Non-endocrine applications of somatostatin and octreotide acetate: facts and flights of fancy

Somatostatin receptors are strongly expressed in palmoplantar sweat glands and ducts: studies of normal and palmoplantar pustulosis skin

BACKGROUND

The acrosyringium is the target for inflammation in the chronic and intensely inflammatory skin disease palmoplantar pustulosis (PPP). The sweat-gland apparatus seems to be an immunocompetent structure that probably contributes to skin defence. Furthermore, the sweat gland and duct may be a hitherto unrecognized neuroendocrine organ.

AIM

To obtain further information about the neuroendocrine properties of the sweat-gland apparatus by examining expression of the somatostatin receptors (SSTRs) 1-5 in healthy palmar skin and in PPP skin.

METHODS

Biopsy specimens were taken from 25 patients with PPP and 25 healthy controls. Immunohistochemical analysis was used to investigate expression of SSTRs 1-5.

RESULTS

SSTRs 1-5 were expressed in both epidermal and endothelial structures. The staining intensity of the sweat-gland apparatus was more pronounced than that of the epidermis. Expression differed significantly between lesional PPP and normal plantar skin, with increased expression of SSTRs 3 and 4 in ducts in epidermis, and decreased expression of SSTR 1 in ducts in both papillary and reticular dermis. In specimens with pronounced inflammation, numerous dendritic cells with strong expression of SSTRs 1, 2 and 4 were seen, especially in the papillary dermis.

CONCLUSIONS

The presence of SSTRs in palmoplantar skin, and specifically at high density in the sweat glands and ducts, might be of particular importance in skin neuroimmunoendocrinology. Although the relevance of the changes in SSTR expression in PPP skin compared with normal skin is unclear, our hypothesis is that these differences might influence the function of both the neuroendocrine and neuroimmunological properties of palmoplantar skin, especially in the sweat-gland apparatus.

The effect of hyperbaric oxygen therapy on the adverse effects of octreotide on wound healing

OBJECTIVE

Octreotide, a long-acting somatostatin analogue, has been used in the treatment of various disorders. Octreotide has significant detrimental impacts upon wound healing. We tested the hypothesis that hyperbaric oxygen therapy may overcome octreotide-mediated suppression of wound healing.

DESIGN

Prospective, randomised, parallel-group animal study.

METHODS

Operated rats were divided into four groups: (1) controls, (2) octreotide therapy, (3) hyperbaric oxygen therapy and (4) combination of octreotide and hyperbaric oxygen therapy. Wound healing was assessed by breaking-strength measurements, hydroxyproline levels and fibrosis scores.

RESULTS

Octreotide decreased the breaking-strength measurements, hydroxyproline levels and fibrosis scores to 72%, 88% and 55%, respectively, of the control group. In the combination group, hyperbaric oxygen therapy increased breaking-strength measurements and hydroxyproline levels to 137% and 126%, respectively, of the control group. In the combination group, hyperbaric oxygen therapy tended to increase the fibrosis scores to 111% of the control group, but without statistical significance.

CONCLUSION

Hyperbaric oxygen therapy tends to reverse the octreotide-induced impairment of wound healing.

Strategies to antagonise the cyclosporine A-induced proliferation of human pulmonary artery smooth muscle cells: anti-endothelin-1 antibodies, verapamil, and octreotide

The present study investigated the mechanisms mediating the actions of the immunosuppressive drug cyclosporine A (CsA) on human pulmonary artery smooth muscle cell (PASMC) proliferation. The new hydroxyethyl derivative of D-serine(8)-cyclosporine, SDZ IMM 125, was used for comparison. CsA-induced proliferation was determined by incorporation of [(3)H]thymidine ([(3)H]Thy). CsA in the concentration range between 0.1 nM and 0.1 microM induced a concentration-dependent increase in proliferation after 24, 48, and 72 hr of incubation. Higher CsA concentrations were cytotoxic. When proliferation experiments were performed in the presence of a monoclonal antibody against endothelin-1 (ET-1), CsA-induced proliferation was totally inhibited. No inhibition occurred in the presence of the same antibody when heat-inactivated or a non-specific monoclonal antibody. In parallel, CsA increased the production of ET-1, as determined by radioimmunoassay. Incubation of PASMCs with ET-1 at the concentration range at which the latter was released by CsA induced cell proliferation. The somatostatin derivative Sandostatin (SDT; octreotide), which is an inhibitor of the growth of smooth muscle cells as well as a potent inhibitor of ET-1 secretion, inhibited both the CsA-induced ET-1 release and the increase in [3H]Thy incorporation by PASMCs. A similar effect was observed for the calcium channel blocker verapamil (VP). SDZ IMM 125 induced weaker effects than CsA in terms of PASMC proliferation and ET-1 secretion. In conclusion, CsA increased the rate of proliferation of PASMCs, while SDZ IMM 125 induced a weaker effect. Anti-ET-1 antibody, VP, and SDT significantly inhibited CsA-induced PASMC proliferation.

The adverse effects of octreotide on the healing of colonic anastomoses in rats

Octreotide, a long-acting somatostatin analogue, is widely used in gastrointestinal hypersecretory states and also for endocrine tumors in an attempt to inhibit the paracrine hormones. Although it is well known that octreotide inhibits trophic and anabolic hormones, no research has been conducted on its adverse effects on wound healing. In the present study, groups of rats were given 20 mcg/kg/day octreotide and 100 mg/kg/day hydrocortisone, the latter being the negative control group, starting 5 days preoperatively. The colonic anastomoses were assessed for healing on postoperative days (PODs) 5 and 8 by determining the bursting pressure of the anastomoses, performing histopathological analysis, and measuring the hydroxyproline content of the anastomotic tissues. Octreotide was found to affect anastomotic healing negatively on both PODs 5 and 8, but the negative effect of hydrocortisone was significant only on POD 8. No significant difference was found between the adverse effects of the two agents on POD 8. These findings indicated that octreotide has an adverse effect on the healing of colonic anastomoses in rats.

Time-dependent influence of the somatostatin analogue octreotide on the proliferation of rat astrocytes and glioma cells

The somatostatin receptor subtype sst2 was visualized by immunostaining on cultivated rat astrocytes and C6 rat glioma cells. Octreotide, a metabolically stable sst2 agonist reduced [3H]thymidine incorporation into DNA of both cell types dose-dependently only after short-time application (2-5 h), after prolonged incubation (> 12 h) no antiproliferative effect was measurable. We conclude that sst2 receptors may be desensitized. Thus, desensitization might hinder application of octreotide to reduce glial tumour growth.

The role of pharmacologic agents in blood conservation

Pharmacologic agents are welcome therapeutic weapons in the fight to conserve blood. The goals of drug therapy cross a broad spectrum of potential areas. Blood-conserving pharmacologic agents are aimed at 1) increasing blood production, 2) decreasing blood loss during active bleeding, and 3) preventing the breakdown of the formed fibrin clots. In this article, the author reviews the mechanisms of action, dosing, and adverse effects of these agents. The role of pharmacologic agents in blood conservation is significant because these agents have been shown to decrease transfusion requirements and provide significant cost savings.

Management of pancreatic carcinoma

Pancreatic cancer is the fifth-leading cause of cancer death in the United States. It is estimated that 27,000 patients die each year with this diagnosis. The overall five-year survival of patients with pancreatic cancer remains less than 5%, but some subsets of patients may have a better prognosis. Advanced imaging and laparoscopy have improved staging to better select patients for potentially curative surgery, while the operative morbidity and mortality of the Whipple resection have decreased in recent years. Non-surgical therapies in current use include chemotherapy, external-beam radiation therapy, and brachytherapy, as well as pain management. More recently, gene insertion therapy has shown promise in animal models. This review discusses current diagnostic and treatment strategies for these patients and documents the need for new strategies in the future.