Induction of experimental allergic encephalomyelitis in a low-susceptible Albino Oxford rat strain by somatostatin analogue SMS 201-995.
OBJECTIVE
The effect of the somatostatin analogue SMS 201-995 (octreotide; OCT) on the course of experimental allergic encephalomyelitis (EAE) in the relatively resistant Albino Oxford (AO) strain of rats was studied.


METHODS
Animals were actively immunized with bovine brain homogenate in complete Freund's adjuvant. OCT was given subcutaneously in the hind legs on days 7, 8 and 9 after immunization, at a dose of 3 x 5 microg/kg/day. Rats in control groups were treated with saline or were left untreated. EAE was scored clinically and immunophenotypically, estimating by flow cytometry the changes in the popliteal lymph nodes (PLN) and spleen and monitoring immunohistologically the brain sections of rats recovered from disease.


RESULTS
In control AO rats, EAE was induced in only 2 of 22 rats (9%). In OCT-treated rats, however, EAE developed in 11 of 20 rats (55%), in comparison with 3 of 17 saline-treated animals (17%) (p <0.05). In PLN of OCT-treated rats during the clinical course of EAE, a decreased proportion of OX8+ cells was seen, followed by increases in OX39+ and W3/25+ cells on days 17 and 26. In spleen, OCT decreased the proportion of OX1+, OX39+ and OX8+ cells (on days 12 and/or 17), and increased the proportion of OX39+ cells on days 26 and 31. In the brain sections of saline-treated rats recovered from EAE, numerous Mac-1+, Mac-3+ and OX8+ cells were found. These cells were, however, absent in OCT-treated rats; instead, several W3/25+ cells were noticed.


CONCLUSIONS
These data imply that OCT increases the susceptibility of AO rats to EAE, interfering with specific and/or nonspecific defense mechanisms operating in both the initial and recovery phase of EAE.
Muhvić
Damir
D
Department of Physiology and Immunology, Medical Faculty, University of Rijeka, Rijeka, Croatia.
Barac-Latas
Vesna
V
Rukavina
Daniel
D
Radosević-Stasić
Biserka
B
D000818:Animals; D000917:Antibody Formation / Q000187:drug effects / Q000276:immunology; D000954:Antigens, Surface / Q000187:drug effects / Q000276:immunology; D015496:CD4-Positive T-Lymphocytes / Q000187:drug effects / Q000276:immunology; D018414:CD8-Positive T-Lymphocytes / Q000187:drug effects / Q000276:immunology; D049109:Cell Proliferation / Q000187:drug effects; D004195:Disease Models, Animal; D004681:Encephalomyelitis, Autoimmune, Experimental / Q000139:chemically induced* / Q000235:genetics* / Q000503:physiopathology; D005765:Gastrointestinal Agents / Q000633:toxicity; D020022:Genetic Predisposition to Disease / Q000235:genetics*; D007111:Immunity, Cellular / Q000187:drug effects / Q000276:immunology; D016130:Immunophenotyping; D008213:Lymphocyte Activation / Q000187:drug effects / Q000276:immunology; D008297:Male; D015282:Octreotide / Q000633:toxicity*; D051381:Rats; D011919:Rats, Inbred Strains; D013004:Somatostatin / Q000031:analogs & derivatives* / Q000633:toxicity*; D015854:Up-Regulation / Q000187:drug effects / Q000276:immunology
D000954:Antigens, Surface; D005765:Gastrointestinal Agents; D013004:Somatostatin; D015282:Octreotide