Effects of Spreading Depression on Stress-Induced Changes in Plasma Prolactin and LH 1

Abstract

Summary

Female rats rendered “pseudo-pregnant” by treatment with PMS and hCG and ovariectomized rats injected with estradiol and progesterone (OVX-E₂-P) were subjected to cortical spreading depression (SD). Within 7-10 min under ether anesthesia in a stereotaxic instrument a frontal craniotomy was performed and a cotton ball saturated with physiological saline (control) or 25% KC1 was applied to the exposed dura, covered with dental cement and skin sutured. The animals were then placed in separate containers in an isolated room and decapitated for collection of trunk blood at 0, 15, 30, or 60 min after surgery. In PMS-hCG saline-treated control animals, prolactin levels had dropped by 15 and 30 min when compared with the zero-time values but by 60 min had increased significantly above the 30-min level. At that time (60 min), prolactin values in the KC1 group were significantly lower than in the controls. Corticosterone levels were high at both 15 and 60 min in control and KC1 groups. In OVX-E₂-P control animals, plasma prolactin levels also rose at 60 min compared with 15- and 30-min samples and at 60 min were significantly higher than in the KC1 group. In control animals, LH levels were lower at 15 and 60 min than at zero time, but they remained unchanged in the KC1 group. The data are interpreted as indicating that cortical SD suppresses the stress responses observed in saline-treated control animals.

The authors thank Ms. Katherine Bangs, Ms. Frances Smith and Ms. Lois Fels for valuable technical and secretarial assistance and Mr. Bob McAllister for drawing the figures.