# CONTROL OF PROLACTIN SECRETION

> **NIH NIH R01** · FLORIDA STATE UNIVERSITY · 1994 · $147,133

## Abstract

Prolactin is a hormone secreted from cells of the anterior pituitary gland
which may serve many roles in addition to that implied by its name. That
is, other than promoting lactation in all mammals, prolactin has been
shown to play a role in maintenance of progesterone secretion (and hence
pregnancy) by the ovaries, as well as the immune response and
osmoregulation in many mammals. Other than the classic nursing-induced
release of prolactin secretion described in all mammals, a host of other
stimuli such as stress and ovarian steroids also induce prolactin
secretion. We have shown that the mating stimulus leads to 10 days of
daily nocturnal and diurnal surges of prolactin secretion from the
pituitary gland. This hormone is responsible for maintenance of the corpus
luteum. During the 14 years we have had this grant we have described the
neural circuitry as well as the role of the ovaries and uterus responsible
for initiating and maintaining the surges of prolactin. During the
previous granting period we have discovered why the rat has 2 surges of
prolactin in response to the mating stimulus. We have found that there is
an endogenous stimulatory rhythm originating in the hypothalamus and that
the prolactin-releasing expression of this rhythm is masked by dopamine
acting at the pituitary. The rhythm is unmasked by any dopamine-lowering
stimulus such as mating. Using pharmacologic approaches and direct
measurement we have identified OT as the neurohormone controlling the
nocturnal and diurnal component of the rhythm and VIP as the
neuromodulator controlling the nocturnal component while 5-HT controls the
diurnal component. The specific aims of the present application are: (1)
to characterize the anatomical and physiological relationship between the
neuromodulators and neurohormones controlling the endogenous stimulatory
rhythm and (2) to characterize the cellular mechanisms through which the
lactotroph transduces the twice daily signal into prolactin secretion.
These studies are important because they will identify the controls of
prolactin secretion from the whole animal to the cellular level which are
operative in not only mating but also other physiological states such as
lactation. We provide evidence that the control of this endogenous
stimulatory rhythm for prolactin secretion may be operative and
generalizable to control of prolactin secretion in a host of other
physiological states.

## Key facts

- **NIH application ID:** 2196830
- **Project number:** 2R01HD011669-15A1
- **Recipient organization:** FLORIDA STATE UNIVERSITY
- **SAM.gov UEI:** JF2BLNN4PJC3
- **Principal Investigator:** Marc R Freeman
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 1994
- **Award amount:** $147,133
- **Award type:** 2
- **Project period:** 1978-04-01 → 1997-11-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/2196830

## Citation

> US National Institutes of Health, RePORTER application 2196830, CONTROL OF PROLACTIN SECRETION (2R01HD011669-15A1). Retrieved via MORVS 2026-10-25 from https://api.morvs.ai/grant/nih/2196830. Licensed CC0.

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