Fabbri A, Fraioli F, Pert C B, Pert A
Brain Res. 1985 Sep 23;343(2):205-15. doi: 10.1016/0006-8993(85)90736-x.
Autoradiographic analyses of salmon calcitonin (sCT) binding in the rat mesencephalon revealed an exceptionally high concentration of receptors in the ventral and ventrolateral segments of the periaqueductal gray matter (PAG) extending along the entire rostral-caudal axis. Relatively heavy labeling was also seen along a band extending ventrolaterally through the mesencephalic reticular formation. Other receptor-rich areas include the nucleus linearis, pars compacta and lateralis of the substantia nigra, locus coeruleus, parabrachial nuclei and nucleus raphe pontis of the pontine reticular formation. Injections of sCT into the PAG induced a dose-dependent increase in hot-plate latencies. All rostral-caudal levels of these brain regions appeared to be equally responsive. Injections into the midline pontine reticular formation were also effective in increasing response latencies. Unilateral injections into the hypothalamus, medial thalamus, ventral thalamus and mesencephalic reticular formation proved to be ineffective. Human calcitonin (hCT) was considerably less potent. These biological effects are consistent with the potencies of both peptides in displacing 125I-sCT from slide-mounted sections of rat PAG. Naloxone failed to antagonize sCT-induced analgesia, suggesting an opiate independent mechanism for this peptide in eliciting analgesia.
对大鼠中脑鲑鱼降钙素（sCT）结合的放射自显影分析显示，导水管周围灰质（PAG）腹侧和腹外侧段沿整个头尾轴存在异常高浓度的受体。在一条从腹外侧穿过中脑网状结构的带中也观察到相对较重的标记。其他富含受体的区域包括中缝核、黑质致密部和外侧部、蓝斑核、臂旁核以及脑桥网状结构的脑桥中缝核。向PAG注射sCT可使热板潜伏期呈剂量依赖性增加。这些脑区的所有头尾水平似乎都有同等反应。向脑桥中线网状结构注射也能有效增加反应潜伏期。向丘脑下部、内侧丘脑、腹侧丘脑和中脑网状结构单侧注射被证明无效。人降钙素（hCT）的效力要低得多。这些生物学效应与两种肽从大鼠PAG载玻片切片上置换125I-sCT的效力一致。纳洛酮未能拮抗sCT诱导的镇痛作用，提示该肽产生镇痛作用的机制与阿片类无关。
