The Human Microbiome Project (HMP), funded as an initiative of the NIH Roadmap for Biomedical Research (http://nihroadmap.nih.gov), is a multi-component community resource. The goals of the HMP are: (1) to take advantage of new, high-throughput technologies to characterize the human microbiome more fully by studying samples from multiple body sites from each of at least 250 “normal” volunteers; (2) to determine whether there are associations between changes in the microbiome and health/disease by studying several different medical conditions; and (3) to provide both a standardized data resource and new technological approaches to enable such studies to be undertaken broadly in the scientific community. The ethical, legal, and social implications of such research are being systematically studied as well. The ultimate objective of the HMP is to demonstrate that there are opportunities to improve human health through monitoring or manipulation of the human microbiome. The history and implementation of this new program are described here.

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Expression and estrogen regulation of the genes for nitric-oxide (NO)-synthesizing enzymes (NO synthase, NOS) were investigated by in situ hybridization. This study focused on regions of the hypothalamus that contain estrogen receptors and regulate specific neuroendocrine functions related to female sexual behavior and food intake, among others. Ovariectomized (OVX) rats were treated with vehicle or 3 µg/100 g estradiol benzoate (EB) for 7 days. Brains were sectioned and hybridized with antisense riboprobes for neuronal NOS, macrophage NOS and endothelial NOS. In the hypothalamus, mRNA was clearly detectable only for the neuronal NOS with the probes used. A strong hybridization signal was observed in the supraoptic paraventricular and ventromedial nuclei (SON, PVN and VMN, respectively). Quantitative analysis showed an increase in neuronal NOS mRNA in the VMN of the OVX rats treated with EB. The increase was mainly in the ventrolateral aspect of the VMN. No significant changes were observed in the hypothalamic SON and PVN. The data suggest that the expression of neuronal NOS mRNA in VMN can be regulated by estrogen.

Cytosine arabinoside (AraC) is a nucleoside analog that produces signi®cant neurotoxicity in cancer patients. The mechanism by which AraC causes neuronal death is a matter of some debate because the conventional understanding of AraC toxicity requires incorporation into newly synthesized DNA. Here we demonstrate that AraC-induced apoptosis of cultured cerebral cortical neurons is mediated by oxidative stress. AraC-induced cell death was reduced by treatment with several different free-radical scavengers (N-acetyl-Lcysteine, dipyridamole, uric acid, and vitamin E) and was increased following depletion of cellular glutathione stores. AraC induced the formation of reactive oxygen species in neurons as measured by an increase in the¯uorescence of the dye 5-(6)-carboxy-2 H ,7 H -dichlorodihydro¯uorescein diacetate. AraC produced DNA single-strand breaks as measured by single-cell gel electrophoresis and the level of DNA strand breakage was reduced by treatment with the free radical scavengers. These data support a model in which AraC induces neuronal apoptosis by provoking the generation of reactive oxygen species, causing oxidative DNA damage and initiating the p53-dependent apoptotic program. These observations suggest the use of antioxidant therapies to reduce neurotoxicity in AraC chemotherapeutic regimens.

Castration of male and female rats resulted in a marked rise in serum LH. The rise in serum LH was partially or completely prevented by injection of prolactin (Prl), by implantation of a small amount of Prl in the median eminence (ME), by grafting 2 anterior pituitaries (APs) underneath the kidney capsule, or by transplantation of a Prl-secreting pituitary tumor underneath the skin. The larger pituitary tumor transplants secreted more Prl and were more effective in reducing LH release than the smaller tumors which secreted less Prl. Suppression of LH release generally was greater during the earlier than in the later phases of the different treatments. The pituitary LH response to synthetic LH-RH was the same in ovariectomized rats with or without pituitary grafts, and the decrease in hypothalamic LH-RH after orchidectomy was prevented by pituitary grafts. These results indicate that Prl can depress LH release after castration and that these effects are mediated via the hypothalamus.

Oxidative stress has been implicated in various neurodegenerative diseases. There is substantial evidence indicating that gonadal hormones can affect neuronal cell survival via both a genomic as well as a non-genomic mode of action. In the present study, the potential protective activity of testosterone on neuronal cells was investigated by using an in vitro/ex vivo model. Cerebellar granule cells (CGC) were prepared from 7-day-old rats which had been treated with a single dose of oil or testosterone propionate on postnatal day 3. After 7 days in culture, cells were exposed to oxidative challenges, including hydrogen peroxide and the nitric oxide donor S-nitrosocysteine (SNOC), which can induce CGC death via apoptosis. Colchicine, which causes apoptosis via a different mechanism, was also used. The cells were monitored for apoptotic morphology by propidium iodide and TUNEL staining. Additionally, the presence of chromatin fragmentation was determined. CGC obtained from testosterone-treated rats were found to be more resistant to hydrogen peroxide and nitric oxide toxicity, as shown by a 75 and 45% decrease in apoptotic cells, respectively. In contrast, the susceptibility to colchicine was not modified. As CGC from testosterone-treated pups were selectively protected from oxidative stress, different components of the antioxidant defence systems were analysed. A twofold increase in the activity of catalase and superoxide dismutase was found in the CGC prepared from testosterone-treated rats. These results suggest that in vivo treatment with androgens render CGC less vulnerable to oxidative stress-induced apoptosis by potentiating antioxidant defences.

In post-partum lactating rats, sucking by the young was associated with high prolactin release and maintenance of lactation but severe inhibition of LH and FSH release and suspension of oestrous cycles. Shortly after the pups were removed on day 22 post partum LH and FSH release returned to normal and oestrous cycles resumed. Twice-daily injections of ergocornine methanesulphonate (ERG) into mothers beginning at 5 or 7 days post partum, resulted in sustained inhibition of prolactin release and diminished mild secretion. By frequent exchange of pups between control and ERG-treated mothers, it was possible to maintain vigorous sucking and almost normal pup growth despite low serum prolactin levels and diminished lactation. In these rats, serum levels of LH remained low during 11 or more days of treatment with ERG, but serum FSH was consistently higher than in untreated control mothers. After 11 or more days of ERG treatment, most rats showed a return to normal LH and FSH release and resumption of oestrous cycles. These results suggest (a) that the sucking stimulus rather than high prolactin levels in the circulation is mainly responsible for inhibition of LH and FSH release during the first 11 days post partum, (b) that the sucking stimulus acts to increase prolactin and inhibit LH release by separate hypothalamic mechanisms, and (c) that administration of ERG results in diminished prolactin release and lactation, and in increased release of FSH and subsequently of LH with earlier resumption of oestrous cycles.

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