The force that pulls water into capillaries is called the

Osmotic pressure

The osmotic pressure is the force with which solute particles in blood (inside capillaries) pull on water.

Fluid movements across capillary wall is determined by two main factors;

Osmotic pressure depends on the number of osmotically active, non diffusible particles in the solutions separated by the membrane.

dopamine..

"it was found that some people who were taking the drug l-dopa to raise their levels of dopamine were developing schizophrenic-like symptoms supporting research a strength of the dopamine hypothesis is that there are many studies which have shown support for the neurochemical explanation."