[Neural structural relations between the chemosensitive areas of the ventrolateral medulllary surface and the medullary nuclei in rats]

Abstract

Experiments were done on 30 chloralose-urethane anesthetized Sprague-Dawley strain rats. The ventrolateral medullary surface was exposed and a small millipore filter paper soaked with horseradish peroxidase (HRP) was applied locally to different parts of the underlying chemosensitive areas separately, trying to identify location of the HRP-stained cells. (1) After HRP application to the rostral area (n = 10), quite a number of labelled cells were distributed at the ventrolateral part of the nucleus of trapezoid body (Tz), the lateroventral periolivary nucleus (LVPO) and the retrotrapezoid nucleus (NRT). (2) After HRP application to the caudal area (n = 10), HRP labelled cells were mainly located at the lateral reticular nucleus (LRt) and the ventral part of at the lateral paragigantocellular nucleus LPGi. (3) After HRP application to the intermediate area (n = 6), only 8 HRP labelled cells were observed at the (LPGi) in 6 rats. (4) After HRP application to the control area (n = 4), only 6 HRP labelled cells were found at the rostral ventrolateral reticular nucleus (RVL). The above findings demonstrated the existence of the neural structural relations between the chemosensitive areas of the ventrolateral medullary surface and Tz, LVPO, NRT, LPGi, LRt, which supports that all these nuclei might participate in the central chemoreception of respiration.