Objectives. Previously we have shown that 20 days after the tumor cells injection smaller melanomas have been developed in chemically sympathectomized mice in comparison with animals having intact sympathetic nervous system. However, it is known that chemical sympathectomy reduces the sympathetic neurotransmission only temporarily. In the present study, we monitored the survival of the sympathectomized mice with melanoma with an attempt to find out how long the suppressing effect of sympathectomy on the melanoma growth may endure.
Methods. The chemical sympathectomy was performed by intraperitoneal injection of neurotoxin 6-hydroxydopamine in male C57BL/6J mice. Seven days later, the animals were injected subcutaneously with B16-F10 melanoma cells. Then, melanoma development, survival of the tumor-bearing mice and weight of the developed tumor mass were analyzed.
Results. Sympathectomy delayed the development of the palpable tumors (18th day vs.14th day) and significantly prolonged the survival of the tumor-bearing mice (median 34 days vs. 29 days). However, the weight of the developed melanoma was significantly increased in the sympathectomized mice in comparison with the animals having intact sympathetic nervous system.
Conclusions. The data of the present study showed that effect of the chemical sympathectomy, performed before the tumor growth induction, persisted even at the time when sympathetic nerves started to regenerate that resulted in a prolonged survival of the mice with melanoma. However, comparing to our previous study, in which we have shown a reduced tumor mass in earlier stages of the tumor growth, specifically 20 days after melanoma cells injection, now we indicate that in later stages of the melanoma progression, the tumor mass was significantly increased in sympathectomized animals. These contra-intuitive findings may indicate that interventions affecting the sympathetic nervous system may exert complex effect on the tumor progression. Based on these data we may suggest that the potential therapeutic interventions affecting the sympathetic signaling in the tumor tissue and its microenvironment should attenuate the sympathetic neurotransmission not only temporarily but till the complete regression of the tumor tissue.
The maintenance of the body weight at a stable level is a major determinant in keeping the higher animals and mammals survive. Th e body weight depends on the balance between the energy intake and energy expenditure. Increased food intake over the energy expenditure of prolonged time period results in an obesity. Th e obesity has become an important worldwide health problem, even at low levels. The obesity has an evil effect on the health and is associated with a shorter life expectancy. A complex of central and peripheral physiological signals is involved in the control of the food intake. Centrally, the food intake is controlled by the hypothalamus, the brainstem, and endocannabinoids and peripherally by the satiety and adiposity signals. Comprehension of the signals that control food intake and energy balance may open a new therapeutic approaches directed against the obesity and its associated complications, as is the insulin resistance and others. In conclusion, the present review summarizes the current knowledge about the complex system of the peripheral and central regulatory mechanisms of food intake and their potential therapeutic implications in the treatment of obesity.
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