Periventricular

High amounts of somatostatin are found in the CNS, the peripheral nervous system, the gut and the endocrine pancreas whereas the kidneys, adrenals, thyroid, submandibular glands, prostate and placenta produce rather low amounts. In particular, the hypothalamus, all limbic structures, the deeper layers of the cerebral cortex, the striatum, the periaqueductal central grey and all levels of the major sensoty pathway are brain areas that are especially rich in somatostatin. Eighty percent of the somatostatin immunoreactivity in the hypothalamus is found in cells of the anterior periventricular nucleus (Fig. 1, [1]). The gut 5 cells of the mucosa and neurons, which are intrinsic to the submucous and... 

Somatostatin. Figure 1 Somatostatin-like im mu noreactivity in neurons of the periventricular hypothalamic nucleus of the rat. Coronal brain cryostat sections have been processed for im mu nohistochemistry and sequentially incubated with a primary monoclonal mouse anti human somatostatin antibody and secondary antimouse antibody conjugated with the fluorescence-dye Cy-3. Images have been taken with a Zeiss Axioplan fluorescence microscope. Scale bar, 100 pM. 

A12 Arcuate/periventricular Median Modulate hormone release... 

MS lesions or plaques can be identified grossly at autopsy (Fig. 38-1) and are sharply demarcated from the surrounding tissue. Plaques occur throughout the white matter, but areas of predilection such as the periventricular white matter are well known. Microscopic examination characteristically shows loss of myelin with preservation of axons (primary demyelination). However, although the most prominent pathology in MS is demye-lination, there are recent indications also for axonal and cortical pathology. Now techniques of confocal microscopy and immunocytochemistry have clearly demonstrated that transected axons are common in MS lesions [9],... 

Le WW, Bergohrn KA, Rassnick S, Hoffman GE (1999) Periventricular preoptic ara neurons coactivated with luteinizing hormone (LH)-releasing hormone (LHRH) neurons at the time of of the LH surge are LHRH afferents. Endocrinology 140 510-519... 

The intermediate length systems include the tuberoinfundibular system, which projects from the arcuate and periventricular nuclei into the intermediate lobe of the pituitary and the median eminence. This system is responsible for the regulation of such hormones as prolactin. The inter hypothalamic neurons send projections to the dorsal and posterior hypothalamus, the lateral septal nuclei and the medullary periventricular group, which are linked to the dorsal motor nucleus of the vagus such projections may play a role in the effects of dopamine on the autonomic nervous system. 

Whereas several peptides besides AVP are known to act synergistically with CRH, the only peptide candidate in humans that inhibits the HPA system at all regulatory levels of the system seems to be atrial natriuretic peptide (ANP). ANP has been shown to inhibit the stimulated release of CRH and ACTH in vitro and in vivo. This could be observed in humans as well, where ANP inhibits the CRH-induced ACTH (Keller et al. 1992), prolactin (Wiedemann et al. 1995), and cortisol secretion (StrOhle et al. 1998). ANP is not only synthesized by atrial myocytes (deBold et al. 1985) and released into the circulation, but is also found in neurons of different brain regions (Tanala et al. 1984) where specific receptors have been found. ANP receptors and immunoreactivity have been found in periventricular and paraventricular hypothalamic nuclei, the LC, and the central nucleus of the amygdala. 

Davis, E.C., Shryne, J.E., and Gorski, R.A. (1996) Structural sexual dimorphisms in the anteroventral periventricular nucleus of the rat hypothalamus are sensitive to gonadal steroids postnatally, but develop perlpubertally. Neuroendocrinology 63 142-148. 

In 1974, Liebeskind showed the existence of a central pain-suppressive system, and was able to produce analgesia by electrical stimulation of the periventricular gray matter within the brain. This electroanalgesia could be reversed by opiate antagonists, and showed a cross-tolerance with morphine-induced analgesia. These results indicated the existence of a neuronal system that uses an endogenous neuromodulator or neurotransmitter with opiate-like properties. 

Venero JL, Vizuete ML, Ilundain AA, Machado A, Echevarria M, Cano J. 1999. Detailed localization of aquaporin-4 messenger RNA in the CNS preferential expression in periventricular organs. Neuuoscience 94 239-250. 

WM lesions are rated separately in four WM areas periventricular, deep, watershed, and subcortical WM. By definition, periventricular WM foci have to be in contact with the ventricular wall, deep WM foci separated from the ventricles by a strip of normal-appearing WM and located outside watershed regions. Watershed regions are the areas located between the territories of two of the main cerebral arteries, like middle cerebral artery and anterior cerebral artery or middle cerebral artery and posterior cerebral artery. The subcortical... 

Fig. 9.6a-f. Periventricular white matter changes (FLAIR images), a Small caps around the frontal horns of lateral ventricles, b Large caps, c Extending caps, d Thin lining along the bodies of the lateral ventricles, e Smooth halo, f Irregular halo... 

Fig. 9.7a-f. White matter changes in regions other than the periventricular area (FLAIR images), a Multiple small focal lesions, b Multiple large focal lesions, c Multiple focal confluent lesions, d Diffusely confluent lesions irregular in shape. e,f Extensive... 

---