Brainstem prolactin mRNA is enhanced in mice with suppressed neuronal nitric oxide synthase activity
Lichao Chen1, Ping Taishi, Deborah Duricka
1Department of Veterinary and Comparative Anatomy, Pharmacology, and Physiology, Washington State University, 205 Wegner Hall, P.O. Box 646520, Pullman, WA 99164-6520, USA.
Abstract:
Prolactin (PRL) and vasoactive intestinal polypeptide (VIP) mRNA levels were elevated in the brainstem of neuronal nitric oxide synthase (nNOS) gene knockout (KO) mice compared to the levels in nNOS control mice. In addition, PRL mRNA levels increased in the hypothalamus and the brainstem of nNOS control mice after administration of 7-nitro-indazole (7-NI), a relatively selective nNOS inhibitor. The results suggest that NO inhibits PRL. No differences in the genes measured were observed in inducible NOS KO mice.
Insights
Nitric oxide (NO) inhibits prolactin (PRL) release. Studies in neuronal nitric oxide synthase (nNOS) gene knockout mice showed elevated PRL and vasoactive intestinal polypeptide (VIP) mRNA levels, supporting this NO-PRL inhibition.
Area of Science:
- Neuroendocrinology
- Molecular Biology
- Nitric Oxide Signaling
Background:
- Neuronal nitric oxide synthase (nNOS) plays a role in regulating various physiological processes.
- The relationship between nitric oxide (NO) and prolactin (PRL) secretion is not fully understood.
- Vasoactive intestinal polypeptide (VIP) is a neuropeptide with diverse functions, including potential roles in hormone regulation.
Purpose of the Study:
- To investigate the role of nNOS in the regulation of PRL and VIP mRNA levels in the brain.
- To determine if NO directly inhibits PRL expression or release.
Main Methods:
- Utilized nNOS gene knockout (KO) mice and their wild-type controls.
- Administered 7-nitro-indazole (7-NI), a selective nNOS inhibitor, to control mice.
- Quantified mRNA levels of PRL and VIP in specific brain regions (hypothalamus, brainstem) using molecular techniques.
Main Results:
- Elevated PRL and VIP mRNA levels were observed in the brainstem of nNOS KO mice compared to controls.
- Administration of 7-NI led to increased PRL mRNA levels in the hypothalamus and brainstem of control mice.
- No significant changes in measured gene levels were found in inducible NOS (iNOS) KO mice.
Conclusions:
- The findings suggest that NO, likely through nNOS, exerts an inhibitory effect on PRL expression.
- nNOS activity is implicated in the regulation of both PRL and VIP mRNA levels in the brain.
- These results contribute to understanding the complex neuroendocrine regulation of prolactin.
