature female cattle during the estrous cycle. To this end, hypothalami of female cattle were collected during periestrus and diestrus. The neuroanatomical distribution, synaptic connectivity, and response to different circulating progesterone concentrations suggest these neuropeptides play a pivotal role in the regulation of reproduction in cyclic cattle. Another goal was to test the hypothesis that IV administration of GnIH would decrease serum LH concentrations in post-pubertal heifers. Two studies were carried out to this end. The objective of the first study was to determine whether IV GnIH administration would decrease basal serum LH concentrations. The objective of the second study was to determine whether continuous IV administration of GnIH during the expected time of the LH surge had an effect on serum LH concentrations and ovulation. Results suggest that exogenous administration of GnIH decreases basal LH concentrations but is not able to suppress the surge release of LH or ovulation in post-pubertal heifers. Finally, the objective of the third study was to determine the effects of IV administration of GnIH on serum LH concentrations in ovariohysterectomized bitches as a potential alternative to surgical sterilization. Results suggest that IV administration of GnIH is not able to suppress serum LH concentrations in the ovariohysterectomized bitch. In summary, expression of kisspeptin, dynorphin, and GnIH changes with progesterone concentrations in sexually mature female cattle. In addition, exogenous administration of GnIH affects basal plasma concentrations of LH but not LH surge characteristics in sexually mature female cattle. It also appears that exogenous administration of GnIH does not affect plasma LH concentrations in ovariohysterectomized adult bitches

Growth hormone co-treatment in superovulation programmes

The role of insulin-like growth factor I (IGF-I) in modulating the granulosa cell response to gonadotrophins is now well established and recent work has suggested that growth hormone (GH) administration increases intraovarian IGF-I production. Following the successful use of GH administration in patients who had previously had a poor response to clomiphene citrate and human menopausal gonadotrophins (hMG) prior to in-vitro fertilisation and embryo transfer, twenty women were recruited into a prospective, double blind, placebo controlled trial of GH co-treatment. Women with PCO developed more follicles and had more oocytes collected but the women with normal ovaries showed no response. Circulating IGF-I concentrations rose during GH treatment but follicular fluid concentrations were significantly lower than serum. IGF-II concentrations did not alter with GH treatment. Gonadotrophin releasing-hormone analogues are associated with increased requirements for hMG and twenty eight women were subsequently recruited into a randomised, placebo controlled study using GH in combination with buserelin and hMG. Women who received GH and who had ultrasound diagnosed PCO had an improved outcome, however there was a substantial placebo effect. Women with normal ovaries did not demonstrate any effect of GH treatment. IGF-I concentrations rose with GH administration but not with hMG alone. Follicular fluid concentrations of IGF-I were lower than serum concentrations, suggesting that IGF-I is not synthesised in the ovary. As women with PCO formed the responsive group we wished to establish a biochemical marker for the condition. 11[beta]-hydroxyandrostenedione (11[beta]-OH-A4) concentrations had been suggested to be abnormal in PCO. We therefore developed an in-house method for determining the concentrations of 11[beta]-OH-A4 in serum and follicular fluid. We were, however, unable to define differences in concentrations between women with normal and polycystic ovaries and concluded that 11[beta]-OH-A4 was not a suitable marker for PCO