Srivastava A K, Srivastava Y P, Gupta P P
Indian J Exp Biol. 1989 Jun;27(6):548-50.
Intracerebroventricular (icv) injection of methyldopa induced body temperature changes in the rabbits. The dose of 100 micrograms/kg did not produce any significant change on body temperature whereas 250 micrograms/kg of the drug induced hyperthermia. Higher dose of 500 micrograms/kg produced initial hypothermia which was followed by hyperthermia. On further increase of the dose to 1 mg/kg, consistent hypothermia was evident. Prazosin, a specific post-synaptic alpha 1 adrenoceptor blocker, induced hypothermia whereas piperoxan (presynaptic alpha 2 antagonist) produced hyperthermia. The pretreatment with prazosin, blocked the hyperthermic response of methyldopa. The initial hypothermia by 500 micrograms/kg of methyldopa was also potentiated. The pretreatment with piperoxan completely blocked the hypothermia but had no effect on hyperthermic response of methyldopa. Pretreatment of rabbits with both prazosin and piperoxan completely blocked the hypothermia as well as hyperthermic response of methyldopa. Thus it appeared that both presynaptic alpha 2 and postsynaptic alpha 1 adrenoceptors are involved in central thermoregulation in rabbits.
脑室内注射甲基多巴可引起家兔体温变化。100微克/千克的剂量对体温没有产生任何显著变化，而250微克/千克的该药物可引起体温过高。500微克/千克的更高剂量会产生初始体温过低，随后是体温过高。当剂量进一步增加到1毫克/千克时，持续的体温过低很明显。哌唑嗪，一种特异性突触后α1肾上腺素能受体阻滞剂，可引起体温过低，而哌罗克生（突触前α2拮抗剂）则产生体温过高。用哌唑嗪预处理可阻断甲基多巴的体温过高反应。500微克/千克甲基多巴引起的初始体温过低也得到增强。用哌罗克生预处理可完全阻断体温过低，但对甲基多巴的体温过高反应没有影响。用哌唑嗪和哌罗克生对家兔进行预处理可完全阻断甲基多巴的体温过低以及体温过高反应。因此，似乎突触前α2和突触后α1肾上腺素能受体都参与了家兔的中枢体温调节。
