= Iain J. Clarke
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<Iain J. Clarke> is a physiologist whose work investigates how brain signals regulate reproduction and other body functions. His Monash profile identifies research in reproduction, the <hypothalamus> and large-animal models.<Iain Clarke profile by Monash University>[research keywords and personal profile]{ref}
With <James T. Cummins>, he developed experiments that directly compared hormone signals and pituitary responses. After the portal-sampling work, a 1985 study used ewes whose pituitaries had been surgically disconnected from hypothalamic input. The investigators supplied controlled <GnRH> pulses and measured <LH> responses. Animals receiving a fixed-size pulse every two hours had larger individual LH responses than animals receiving it hourly; a later infusion tested the releasable pituitary hormone pool.<GnRH pulse frequency determines LH pulse amplitude by altering the amount of releasable LH in the pituitary glands of ewes by Iain J. Clarke and James T. Cummins>[Summary, surgical isolation, pulse schedules and subsequent infusion]{ref}
The design makes timing an explicit experimental variable. With $250\,\mathrm{ng}$ per pulse, an hourly schedule delivers $6\,\mathrm{\mu g}$ per day, while a two-hour schedule delivers $3\,\mathrm{\mu g}$. Thus changing frequency at fixed pulse size also changes total input; that distinction belongs in the interpretation. The resulting work connects a hormone's temporal pattern with the response and storage capacity of its target organ.
\Image[https://research.monash.edu/files-asset/248355252/profile%2Bphoto?f=jpg&w=160]
{title=Iain J. Clarke, identified portrait on his Monash University profile}
{description=External image from <Iain Clarke profile by Monash University>.}
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