Young adult female rats were used as donors and recipients of homologous adenohypophyseal transplants. The transplants were stereotaxically placed unilaterally into the intact and 6-hydroxy-dopamine (6-OH-DA) denervated neostriatum. In the 6-OH-DA-denervated neostriatum the zone of prolactin-like immunoreactivity was increased in the neuropil surrounding the adenohypophyseal transplant compared with that in the non-denervated neostriatum. These results indicate that the loss of neostriatal dopamine leads to an increase in prolactin release from the adenohypophyseal striatal transplant giving further evidence for the existence of volume transmission in brain.