Neuregulin-β isoforms associated with neuronal processes

1. A method of screening for agents that increase or decrease the expression level of a neuregulin-β isoform, comprising the steps of:

a) administering said biological agent to a test mammal,

b) subjecting said test mammal and a control mammal to a maze test, wherein said control mammal has not been administered said biological agent,

c) determining an expression pattern of a neuregulin-β isoform which has an isoelectric point (pl) in the range from pH 4.3 to 5.0, wherein said neuregulin-β isoform has an apparent molecular mass of about 32 kd as determined using 2 dimensional electrophoresis and mass spectrometry, of said test mammal and said control mammal,

d) comparing said expression pattern of said test mammal and said control mammal to determine if the two expression levels are the same, or if said biological agent increased or decreased the expression levels of said neuregulin-β isoform, wherein an increase or decrease in the expression level of said neuregulin-β isoform in said test mammal's hippocampal tissue indicates that said biological agent increased or decreased the expression level of said neuregulin-β isoform,

wherein said test mammal is a rat.

2. The method of claim 1 , wherein the step of determining an expression pattern comprises 2-dimensional electrophoresis, wherein a first dimension is isoelectric focusing.