#
Rhythms in the Hypothalamus and Pituitary

August 4 to August 8, 2008
at the

American Institute of Mathematics,
Palo Alto, California

organized by

Richard Bertram,
Yue-Xian Li,
David McCobb,
Arthur Sherman,
and Mary Lou Zeeman

## Original Announcement

This workshop will bring together
experimental and mathematical researchers in neuroendocrinology to
study and develop mathematical models for rhythmogenic mechanisms in
the hypothalamus and pituitary.
Endocrine hormone levels in the blood exhibit a wide variety of rhythms with periods ranging from minutes to a year. In several cases, rhythmicity of a hormonal signal has been shown to be vital for activating the target cells. For example, periodic release of hypothalamic GnRH is necessary for initiating and maintaining reproductive function in mammals. The hypothalamus appears to be the center of origin of many hormonal rhythms, where endocrine neurons synchronize to release periodic signals. However, pituitary responses to hypothalamic stimuli can be counter-intuitive, depending in part on feedback from target tissues. Despite the significance of the rhythms for hormonal actions under both normal
and pathological conditions, we do not yet understand the mechanisms
underlying these rhythms and their interactions. Rhythmogenesis in
excitable endocrine cells is a complex process that involves sophisticated
feedback-feedforward interactions, membrane electrical activity, calcium
signaling and network synchronization. Mathematical models are needed to
integrate data and clarify rhythmogenic mechanisms in the hypothalamus
and pituitary.

Specific topics include:

- The mechanism of GnRH pulse generation and mathematical models for the synchronization of GnRH neurons.
- The development of a model of the menstrual/estrus cycle that incorporates the interactions between GnRH
neurons, pituitary gonadotrophs and the ovaries.
- The development of mathematical models for other hormonal rhythms, interations, and responses to
non-rhythmic factors, as in the stress axis.
- Mechanisms for the electrical activities and calcium dynamics of hypothalamic neurons and pituitary cells
and mathematical models of these activities.
- The relationship between membrane electrical activity and hormonal rhythms: experimental evidence and
mathematical models.

## Material from the workshop

A list of participants.
The workshop schedule.

A report on the workshop activities.