Effects of copaiba oil on dermonecrosis induced by Loxosceles intermedia venom

Figure 1.
Effect of treatment with copaiba oil after Loxosceles intermedia venom injection on blood cells. Platelets (a) and heterophils (c) count showed significant reduction after venom injection (4,8 μg/kg). The treatment was efficient in inhibiting the decrease of heterophils in the blood 24 hours after venom inoculation *p <0.05 / ANOVA. However, groups inoculated with venom and treated with copaíba oil showed no significant difference from the control group at total leukocyte (b) and lymphocyte count (d). n = 4 animals per experimental group.

Figure 2.
Evolution of the lesion 30 days after Loxosceles intermedia venom injection. Macroscopic comparison of animals that received only the venom, compared to those treated with copaiba oil after venom inoculation showed lesions with smaller area and with mild erythema. The copaiba oil induced a formation of thicker crust more delimited, without the presence of scarring on the skin (a). Ten days after venom injection the lesion area of the group that received the treatment with copaiba oil was larger than the untreated group (b). n = 4 animals per experimental group.

Figure 3.
Photomicrographs of the skin of rabbits 3, 10 and 30 days after L. intermedia venom inoculation in the back. The control group presented integrity of the skin layers (a/d/g). In the animals that received venom injection (4.8 µg/kg) heavy bleeding in the dermis (*), epidermal thickening (upper insert - b), the presence of intense inflammatory infiltrate in muscle (lower insert - b) and hypodermis tissue (#) and blood vessels with clot ( ) were observed 3 days after inoculation (b). In animals inoculated with venom and treated with copaiba oil, bleeding (*), injury of the epidermis (upper insert - c) and inflammatory infiltrates in muscle tissue (lower insert - c) were observed 3 days after venom inoculation (c). After 10 days, the dermal thickness was reduced in venom group (e), but the epidermis remained thick (upper insert - e); on the other hand, in the treated group, dermal thickness was reduced (f), but redefinition was detected between papillary and reticular dermis (upper insert - f). After 30 days of regeneration of the dermis, epidermis (upper insert - h) and muscle tissue, marked by the presence of central nuclei (inferior insert - h) after 30 days in the venom group (h); the treated group also showed regeneration of dermis, epidermis (upper insert - i) and muscle tissue (lower insert - i), marked by an increase in the number of hair follicles (i). n = 4 animals per experimental group.

Figure 4.
Photomicrographs of collagen on skin of rabbits 3 and 30 days after inoculation of L. intermedia venom in the back. Picrosirius red staining under optical light reveals total collagen as red, polarized light collagen type I as red fibers and collagen type III as green fibers. The control animals presented normal distribution of collagen types on the skin at 3 (a - a/d) and 30 days (a - g/j), and did not differ in total collagen quantification by hydroxyproline (b). The animals inoculated with venom at 4.8 µg/kg did not differ at day 3 post-inoculation compared to the control group (a - b/e) but showed increase of collagen deposition at 30 days (a - h/k), quantified by hydroxyproline (b *p<0.001 / ANOVA). The animal group inoculated with venom and treated with copaiba oil showed no difference at day 3 (a - c/f), but at 30 days presented less intense increase of collagen (a - i/l), quantified by hydroxyproline (b *p<0.05 / ANOVA). n = 4 animals per experimental group.