Lão hóa tế bào là một hiện tượng khi các tế bào phân lập trở nên hạn chế khả năng phân chia trong môi trường nuôi cấy. Lão hóa cơ thể đề cập đến quá trình trưởng thành và già nua của sinh vật. Những quá trình này không liên quan đến cơ chế apoptosis (chết tế bào theo chương trình). | 48 PATHWAYS OF CLINICAL FUNCTION AND DISABILITY A Tail pinch Social interaction C 50 40 I 30 I 20 o E I 10 0 -6 0 6 12 18 24 30 36 42 48 54 60 -6 0 6 12 18 24 30 36 42 48 54 60 Time min Time min Figure Changes in brain nucleus accumbens or NAcc muscle and skin temperatures. A Relative change vs. baseline B brainmuscle and skin-muscle temperature differentials and C locomotion in male rats during one-minute tail pinch and social interaction with another male rat. Filled symbols indicate values significantly different versus baseline P . NAcc and muscle temperatures a biphasic down-up fluctuation in skin temperature and locomotor activation. Although the duration of both stimuli was 1 minute temperature and locomotor responses were more prolonged with different time courses for each parameter. Temperature changes in the NAcc and muscle generally paralleled each other but increases in the NAcc were more rapid and stronger than those in muscle resulting in a significant increase in NAcc-muscle temperature differentials during the first 4 to 6 minutes after stimulus onset Fig. . Since temporal muscle is a nonlocomotor head muscle that receives the same arterial blood from common carotid artery as the brain this recording location provides not only a measure of body temperature but also allows one to control for the contribution of heat inflow by arterial blood. The increase in brain-muscle differential therefore suggests brain activation as the primary cause for intrabrain heat production rather than heat delivery from the periphery and a factor that determines via activation of effector mechanisms subsequent body hyperthermia. Increase in brainmuscle differential correlated more tightly with locomotor activation which increased momentarily and slowly decreased for about 20 minutes Fig. . Each stimulus also induced rapid and robust decreases in skin temperature suggesting acute vasoconstriction Baker Cronin Mountjoy 1976 . While changes in skin .
