Blood was collected at 20-second intervals from the external carotid artery and from the dorsal longitudinal sagittal sinus (sagittal sinus, SS) of ovariectomized sheep. The point of SS catheterization was very near the point at which diencephalic effluent entered the SS. Concentrations of beta-endorphin (β-EP) immunoreactivity were quantified by radioimmunoassay procedures in blood plasma and in cerebrospinal fluid (CSF) from the cisterna magna. Increases in plasma β-EP concentration were provoked by intracarotid injection of naloxone and by experimental production of bacteremia (i.e., intravascular bacteria), but these procedures failed to increase β-EP in CSF. Quantities of β-EP in plasma samples from the SS were assumed to represent arterial contribution (minus tissue uptake), diencephalic secretion, and retrograde delivery of pituitary β-EP to the diencephalic effluent. The arterial contribution was removed mathematically by subtracting the arterial plasma β-EP concentration from the concurrent SS plasma concentration of β-EP to yield a paired arteriovenous (AV) difference. When this AV difference was consistently positive and satisfied our statistical criterion for being greater than zero, we concluded that either pituitary β-EP was delivered in a retrograde manner to diencephalon or the diencephalon secreted β-EP. However, this situation occurred in only 5 of 31 periods examined. Furthermore, only 2 of these 5 periods occurred during times of increasing arterial concentrations of β-EP. Such concurrence would be expected if both changes were caused by a major discharge of β-EP from the pituitary gland. Therefore, the present results provide little evidence for retrograde delivery of pituitary β-EP to the brain without systemic dilution.

Keywords:
Beta-endorphin, Retrograde flow, Pituitary effluent, Arteriovenous differences, Sheep
This content is only available via PDF.
© 1985 S. Karger AG, Basel
1985
Copyright / Drug Dosage / Disclaimer
Copyright: All rights reserved. No part of this publication may be translated into other languages, reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying, recording, microcopying, or by any information storage and retrieval system, without permission in writing from the publisher.
Drug Dosage: The authors and the publisher have exerted every effort to ensure that drug selection and dosage set forth in this text are in accord with current recommendations and practice at the time of publication. However, in view of ongoing research, changes in government regulations, and the constant flow of information relating to drug therapy and drug reactions, the reader is urged to check the package insert for each drug for any changes in indications and dosage and for added warnings and precautions. This is particularly important when the recommended agent is a new and/or infrequently employed drug.
Disclaimer: The statements, opinions and data contained in this publication are solely those of the individual authors and contributors and not of the publishers and the editor(s). The appearance of advertisements or/and product references in the publication is not a warranty, endorsement, or approval of the products or services advertised or of their effectiveness, quality or safety. The publisher and the editor(s) disclaim responsibility for any injury to persons or property resulting from any ideas, methods, instructions or products referred to in the content or advertisements.
You do not currently have access to this content.