Skip Navigation

This Article
Right arrow Full Text (PDF )
Right arrow Submit a response
Right arrow Alert me when this article is cited
Right arrow Alert me when eLetters are posted
Right arrow Alert me if a correction is posted
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Alert me to new issues of the journal
Right arrow Add to My Personal Archive
Right arrow Download to citation manager
Right arrowRequest Permissions
Google Scholar
Right arrow Articles by O'Byrne, K.T.
Right arrow Articles by Knobill, E.
Right arrow Search for Related Content
PubMed
Right arrow Articles by O'Byrne, K.T.
Right arrow Articles by Knobill, E.
Social Bookmarking
Add to CiteULike   Add to Connotea   Add to Del.icio.us  
What's this?

Human Reproduction, Vol. 8, No. suppl_2, pp. 37-40, 1993
© 1993 European Society of Human Reproduction and Embryology

Electrophysiological approaches to gonadotrophin releasing hormone pulse generator activity in the rhesus monkey

K.T. O'Byrne and E. Knobill1

Laboratory for Neuroendocrinology, The University of Texas Medical School P.O. Box 20708, Houston, TX 77225, USA

Correspondence: 1To whom correspondence should be addressed

Precipitous increases in multi-unit electrical activity (MUA volleys) can be recorded from the mediobasal hypothalamus of the rhesus monkey that are invariably synchronous with the initiation of luteinizing hormone (LH) pulses and thus serve as markers of gonadotrophin releasing hormone (GnRH) pulse generator activity. Continuous radiotelemetric monitoring of this activity throughout the menstrual cycle confirmed a lower pulse generator frequency during the luteal phase than in the follicular phase. Unexpectedly, however, just before the initiation of the LH surge an abrupt reduction in frequency was observed, followed, on occasion, by a total arrest of GnRH pulse generator activity for a day or two. This monitoring technique also revealed a reduction of pulse generator frequency at night. This appeared to be an acute phenomenon observable in the first MUA volleys after the lights are turned off, as is the increase in frequency when the lights are turned on in the morning suggesting a direct action of light, a conclusion that was verified using lighting periods other than the customary ones. This action of light, however, is superimposed upon a diurnal rhythm, as shown by a reduction in pulse generator frequency during the subjective night when the monkeys are kept in constant light or darkness. The duration of the MUA volley in the intact monkey is 1–3 min, compared with some 20 min in the ovariectomized female. While oestradiol reduces the volley duration in the ovariectomized female to that of intact monkeys within 6 h, it takes some 6 weeks following ovariectomy for the duration characteristic of castrates to be re-established. Utilization of a spike analysis programme revealed that the MUA volleys that reflect the activity of the GnRH pulse generator represent the synchronous increase in firing rate of single units and the simultaneous decrease in the firing rate of a smaller population of others.

Key words: diurnal rhythms/electrophysiology/GnRH pulse generator/ovariectomy/rhesus monkey


Add to CiteULike CiteULike   Add to Connotea Connotea   Add to Del.icio.us Del.icio.us    What's this?


This article has been cited by other articles:


Home page
 Toxicol PatholHome page
G. F. Weinbauer, M. Niehoff, M. Niehaus, S. Srivastav, A. Fuchs, E. Van Esch, and J. M. Cline
Physiology and Endocrinology of the Ovarian Cycle in Macaques
Toxicol Pathol, December 1, 2008; 36(7_suppl): 7S - 23S.
[Abstract] [Full Text] [PDF]


Disclaimer: Please note that abstracts for content published before 1996 were created through digital scanning and may therefore not exactly replicate the text of the original print issues. All efforts have been made to ensure accuracy, but the Publisher will not be held responsible for any remaining inaccuracies. If you require any further clarification, please contact our Customer Services Department.