Angiotensin II Receptor Content Within the Circumventricular Organs Increases After Experimental Hydrocephalus in Rats

Abstract

Hydrocephalus is known to cause various endocrinological abnormalities. These abnormalities are either though a direct effect on anterior hypothalamus or pituitary gland. However almost nothing is known about the effects of hydrocephalus on the intrinsic angiotensin system of the brain. The aim of this study is to investigate the effect of hydrocephalus on neurotransmitter-rich circumventricular organ systems. Such an effect was investigated by means of angiotensin receptor content in subfornical organ (SFO), organum vasculosum lamina terminalis (OVLT), area postrema (AP) and the median eminence (ME). Experimental hydrocephalus was created in rats by the intracisternal kaolin injection method as described by Shapiro et al. The receptor content was measured at 4-6 weeks by in-vitro autoradiography method as described by Israel et al. Angiotensin II receptor content in hydrocephalic animals was found to be statistically increased in SFO, OVLT and ME but not in AP when compared with the normal animals. Receptor content was found to have increased by 182.4% at SFO, 76.7% at ME, 7.7% at AP and 22.1% at OVLT after kaolin injection. These findings may indicate the possible role of CVO's on pathological conditions such as hydrocephalus.

Neonatal Brain Hemorrhage (NBH) of Prematurity: Translational Mechanisms of the Vascular-Neural Network

“…Experimentally, angiotensin II receptor content is increased in third ventricle circumventricular organ systems [289], while alterations in the catecholaminergic system have been described [269, 290]. The exact pathogenesis in HPA dysfunction has not been clearly demonstrated, but it potentially parallels gross and cellular mechanisms evident in periventricular white matter disease.…”

Does Ventriculoperitoneal Shunting Improve Thyroid Hormone Levels in Hydrocephalic Newborns?

“…Neuropeptide Y, somatostatin, and corticotropin-releasing factor are neuropeptides involved in cognitive functions. It was reported that concentrations of neuropeptide Y and somatostatin were decreased in patients with normal pressure hydrocephalus, and that levels of these neuropeptides after shunt surgery were normal [16]. Improvements in cognitive function observed after shunt insertion were considered to be associated with normalization of the levels of these neuropeptides [16].…”

“…It was reported that concentrations of neuropeptide Y and somatostatin were decreased in patients with normal pressure hydrocephalus, and that levels of these neuropeptides after shunt surgery were normal [16]. Improvements in cognitive function observed after shunt insertion were considered to be associated with normalization of the levels of these neuropeptides [16]. Because assessment of cognitive functions in newborns was not possible, these studies in adults may provide insight regarding the pathological effect of hydrocephalus at cellular, anatomical, and biochemical levels.…”