This study examines the expression of pituitary adenylate cyclase activating polypeptide (PACAP) mRNA in the rat spinal cord during normal conditions and in response to sciatic nerve transection. Previously, PACAP immunoreactivity has been found in fibers in the spinal cord dorsal horn and around the central canal and in neurons in the intermediolateral column (IML). Furthermore, in the dorsal root ganglia, PACAP immunoreactivity and PACAP mRNA expression have been observed preferentially in nerve cell bodies of smaller diameter terminating in the superficial laminae of the dorsal horn. However, neuronal expression of PACAP mRNA in adult rat spinal cord appeared limited to neurons of the IML. By using a refined in situ hybridization protocol, we now detect PACAP mRNA expression in neurons primarily in laminae I and II, but also in deeper laminae of the spinal cord dorsal horn and around the central canal. In addition, PACAP mRNA expression is observed in a few neurons in the ventral horn. PACAP expression in the ventral horn is increased in a population of large neurons, most likely motor neurons, both after distal and proximal sciatic nerve transection. The proposed role of PACAP in nociception is strengthened by our findings of PACAP mRNA-expressing neurons in the superficial laminae of the dorsal horn. Furthermore, increased expression of PACAP in ventral horn neurons, in response to nerve transection, suggests a role for PACAP in repair/regeneration of motor neurons.

Micromolar concentrations of the biologically active oestrogen 17β-oestradiol reduce agonist-induced force in vascular preparations through an unidentified mechanism. The aim of the present study was to investigate the importance of oestrogen receptor β (ERβ) for oestrogen-induced vascular relaxation. 17β-oestradiol was added to aortic rings from ERβ knock-out (-/-) and wild-type (+/+) mice precontracted with noradrenaline. 17β-oestradiol caused a concentrationdependent (1-100 µM) relaxation of aortic rings from both -/-and +/+ animals of both sexes. Rings from male and female -/-mice were more sensitive to 17β-oestradiol than those from +/+ mice. Medial thickness, determined by computerized image analysis, was similar in rings from -/-and +/+ animals. Endothelium, as determined by immuno-cytochemistry, was present in -/-and +/+ aorta. Maximal noradrenaline evoked force and sensitivity to noradrenaline were similar in both groups. In summary ERβ modulates vascular relaxation to µM concentrations of oestrogen; lack of ERβ renders the vascular wall supersensitive to 17β-oestradiol. Lack of ERβ caused no change in vascular wall morphology suggesting that this ER subtype is not involved in vascular structure development.