Neuropeptidomics of the Supraoptic Rat Nucleus

The mammalian supraoptic nucleus (SON) is a neuroendocrine center in the brain regulating a variety of physiological functions. Within the SON, peptidergic magnocellular neurons that project to the neurohypophysis (posterior pituitary) are involved in controlling osmotic balance, lactation, and parturition, partly through secretion of signaling peptides such as oxytocin and vasopressin into the blood. An improved understanding of SON activity and function requires identification and characteriza-tion of the peptides used by the SON. Here, small-volume sample preparation approaches are optimized for neuropeptidomic studies of isolated SON samples ranging from entire nuclei down to single magnocellular neurons. Unlike most previous mammalian peptidome studies, tissues are not im-mediately heated or microwaved. SON samples are obtained from ex vivo brain slice preparations via tissue punch and the samples processed through sequential steps of peptide extraction. Analyses of the samples via liquid chromatography mass spectrometry and tandem mass spectrometry result in the identification of 85 peptides, including 20 unique peptides from known prohormones. As the sample size is further reduced, the depth of peptide coverage decreases; however, even from individually isolated magnocellular neuroendocrine cells, vasopressin and several other peptides are detected

A Potential New Pathway for Staphylococcus aureus Dissemination: The Silent Survival of S. aureus Phagocytosed by Human Monocyte-Derived Macrophages

Although considered to be an extracellular pathogen, Staphylococcus aureus is able to invade a variety of mammalian, non-professional phagocytes and can also survive engulfment by professional phagocytes such as neutrophils and monocytes. In both of these cell types S. aureus promptly escapes from the endosomes/phagosomes and proliferates within the cytoplasm, which quickly leads to host cell death. In this report we show that S. aureus interacted with human monocyte-derived macrophages in a very different way to those of other mammalian cells. Upon phagocytosis by macrophages, S. aureus persisted intracellularly in vacuoles for 3–4 days before escaping into the cytoplasm and causing host cell lysis. Until the point of host cell lysis the infected macrophages showed no signs of apoptosis or necrosis and were functional. They were able to eliminate intracellular staphylococci if prestimulated with interferon-γ at concentrations equivalent to human therapeutic doses. S. aureus survival was dependent on the alternative sigma factor B as well as the global regulator agr, but not SarA. Furthermore, isogenic mutants deficient in α-toxin, the metalloprotease aureolysin, protein A, and sortase A were efficiently killed by macrophages upon phagocytosis, although with different kinetics. In particular α-toxin was a key effector molecule that was essential for S. aureus intracellular survival in macrophages. Together, our data indicate that the ability of S. aureus to survive phagocytosis by macrophages is determined by multiple virulence factors in a way that differs considerably from its interactions with other cell types. S. aureus persists inside macrophages for several days without affecting the viability of these mobile cells which may serve as vehicles for the dissemination of infection

Endothelin-1 as a neuropeptide: neurotransmitter or neurovascular effects?

Endothelin-1 (ET-1) is an endothelium-derived peptide that also possesses potent mitogenic activity. There is also a suggestion the ET-1 is a neuropeptide, based mainly on its histological identification in both the central and peripheral nervous system in a number of species, including man. A neuropeptide role for ET-1 is supported by studies showing a variety of effects caused following its administration into different regions of the brain and by application to peripheral nerves. In addition there are studies proposing that ET-1 is implicated in a number of neural circuits where its transmitter affects range from a role in pain and temperature control to its action on the hypothalamo-neurosecretory system. While the effect of ET-1 on nerve tissue is beyond doubt, its action on nerve blood flow is often ignored. Here, we review data generated in a number of species and using a variety of experimental models. Studies range from those showing the distribution of ET-1 and its receptors in nerve tissue to those describing numerous neurally-mediated effects of ET-1

Endothelin-1 and endothelin receptors in the basilar artery of the capybara.

Little is known about cerebral vasculature of capybara, which seems may serve as a natural model of studying changes in cerebral circulation due to internal carotid artery atrophy at animal sexual maturation. This is the first study of the light- and electron-immunocytochemical localisation of endothelin-1 (ET-1) and ETA and ETB endothelin receptors in the basilar artery of capybaras (6 to 12-month-old females and males) using an ExtrAvidin detection method. All animals examined showed similar patterns of immunoreactivity. Immunoreactivity for ET-1 was detected in the endothelium and adventitial fibroblasts, whilst immunoreactivity for ETA and ETB receptors was present in the endothelium, vascular smooth muscle, perivascular nerves and fibroblasts. In endothelial cells immunoreactivity to ET-1 was pronounced in the cytoplasm or on the granular endoplasmic reticulum. Similar patterns of immunolabelling were observed for ETA and ETB receptors, though cytoplasmic location of clusters of immunoprecipitate seems dominant. These results suggest that the endothelin system is present throughout the wall of the basilar artery of capybara

Endothelin-1 and endothelin receptors in the basilar artery of the capybara.

Little is known about cerebral vasculature of capybara, which seems may serve as a natural model of studying changes in cerebral circulation due to internal carotid artery atrophy at animal sexual maturation. This is the first study of the light- and electron-immunocytochemical localisation of endothelin-1 (ET-1) and ETA and ETB endothelin receptors in the basilar artery of capybaras (6 to 12-month-old females and males) using an ExtrAvidin detection method. All animals examined showed similar patterns of immunoreactivity. Immunoreactivity for ET-1 was detected in the endothelium and adventitial fibroblasts, whilst immunoreactivity for ETA and ETB receptors was present in the endothelium, vascular smooth muscle, perivascular nerves and fibroblasts. In endothelial cells immunoreactivity to ET-1 was pronounced in the cytoplasm or on the granular endoplasmic reticulum. Similar patterns of immunolabelling were observed for ETA and ETB receptors, though cytoplasmic location of clusters of immunoprecipitate seems dominant. These results suggest that the endothelin system is present throughout the wall of the basilar artery of capybara