The amino-terminal heptapeptide of the algesic substance P provides analgesic effect in relieving chronic neuropathic pain.

Of painful conditions, somatic pain of acute nociceptive origin can be effectively managed clinically, while neuropathic pain of chronic neuropathy origin is difficult to control. For molecules involved in pain sensation, substance P (SP) is algesic, exacerbating painful sensation, while its amino-terminal fragment, heptapeptide SP, confers biological activities different from its full-length parent neuropeptide precursor. We previously demonstrated SP interaction with pain processing to alleviate chronic pain.

Distribution of [3H]-corticosterone in urine, feces and blood of male Sprague-Dawley rats after tail vein and jugular vein injections.

The present study aimed to investigate the time-course and distribution of [(3)H]-corticosterone in urine, feces and blood of male Sprague-Dawley rats after intravenous administration of a low dose (1 microCi), and to investigate whether different intravenous routes of administration may affect the dynamics of excreted [(3)H]-corticosterone in the feces. One microCi [(3)H]-corticosterone was injected intravenously either through the tail vein in manually restrained rats or through a jugular vein catheter three days after surgical implantation. Urine and feces were collected at different time points over 78 h from the rats injected in the tail vein, and blood and feces were collected over 48 h from rats injected in the jugular vein.