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Anterior pituitary hormone control by interleukin 2
1Department of Physiology, University of Texas Southwestern Medical Center, Dallas 75235-9040.
Summary
Interleukin 2 (IL-2), a lymphokine, directly influences anterior pituitary hormone release at femtomolar concentrations. This immune system messenger impacts prolactin, gonadotropins, ACTH, TSH, and growth hormone release, suggesting a paracrine role in pituitary function.
Area of Science:
- Immunology
- Endocrinology
- Neuroendocrinology
Background:
- Monokines modulate anterior pituitary hormone secretion.
- Interleukin 2 (IL-2) is a key lymphokine produced by T lymphocytes.
Purpose of the Study:
- To investigate the direct effects of IL-2 on anterior pituitary hormone release in vitro.
- To determine the minimal effective dose (MED) of IL-2 on various pituitary hormones.
Main Methods:
- Hemipituitaries were incubated with varying concentrations of IL-2 (10⁻¹⁷ to 10⁻⁹ M).
- Hormone release (PRL, LH, FSH, ACTH, GH, TSH) was measured via radioimmunoassay after IL-2 exposure and potassium-induced depolarization.
- Basal and stimulated hormone release were assessed at 1 and 2 hours.
Main Results:
- IL-2 stimulated basal prolactin (PRL) release but suppressed subsequent stimulated release (MED: 10⁻¹⁵ M).
- IL-2 suppressed basal and stimulated luteinizing hormone (LH) and follicle-stimulating hormone (FSH) release (MED: 10⁻¹⁶ M).
- IL-2 stimulated ACTH and TSH release (MEDs: 10⁻¹² M and 10⁻¹⁵ M, respectively) and suppressed basal growth hormone (GH) release (MED: 10⁻¹⁵ M).
Conclusions:
- IL-2 exerts direct, concentration-dependent effects on anterior pituitary hormone secretion.
- These findings suggest IL-2 acts as a paracrine messenger influencing pituitary function, potentially via lymphocytes within the gland or circulating IL-2.
- The reciprocal action on PRL and gonadotropins highlights IL-2's complex role in neuroendocrine regulation.