Pressor response to L-cysteine injected into the cisterna magna of conscious rats involves recruitment of hypothalamic vasopressinergic neurons.

The sulfur-containing non-essential amino acid L-cysteine injected into the cisterna magna of adult conscious rats produces an increase in blood pressure. The present study examined if the pressor response to L-cysteine is stereospecific and involves recruitment of hypothalamic vasopressinergic neurons and medullary noradrenergic A1 neurons. Intracisternally injected D-cysteine produced no cardiovascular changes, while L-cysteine produced hypertension and tachycardia in freely moving rats, indicating the stereospecific hemodynamic actions of L-cysteine via the brain. The double labeling immunohistochemistry combined with c-Fos detection as a marker of neuronal activation revealed significantly higher numbers of c-Fos-positive vasopressinergic neurons both in the supraoptic and paraventricular nuclei and tyrosine hydroxylase containing medullary A1 neurons, of L-cysteine-injected rats than those injected with D-cysteine as iso-osmotic control. The results indicate that the cardiovascular responses to intracisternal injection of L-cysteine in the conscious rat are stereospecific and include recruitment of hypothalamic vasopressinergic neurons both in the supraoptic and paraventricular nuclei, as well as of medullary A1 neurons. The findings may suggest a potential function of L-cysteine as an extracellular signal such as neuromodulators in central regulation of blood pressure.

Characteristics of cisternal cerebrospinal fluid associated with intracranial meningiomas in dogs: 56 cases (1985-2004).

OBJECTIVE: To determine CSF characteristics associated with intracranial meningiomas in dogs. DESIGN: Retrospective case series. ANIMALS: 56 dogs with intracranial meningiomas. PROCEDURES: Medical records of dogs with a histopathologic diagnosis of intracranial meningioma, in which CSF analysis had been performed, were reviewed. Information concerning total nucleated cell counts (TNCCs) and differential nucleated cell counts, RBC counts, and total protein concentration in CSF; seizure history and glucocorticoid administration; and location of meningiomas was recorded. RESULTS: TNCCs < 5 cells/microL were detected in 41 of 56 (73%) dogs; 5 of 56 (9%) dogs had TNCCs > 50 cells/microL. Analysis of CSF revealed predominantly neutrophilic pleocytosis in < 20% of dogs. There was a significant association between meningioma location (caudal portion of the cranial fossa or middle and rostral portion of the cranial fossae) and increased TNCCs (> or = 5 cells/microL). CONCLUSIONS AND CLINICAL RELEVANCE: Results were significantly different from those routinely reported in the veterinary literature. Neutrophilic pleocytosis, especially with TNCCs > 50 cells/microL, was not typical in CSF samples from dogs with intracranial meningiomas. Neutrophilic pleocytosis may not be detected in CSF samples from dogs with meningiomas located within the middle or rostral portion of the cranial fossae.

[Form and development of the human fetal subarachnoid cistern]. / Gestalt und Entwicklung der subarachnoidealen Zisternen beim menschlichen Feten

The development and form of the human fetal subarachnoid spaces have been elucidated by reconstruction (34 mm CRL fetus) and by plastic casts (several 20-30 cm CRL fetuses). Equivalents of adult cisterns are present in the young fetus. In older fetuses the cisternal shape is of adult type. It is suggested that pressure from the growing brain produces tension in the arachnoid mesenchyme and determines the initial orientation of the endo-ecto-meningeal limiting membrane. The fluid-filled subarachnoid spaces and the fetal brain together form a composite structural unit probably defining the configuration of the fetal head capsule. Prospective sutures develop over the inner ridges of the fetal dura. However, the lambda suture and the associated base of the tentorium eventually separate.