Maitotoxin stimulates steroid and peptide hormone secretion by swine luteal tissue

Johannes D Veldhuis, K. Yoshida, W. DuBois, M. J. Fields

Research output: Contribution to journalArticle

7 Citations (Scopus)

Abstract

The impact of calcium influx on the secretion of steroidal and nonsteroidal ovarian products was tested using a novel marine toxin, maitotoxin, a putative activator of endogenous calcium channels. In incubations of swine luteal minces in balanced salt solution, maitotoxin induced dose-dependent (3-12.5 ng/ml) and time-dependent (15-60 min) secretion of progesterone and relaxin. The magnitude of these stimulatory effects approached that observed for luteinizing hormone (LH) and was explicitly dependent on the presence of extracellular calcium ions. Maitotoxin's actions were not significantly impeded by substitution of choline for sodium ions in the incubation medium. Moreover, measurements of tissue calcium content by atomic absorption spectrometry indicated that maitotoxin augmented the total cellular content of calcium by 44 ± 3.1% within 1 min. This time course was distinct from that observed for LH. The specificity of these actions on the calcium pathway was further suggested by the absence of any measurable effects of maitotoxin on luteal cAMP generation. We conclude that maitotoxin transiently increases luteal calcium content without altering cAMP generation and elicits concomitant release of both a steroidal (progesterone) and nonsteroidal (relaxin) product of the corpus luteum. Such actions are dependent on extracellular calcium but not sodium ions. These observations provide evidence for a calcium-dependent stimulatory pathway that activates both steroidal and nonsteroidal mechanisms of secretion in the swine corpus luteum.

Original languageEnglish (US)
JournalAmerican Journal of Physiology - Endocrinology and Metabolism
Volume252
Issue number1
StatePublished - 1987
Externally publishedYes

Fingerprint

Steroid hormones
Peptide Hormones
Corpus Luteum
Swine
Steroids
Tissue
Calcium
Relaxin
Ions
Luteinizing Hormone
Progesterone
Marine Toxins
Calcium Channel Agonists
Sodium
Atomic absorption spectrometry
maitotoxin
Calcium Channels
Choline
Spectrum Analysis
Substitution reactions

ASJC Scopus subject areas

  • Biochemistry
  • Endocrinology
  • Physiology

Cite this

Maitotoxin stimulates steroid and peptide hormone secretion by swine luteal tissue. / Veldhuis, Johannes D; Yoshida, K.; DuBois, W.; Fields, M. J.

In: American Journal of Physiology - Endocrinology and Metabolism, Vol. 252, No. 1, 1987.

Research output: Contribution to journalArticle

Veldhuis, Johannes D ; Yoshida, K. ; DuBois, W. ; Fields, M. J. / Maitotoxin stimulates steroid and peptide hormone secretion by swine luteal tissue. In: American Journal of Physiology - Endocrinology and Metabolism. 1987 ; Vol. 252, No. 1.
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