A novel hypothalamic peptide, pituitary adenylate cyclase activating peptide, modulates Sertoli cell function in vitro.

Pituitary adenylate cyclase-activating peptide (PACAP), a novel hypothalamic peptide that has been shown to exist in several tissues including the testis, was examined for its effects on cultured rat Sertoli cells. PACAP stimulates cAMP accumulation in Sertoli cells cultured from 15-day-old rats in the presence or absence of methylisobutylxanthine, a phosphodiesterase inhibitor, and in the presence of pertussis toxin, a blocker of the adenylate cyclase inhibitory pathway. Maximal stimulation, which is 20-40% of that attainable with FSH, occurs at PACAP concentrations of 10 nM: the ED50 is approximately 100 pM. The ability of PACAP to stimulate Sertoli cell cAMP declines with increasing age of donor animals (15-60 days of age) in a fashion similar to the FSH effect. PACAP stimulation of Sertoli cell cAMP accumulation is additive with submaximal, but not maximal, concentrations of FSH or forskolin. PACAP also stimulates the secretion of lactate, estradiol, and inhibin in a concentration-dependent manner. The stimulation of Sertoli cell cAMP accumulation by PACAP is not altered by a vasoactive intestinal peptide antagonist, and vasoactive intestinal peptide alone does not stimulate cAMP accumulation, indicating that PACAP is not acting via vasoactive intestinal peptide receptors. Further experiments are needed to determine whether PACAP is synthesized within the testis and if so, in which cell types; however, the present data clearly demonstrate that PACAP can modulate Sertoli cell function in vitro.     

Growth of Rhodospirillum rubrum on synthesis gas: conversion of CO to H2 and poly-beta-hydroxyalkanoate

To examine the potential use of synthesis gas as a carbon and energy source in fermentation processes, Rhodospirillum rubrum was cultured on synthesis gas generated from discarded seed corn. The growth rates, growth and poly-beta-hydroxyalkanoates (PHA) yields, and CO oxidation/H(2) evolution rates were evaluated in comparison to the rates observed with an artificial synthesis gas mixture. Depending on the gas conditioning system used, synthesis gas either stimulated or inhibited CO-oxidation rates compared to the observations with the artificial synthesis gas mixture. Inhibitory and stimulatory compounds in synthesis gas could be removed by the addition of activated charcoal, char-tar, or char-ash filters (char, tar, and ash are gasification residues). In batch fermentations, approximately 1.4 mol CO was oxidized per day per g cell protein with the production of 0.75 mol H(2) and 340 mg PHA per day per g cell protein. The PHA produced from R. rubrum grown on synthesis gas was composed of 86% beta-hydroxybutyrate and 14% beta-hydroxyvalerate. Mass transfer of CO into the liquid phase was determined as the rate-limiting step in the fermentation.     

TNF receptors 1 and 2 exert distinct region‐specific effects on striatal and hippocampal grey matter volumes (VBM) in healthy adults

Tumour necrosis factor alpha (TNFα) has been implicated in the pathophysiology of neurodegenerative and neuropsychiatric disease, with research highlighting a role for TNFα in hippocampal and striatal regulation. TNFα signals are primarily transduced by TNF receptors 1 and 2 (TNFR1 and TNFR2), encoded by TNFRSF1A and TNFRSF1B, which exert opposing effects on cell survival (TNFR1, neurodegenerative; TNFR2, neuroprotective). We therefore sought to explore the respective roles of TNFR1 and TNFR2 in the regulation of hippocampal and striatal morphology in an imaging genetics study. Voxel‐based morphometry was used to analyse the associations between TNFRSF1A (rs4149576 and rs4149577) and TNFRSF1B (rs1061624) genotypes and grey matter structure. The final samples comprised a total of 505 subjects (mean age = 33.29, SD = 11.55 years; 285 females and 220 males) for morphometric analyses of rs1061624 and rs4149576, and 493 subjects for rs4149577 (mean age = 33.20, SD = 11.56 years; 281 females and 212 males). Analyses of TNFRSF1A single nucleotide polymorphisms (SNPs) rs4149576 and rs4149577 showed highly significant genotypic associations with striatal volume but not the hippocampus. Specifically, for rs4149576, G homozygotes were associated with reduced caudate nucleus volumes relative to A homozygotes and heterozygotes, whereas for rs4149577, reduced caudate volumes were observed in C homozygotes relative to T homozygotes and heterozygotes. Analysis of the TNFRSF1B SNP rs1061624 yielded a significant association with hippocampal but not with striatal volume, whereby G homozygotes were associated with increased volumes relative to A homozygotes and heterozygotes. Our findings indicate a role for TNFR1 in regulating striatal but not hippocampal morphology, as well as a complementary role for TNFR2 in hippocampal but not in striatal morphology.     

Disruption of Wave-associated Rac GTPase-activating Protein (Wrp) Leads to Abnormal Adult Neural Progenitor Migration Associated with Hydrocephalus

Hydrocephalus is the most common developmental disability and leading cause of brain surgery for children. Current treatments are limited to surgical intervention, as the factors that contribute to the initiation of hydrocephalus are poorly understood. Here, we describe the development of obstructive hydrocephalus in mice that are null for Wrp (Srgap3). Wrp is highly expressed in the ventricular stem cell niche, and it is a gene required for cytoskeletal organization and is associated with syndromic and psychiatric disorders in humans. During the postnatal period of progenitor cell expansion and ventricular wall remodeling, loss of Wrp results in the abnormal migration of lineage-tagged cells from the ventricular region into the corpus callosum. Within this region, mutant progenitors appear to give rise to abnormal astroglial cells and induce periventricular lesions and hemorrhage that leads to cerebral aqueductal occlusion. These results indicate that periventricular abnormalities arising from abnormal migration from the ventricular niche can be an initiating cause of noncommunicating hydrocephalus.     

No evidence for parental imprinting of mouse 22q11 gene orthologs

Non-Mendelian factors may influence central nervous system (CNS) phenotypes in patients with 22q11 Deletion Syndrome (22q11DS, also known as DiGeorge or Velocardiofacial Syndrome), and similar mechanisms may operate in mice carrying a deletion of one or more 22q11 gene orthologs. Accordingly, we examined the influence of parent of origin on expression of 25 murine 22q11 orthologs in the developing and mature CNS using single nucleotide polymorphism (SNP)-based analysis in interspecific crosses and quantification of mRNA in a murine model of 22q11DS. We found no evidence for absolute genomic imprinting or silencing. All 25 genes are biallelically expressed in the developing and adult brains. Furthermore, if more subtle forms of allelic biasing are present, they are very small in magnitude and most likely beyond the resolution of currently available quantitative approaches. Given the high degree of similarity of human 22q11 and the orthologous region of mmChr16, genomic imprinting most likely cannot explain apparent parent-of-origin effects in 22q11DS.     

Isolation and culture of FSH responsive Sertoli cells.

Methods for the isolation and culture of enriched populations of Sertoli cells from 20-60 day old rats are described. The identity of the Sertoli cells was verified by bright light and electron microscopy. Freshly isolated Sertoli cells specifically bound follicle stimulating hormone (FSH) but not luteinizing hormone (LH) and responded to FSH stimulation with dramatic increase in cyclic AMP level. Isolated Sertoli cells, maintained in culture for 11 days, showed no evidence of proliferation but retained their characteristic ultrastructural features and FSH binding ability. Incubation of cultured cells with FSH resulted in a significant stimulation of cyclic AMP and androgen binding protein (ABP). Since the freshly isolated or cultured cells were predominantly (greater than 80%) Sertoli cells, these results provide direct evidence that the Sertoli cells represent a primary target site for FSH activity in the testes. The culture method also provides a valuable in vitro model for the study of chronic effects of various agents on the Sertoli cell.