Effects of electrolytic bilateral symmetric lesions of the arcuate nucleus on the phagocytic activity and on the phagocytic response in rats.

Previous researches of Cluj-Napoca laboratories of Physiology (Benetato, Baciu et al., 1945, 1946, 1947) demonstrated that direct electrical stimulation of the tubero-mammillary area in dogs increases, in the following hours, the blood polymorphonuclears phagocytic activity. By contrast, electrical damage of the same region produces a depression of the basal phagocytic activity and a blocking of the phagocytic response (Baciu et al., 1958, 1988). In the present research we assumed there is a stimulating effect of the arcuate nucleus, located in this area, on the phagocytic activity of blood neutrophils. We used an anodal current to stereotaxically induce lesion of the arcuate nucleus in six rats. A control group of six animals was used. Five days later, phagocytic response was induced with a Gram negative bacterial extract given i.v. The results demonstrated a decrease of the phagocytic activity from 164.31 +/- 17 bacteria engulfed by 100 neutrophils in controls, to 138 +/- 12.8 in the lesioned group p < 0.05. Phagocytic response after five hours appears depressed in the lesioned group (138 +/- 12.8 to 156.25 +/- 13.3, p < 0.05). Similar results were obtained after 24 hours. In control animals the response is very significant after 5 and 24 hrs., respectively, (p < 0.001). In conclusion, the arcuate nucleus is moderately involved in sustaining the basal phagocytic activity of blood neutrophils. It has an important role in phagocytic response.

Effects of thymectomy on blood neutrophils phagocytic activity and phagocytic response in mice.

The role of the thymus in maintenance of the basal phagocytosis of blood neutrophils and eliciting the phagocytic response, induced by i.v. Escherichia coli, was studied in 9 NMRI thymectomized and in 12 control mice. Thymectomy depresses the percentage of phagocyting neutrophils from 70.91 +/- 0.9 (mean +/- SEM) in controls, to 61.49 +/- 2.33 in the thymectomized rats. Phagocytic activity, as assessed by the number of bacteria engulfed by 100 neutrophils, was also lower in thymectomized mice (114.42 +/- 7.52) than in controls (163.71 +/- 4.53). A phagocytic response to i.v. Escherichia coli could nevertheless be noted in thymectomized mice, their phagocytic activity rising from the basal activity of 114.42 +/- 7.52 to 142.19 +/- 5.40 three hours after injection of Escherichia coli, while in control animals this activity rose from 163.71 +/- 4.53 to 216.46 +/- 12.91. These results may, at least partially, explain the recurrent infections and the septicemia occurring in children with Down's syndrome. It is suggested that the thymus, as an endocrine organ, may be involved in maintaining the basal phagocytic activity of blood neutrophils, while the phagocytic response is modulated by extrathymic mechanisms.

Reticulin-M, an antianaphylactic peptide secreted by reticulo-endothelial system.

I. Moldovan (1923) demonstrated in the blood ultrafiltrate from anaphylactically prepared guinea pigs, which believed to anaphylactic shock, or which were previously injected with coloidal substances as India ink to stimulate the RES, an antianaphylactic principle named Reticulin-M(R). Authors extracted R from organs rich in RES with acetone, established their, peptidic nature and tested it on anaphylactic prepared guinea pig uterine horns in vitro. The peptides were fractioned by high voltage paper electrophoresis. The fractions were cut up in four groups, eluted and tested. The second basic group was identified as active and concentrated by acetone, recipitation. In conclusion several techniques were used to obtain, to test, to isolate and to concentrate R, a natural antianaphylactic peptidic factor, which may be a cytokine.