The effects of perfusing the lateral cerebroventricle with CaCl_2 on the febrile response and cAMP concentrations of the plasma and cerebrospinal fluid(CSF) during endotoxic fever were observed in forty experimental rabbits. The results showed that the increase of the body temperature and cAMP concentration in CSF induced by endotoxin were significantly inhibited by perfusing the lateral cerebroventricle with CaCl_2. The authors inferred that the increase of Na~+/Ca~(++) ratio led to the increase of cAMP concentration in the hypothalamus may act as an important central febrile link in endotoxic fever. In addition, cAMP may have no relation with the mechan ism that the decrease of Na~+/Ca_(++) ratio in the hypothalamus can cause the fall of the normal body temperature in rabbits.

In order to study mechanisms of endotoxin (ET) and endogenous pyrogen (EP) byperthermic ceilings, the febrile responses induced in rabbits by intravenous injection of varying doses of EP were observed, and the doses in which the febrile reactions of rabbits to ET and EP are limited by hyperthermic ceiling were identified. Furthermore, the febrile reactions of typerttermic ceiling plus different pyrogen load were observed. T, e experiment stowed: 1. The level of ET hypert ermic ceiling is notably higher in comparison to that of EP hypertiermic ceiling. The findings indicated that the mechanisms of ET fever and ET Lyperthermic ceiling are different from those of EP fever and EP hyperthermic ceiling. 2. After EP hyperthermic ceiling was added the load of ET. the altitude of fever exceeded the EP hyperthermic ceiling; but after ET hypertthermic ceiling was added the load of EP, the altitude couldn't exceed ET hyperthermic ceiling. The results suggested that ET hyperthermic ceiling contained EP hyperttermic ceiling. The latter was an important component of ET hyperttermic ceiling, but there are other factors participating in the mechanisms of ET fever and ET hyperthermic ceiling except EP.

In order to determine whether the cAMP is a central madiator and participates in the mechanism of the ET-induced fever, in the following experiments, we have compared the cAMP levels in csf, plasma to the cAMP levels in tissues of hypothalamus, brain-stem and brain-cortex during the ET-induced fever. The results obtained demonstrate: the cAMP Ievels in tissues of hypothalamus and in csf are increased markedly during the fever Compared with the normal control. These changes of the cAMP levels are paralleled and correlated apparently with the body temperature. However, there isn't any obvious change of the cAMP levels in the tissues of brain-stem, brain-cortex and in plasma during the fever. This demonstrats that the cAMP increased in csf may indirectly reflect cAMP level in hypothalamus during the fever in rabbits and the main source of cAMP increased in csf may be synthesized and released by hypothalamus.

The levels of cyclic AMP and prostaglandin E (PGE) in the brain are raised in many kinds of fever induced by various pyrogens, we also know when the ratio of Na~+/Ca~(++) is changed in the brain, the body temperature changes. So it is suggested that cAMP, PGE and the ratio of Na~+/Ca~(++) are major central mediums in febril response. It is not clear what relationship is among these three factors and what are their roles respectively in the fever mechanism? It must be very helpful for the development of fever study if we can have them correctly answered. In this paper, we change the Na~+/Ca~(++) ratio by intraventricular perfusion with EGTA or CaCl_2, and observed the temperature response, levels of cAMP and PGE_2 in c.s.f. It is found that there was a positive correlation between cAMP and the body temperature(r=0.9913, P0.05). EGTA can raise body temperature. But CaCl_2 pretreatmentd could lower the EGTA fever.

0.05) after non-fever limit (non-FL) dose and FL dose endotoxin (ET) was intravenously injected into rabbits. The increase of PGE_2 in CSF was not limited during the occurrence of ET FL. 2. Intracerebroventricular injection (ICV) of different dose of PGE_2 into rabbits induced dose-dependent fever, but there was no more rise in body temperature when the febrile response had reached a certain height. This is termed "PGE FL". 3. The concentration of cyclic adenosine-3′, 5′-monophosphate (cAMP)in CSF paralleled the fluctuation of temperature (r=0.9906, P

40 New Zealand white rabbits were used to observe the effect on the fever caused by ET (endotoxin) and EGTA [ethylene glycol bis-(?-aminoethylethylether)-N, N, N′, N′-tetraacetic acid] after ICV (intracerebroventricular) infusion of Tau and CaCl_2 into rabbits. The results showed that Tau ICV perfusion could inhibit the initial febrile response to ET and EGTA in rabbits (P0.05), which could be blocked by ICV infusion of CaCl_2. The authors suggested that Tau might increase the level of Ca~(++) in the hypothalamus and reduce Na~+/Ca~(++) ratio, then lower the fever.

In order to determine further whether cAMP and PGE takes part in the mechanism of EGTA-induced fever in the present experiment with 40 New Zealand rab bits, the influence of intravenous infusion of sodium salicylate (SS) on the febrile response and the rise of cAMP and PGE_2 concentration in c.s.f. produced by intraventricular perfusion of EGTA were observed. The results showed that intravenous infusion of SS (9.6?M/min. following an initial dose of 1.25mM) could inhibit the rise of PGE_2 concentration in c.s.f. (P0.05) after 0.6 mM EGTA was perfused into lateral cerebroventricle. The concentration of cAMP in c.s.f. was correlated apparently positively with the febrile response in EGTA-induced fever (r=0.9839, P

Aging or senescence is a process in which individuals undergo an exponential decline in vitality, leading to death. Recent years,much progress on the molecular mechanisms underlying senescence have been made. (1) Some senescence-related gene such as SEN6A,hic-5,din1 and MORF 4 have been clarified; (2) In 1997, through a set of experiments sponsered by scientists of Department of Biology Massachusetts Institute of Technology, it was found that the accommulation of extrachromosomal rDNA circles (ERC) in budding yeasts nucleolus is responsible for cell-senescence and the researchers propose that when enough of these circles accumulate, they clog the nucleus and prevent the cell from reading or replicating its genome, causing it to stop dividing and ultimately to die; (3) In another work finished by National Institute on Aging and the Geron biotech company of Melo, it was proved that a cells biological clock,which tells the cell how and how many times to divide, lies in its telomeres, little bits of DNA that coat the tips of the chromosome and it was clarified that a powerful enzyme,telomerase, with the potential to rejuvenate the human bodys aging tissues could effectively extend the shortened telomere . Although there is a long way to go, scientists still believe that it will be made reality in the future to greatly extend the life-span of human.

α-MSH is an endogenous neuropetide that is effective of all categories of expreimental inflammation. The mechanisms underlying the anti-inflammatory influence of α-MSH are reviewed in the article. α-MSH suppresses inflammation in the CNS and periphery by downregulating the activation of NF-κB, then inhibiting production of proinflammatory cytokines, nitric oxide, chemokines and adhension molecules, and increasing synthesis of anti-inflammatory cytokines. α-MSH is useful in the treatment of many pathological situations in humans.

AIM and METHODS: To investigate the effect of electrical stimulation of ventlal septal area (VSA) on discharge of pyrogen - treated thermosensitive neurons in preoptic anterior hypothalamus (POAH) region, the discharging rate of thermosensitive neurons in the POAH region of 32 New Zealand white rabbits were recorded by using extracellular microelectrode techinque. RESULTS: (1) Intraceretroventricularly (i c v) injection of interleukin - 1?(IL - 1?) caused decrease of discharging rate of warm - sensitive neurons and increased in discharging rate of cold - sensitive neurons in POAH regions. (2) These effects could be reversed by electrical stimulation of VSA. CONCLUSION: VSA may play a central role of negative regulation in thermoregulation of pyrogen - treated animal.