How might behaviors affect hormones? The birdsong example demonstrates how hormones can affect behavior, but as noted, the reciprocal relation also occurs; that is, behavior can affect hormone concentrations. For example, the sight of a territorial intruder may elevate blood testosterone concentrations in resident male birds and thereby stimulate singing or fighting behavior. Similarly, male mice or rhesus monkeys that lose a fight decrease circulating testosterone concentrations for several days or even weeks afterward. Comparable results have also been reported in humans. Testosterone concentrations are affected not only in humans involved in physical combat, but also in those involved in simulated battles. For example, testosterone concentrations were elevated in winners and reduced in losers of regional chess tournaments.
The regulatory domains of cPKC isoforms (cPKCα: cPKC-alpha; cPKCβI: cPKC-beta I, cPKCβII: cPKC-beta II; and cPKCγ: cPKC-gamma) contain a C1 domain consisting of tandem ~50 amino acid long sequences termed C1A and C1B. The C1A and C1B subdomains each have six cysteines and two histidines that coordinate two Zn 2+ ions. The cPKCβII enzyme is an alternatively spliced version of cPKCβI. The C1A/C1B motifs function as a DAG-/PMA-binding motif (PMA: phorbol myristic acid). The regulatory domains of the cPKC isoforms also contain a C2 domain that binds anionic phospholipids in a calcium-dependent manner. All the cPKC isoforms require DAG, Ca 2+ , and phospholipids for activation.