Lesions of the suprachiasmatic nuclei abolish the cervically stimulated prolactin surges in the rat

Cynthia Bethea, J. D. Neill

Research output: Contribution to journalArticle

48 Citations (Scopus)

Abstract

Stimulation of the uterine cervix in the rat induces a pattern of PRL secretion composed of two daily surges: a diurnal surge occurring as the lights go off and a nocturnal surge occurring as the lights go on. We recently demonstrated that these PRL surges are a true circadian rhythm in that they are entrained to an alternating photoperiod but free-run in constant dark. To determine if this induced rhythm is generated by the suprachiasmatic nuclei (SCN), as are the other endogenous rhythms, we examined the pattern of PRL secretion in rats which were first cervically stimulated and then lesioned in the SCN. The cervices of rats maintained in a 12-h light, 12-h dark photoperiod were stimulated electrically for 30 sec at 1900 h (day 0). The next day, cannulae were inserted in their carotid arteries, and radiofrequency lesions were made in the SCN. Blood samples for PRL analysis were obtained at 2-h intervals from 0900 h on day 3 to 1100 h on day 4. Sham-operated rats and rats in which the SCN were missed or incompletely lesioned exhibited the diurnal and nocturnal surges of PRL. However, the PRL surges were not present in rats in which the SCN were completely lesioned. These results suggest that the SCN are critical for generation of the PRL surges induced by cervical stimulation. Thus, PRL secretion after cervical stimulation is a circadian rhythm generated by the SCN and, as such, is analogous to other endogenous or spontaneous rhythms. It is unique in that it is not expressed until cervical stimulation is applied, and therefore, we postulate the participation of additional neural elements in this rhythm of hormone secretion.

Original languageEnglish (US)
Pages (from-to)1-5
Number of pages5
JournalEndocrinology
Volume107
Issue number1
StatePublished - 1980
Externally publishedYes

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Suprachiasmatic Nucleus
Prolactin
Photoperiod
Circadian Rhythm
Light
Cervix Uteri
Carotid Arteries
Hormones

ASJC Scopus subject areas

  • Endocrinology
  • Endocrinology, Diabetes and Metabolism

Cite this

Lesions of the suprachiasmatic nuclei abolish the cervically stimulated prolactin surges in the rat. / Bethea, Cynthia; Neill, J. D.

In: Endocrinology, Vol. 107, No. 1, 1980, p. 1-5.

Research output: Contribution to journalArticle

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