Examination of the hyposesis of thermoredulatory module in the hypothalamus.

下丘脑中的温度敏感神经元，特别是视前区（PO）中的温度敏感神经元，在温度调节中起重要作用（Boulant，1980; Simon等人，1986），但是关于下丘脑中信号处理的许多假设仍然没有得到验证，因为我们没有足够精确的关于那里神经元“网络”的信息。虽然长期以来，温敏神经元发送驱动热损失的传出信号和冷敏神经元发送驱动热产生的传出信号几乎是一种信仰，但我们发现温敏神经元用于控制热产生以及热损失（Zhang et al.，1995年）。但是我们已经获得证据表明PO仅仅是神经元群的集合，每个神经元群向每个效应器发送其自己的传出信号，并且这些群在没有彼此连接的情况下起作用（Kanosue等人，1997年）。在本研究中，基于这些发现，我们进一步分析了下丘脑和中脑的温度调节神经网络。首先，我们分析了非颤抖产热的神经网络。电刺激下丘脑腹内侧可引起棕色脂肪组织产热。但同样的刺激在视前区的升温过程中没有效果，这意味着PO向VMH发送抑制信号。第二，通过注射抑制性物质蝇蕈醇来研究后下丘脑的作用。蝇蕈醇注射液可抑制冷诱发的寒战，提示寒战兴奋神经元位于下丘脑后部。第三，DLH被注射到PAG的腹后区，它促进了非颤抖性产热。逆行示踪CTB注射到延髓中缝标记的神经元在PAG的非颤抖性产热促进。兴奋信号似乎从PAG向中缝发出。

Thermosensitive neurons in the hypothalamus, especially in the preoptic area (PO), play important roles in thermoregulation (Boulant, 1980; Simon et al., 1986), but many hypotheses about signal processing in the hypothalamus have remained untested because we don't have precise enough information about the neuronal "network" there. Although it had long been almost an article of faith that warm-sensitive neurons send efferent signals driving heat loss and cold-sensitive neurons send efferent signals driving heat production, we found that warm-sensitive neurons work for the control of heat production as well as heat loss (Zhang et al., 1995). But we have obtained evidence that the PO is simply an assembly of neuronal groups, each sending its own efferent signals to each effector, and that these groups function without connections to each other (Kanosue et al., 1997). In the present study, based upon these findings, we further analyzed the neural network for thermoregulation in the hypothalamus and the midbrain. First, we analyzed the nertwork for nonshivering thermogenesis. Electrical stimulation of the ventromedial hypothalamus elicited thermogenesis of the brown adipose tissure. But the same stimulus had no effect during warming the preoptic area, which means that the PO send inhibitory signals to the VMH. Second, the role of the posterior hypothalmus was investigated by injecting inhibitory substance muscimol. Muscimol injection suppressed cold-induced shivering, which indicates that the excitatory neuron for shivering locates in the posterior hypothalamus. Third, DLH was injected into the ventropoterior region of the PAG and it facilitated nonshivering thermogenesis. The retrograde tracer CTB injection into the medullary raphe labeled neurons in the PAG where nonshivering thermogenesis was facilitated. The excitatory signal seems to decsend from the PAG to the raphe.