Mechanisms of suckling behavior

在新生期切除舌下神经(XII)和面神经(VII)的新生大鼠上，观察了参与母乳喂养的口周解剖结构的功能作用。XII神经控制舌的运动，由两个功能不同的分支组成：与舌突出有关的内侧支和与舌后缩有关的外侧支。切除双侧XII神经成分(主干：XII-干；内侧支：XII-MED；侧支：XII-LAT)的新生大鼠不能吸奶，也不能存活。单侧XII神经切断的新生儿表现出不同的哺乳能力，从而导致出生后3周至21岁的存活率(XII主干：38%；XII-MED：24%；XII-LAT：92%)和出生后生长发育的差异。结果表明舌头在乳房…中起着至关重要的作用，尤其是由XII神经支配的突出的肌肉成分。本研究旨在探讨在不同发育阶段切断单侧或双侧VII、XII神经成分的大鼠，观察损伤对大鼠存活和生长的影响。在哺乳期，单侧和双侧的XII干或XII内侧神经损伤导致乳汁摄取障碍，神经损伤大鼠存活率降低，生长发育迟缓。在过渡和咀嚼阶段，只有双侧的XII躯干或XII内侧神经损伤才会导致摄食障碍，随后这些动物的存活率和生长迟缓。新生早期单侧VII神经损伤对摄食量的影响恶化，导致大鼠存活率下降和严重的生长迟缓。结果表明，切断XII和VII族神经的大鼠的存活和生长发育因神经损伤时的神经损伤和动物发育年龄的不同而有很大差异。单侧LN损伤仔鼠未出现哺乳障碍，乳头附着时间无明显缩短(P11仔鼠：559±16秒；为对照的105%)，存活率较高(P11：100%)。双侧LN损伤仔鼠表现为哺乳障碍，乳头附着时间明显缩短(P11仔鼠：220±54秒；为对照组的42%)，存活率低(P1：33%；P11：41%)。双侧眶下神经损伤或双侧小梁切除的幼鼠根本没有表现出任何乳头附着，也没有幸存者，证实了上唇感觉和嗅觉在哺乳中的关键作用。基于这些发现，我们得出结论，舌感对哺乳非常重要，但不是必不可少的。较少

Functional roles of the perioral anatomical structures involved in breastfeeding were examined in newborn rat pups in which the hypoglossal (XII) and facial (VII) nerves had been resected at the neonatal stage. The XII nerve controls tongue movement and is comprised of two functionally distinct branches : the medial branch related to protrusion of the tongue and the lateral branch related to its retraction. Newborn rat pups with bilateral resection of either of the XII nerve components (main trunk : XII-trunk ; medial branch : XII-med ; lateral branch : XII-lat) failed to suckle milk and did not survive. Unilateral XII nerve-resected neonates showed different milk-suckling capabilities, which thus resulted in differences in survival rate (XII-trunk : 38% ; XII-med : 24% ; XII-lat : 92%) and postnatal growth during the postnatal three weeks until P21. The results indicate a crucial role of the tongue, especially of protruding muscular elements innervated by the XII-med nerve, in breastf … More eeding.The present study was performed to determine the effects of VII and XII nerve injuries on the survival and growth of rats in which the unilateral or bilateral VII and XII nerve components had been resected at different developmental stages. In the suckling period, unilateral as well as bilateral injuries in the XII-trunk or XII-med nerve produced disturbed milk intake, lower survival rates and growth retardation in the nerve-injured rats. In the transition and mastication periods, only bilateral injury in the XII-trunk or XII-med nerve produced disturbed food intake followed by lower survival rates and growth retardation in those animals. The unilateral VII nerve injury at the early neonatal stage caused deteriorating effects on food intake resulting in lower survival rate and severe growth retardation in the nerve-injured rats. The results indicate that the survival and growth of XII and VII nerve-resected rats differ considerably depending on the nerves injured and the developmental ages of the animals at the time of nerve insult.Functional role of lingual nerve (LN) in breastfeeding was investigated in rat pups during the suckling period. Unilaterally LN-injured pups did not show suckling disturbance with absence of any shortening (P11 pups : 559 ±16 sec ; 105% of the control value) in nipple attachment time and the survival rate remained high (P11 : 100%). Bilaterally LN-injured pups showed suckling disturbance with marked shortening (P11 pups : 220 ± 54 sec ; 42% of the control value) in nipple attachment time and a low survival rate (P1 : 33% ; P11 : 41%). Bilaterally infraorbital nerve-injured or bilaterally bulbectomized pups did not show any nipple attachment at all and there were no survivors, confirming the crucial roles of upper lip sensation and olfaction in suckling. Based on these findings, we conclude that tongue sensation is very important, but not essential for suckling. Less