Lack of behavioural effects following intraventricular infusion of somatostatin in the conscious goat

The epidural and intrathecal administration of somatotrophin-release inhibiting factor: native and synthetic analogues

It is well-known that morphine is the king of analgesics. It is widely used, and administered in various ways for the control of acute and chronic pain states. There are, however, certain types of pain and certain clinical conditions in which morphine cannot be used due to the risk of possible complications. These are usually pain states associated with intracranial hypertension, the presence of serious respiratory problems, the onset of major opioid tolerance, persistent vomiting, and so on. The search for "alternative analgesics" has been in progress for a decade, alternatives that could be used alone or in combination for spinal administration in the treatment of complex chronic pain states and with a low incidence of secondary effects. Today, research is carefully assessing the clinical effectiveness and the side effects of a series of drugs for spinal administration, that is, epidural or intrathecal, such as the new narcotics, alpha-2 agonists, central muscle relaxants, calcitonin, and local anesthetics. In this alternative analgesic category we have to mention the somatotrophin-release inhibiting factor (SRIF), which is an ubiquitous native hormone with widespread, predominantly inhibitory actions, and octreotide, its synthetic analogue. In this article we review the literature on the natural drug and its synthetic analogue, paying particular attention to the problems connected with intraspinal administration and analgesic properties.

Intrathecal somatostatin in the guinea pig: effects on spinal cord blood flow, histopathology and motor function

In the present investigation, the vasoconstrictive, motor and neurodegenerative effects of intrathecal somatostatin (SST) were assessed in guinea pigs implanted with lumbar intrathecal catheters. Five consecutive dose increments of SST (5, 10, 15, 30 and 60 micrograms) to a total of 120 micrograms during the period of 16 +/- 3 min, resulted in a moderate (< 20%), gradual decrease of the spinal blood flow monitored with the laser-doppler method. A subsequent injection of clonidine (50 micrograms) or norepinephrine (10 micrograms) resulted in a more pronounced decrease of spinal blood flow (35% and 79%, respectively). Three consecutive, daily intrathecal injections of 30 or 60 micrograms SST did not cause any loss of weight support or paralysis of the hind limbs. There were no histopathological changes in the white or gray matter of the thoracic and lumbar sections of the spinal cords. It is concluded that SST, in the doses studied, is not neurodegenerative in guinea pigs. These findings are in contrast to those previously seen in rats. The implication of this study may be the necessity to use several alternate animal species in order to evaluate the antinociceptive and neurodegenerative properties of the peptides administered by the intrathecal route and the choice of dose to be compared across species.