Effect of acute restraint stress for 1 h on VP hnRNA levels in the PVN of naive rats (B) or 24 h after the last restraint in rats subjected to 1h repeated restraint for 14 days (D). Basal VP hnRNA levels were undetectable in the parvocellular region of naïve rats (A), while they were markedly elevated 24 hr after the last stress in repeatedly restrained rats (C). Darkfield photographs of emulsion dipped slides were taken through the medial parvocellular subdivision of the PVN (MP). 3rd V, Third ventricle; PM, posterior magnocellular; MP, medial parvocellular; RR × 14, repeated restraint, 1h daily for 14 days.