2006 Fiscal Year Final Research Report Summary
Mechanisms of suckling behavior
| Project/Area Number |
17590157
|
|---|
| Research Category |
Grant-in-Aid for Scientific Research (C)
|
| Allocation Type | Single-year Grants |
|---|
| Section | 一般 |
|---|
| Research Field |
General anatomy (including Histology/Embryology)
|
|---|
| Research Institution | Shinshu University |
|---|
Principal Investigator |
MORIIZUMI Tetsuji Shinshu University, Sch. of Med., Dept. of Anatomy, Professor, 医学部, 教授 (70157874)
|
|---|
| Co-Investigator(Kenkyū-buntansha) |
FUKUSHIMA Nanae Shinshu University, Sch. of Med., Dept. of Anatomy, Assistant Professor, 医学部, 助手 (90334888)
|
|---|
| Project Period (FY) |
2005 – 2006
|
| Keywords | Suckling / Cranial nerves / Motor nervous system / Sensory nervous system / Nerve injury / Suckling behavior / Survival / Nipple attachment time |
|---|
| Research Abstract |
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
|
