Undernutrition produces morphological brain alterations
and cognitive deficiencies in children of underdeveloped countries. The central
nervous system (CNS) alterations mainly interfere with the anatomical
organization of areas undergoing a phase of intense postnatal cell
proliferation, disrupting plastic processes like learning, memory, and phonation.
In the rat pup, prenatal malnutrition interferes with the elaboration of
ultrasonic vocalizations (USVs) by poorly understood mechanisms. The neuronal
caudal portion of the nucleus ambiguus (Ambc) innervates the laryngeal
intrinsic muscles to produce phonation, a basic USV communication system.
During postnatal development, enhanced plasticity phenomena play a fundamental
role in improving brain function. Thus, the massage stimulation (MS) may
accelerate growth and induce neurogenesis in different areas of the brain. The
current study analyzed the effects of a daily 10-min MS on the dendritic tree
and perikarya measurements of Ambc multipolar motoneurons (Golgi-Cox) of
perinatally underfed (U), control (C), control massage-stimulated (CMS), and
underfed massage-stimulated (UMS) groups at postnatal days (PDs) 8, 12, and
15. The data indicated that the dendritic scores were reduced (p < 0.05) in
both number and density at PD8 and PD15 in the U subjects and that MS increased
the values of these parameters (p < 0.05). In addition, MS induced body
weight gain in both U and CMS groups, and it enhanced the dendritic density in
CMS subjects. These results show that MS during the pre-weaning period restores
the plastic properties of the Ambc over the hypoplastic multipolar motoneuron
after the alterations caused by perinatal undernutrition.