Development of mitral cells and olfactory bulb layers in neonatally undernourished rats

Abstract

Cell alterations in the central nervous system are consistent consequences of early undernourishment. Because little is known about the effects of neonatal udernourishment upon the main olfactory bulb (OB) in Golgi-Cox stained material, we evaluated the total OB cross-sectional area, the area of individual OB layers, and the area of type II mitral cells perikarya and their dendritic processes in undernourished Wistar rats of 7, 14, and 21 days of age. Data showed that neonatal undernourishment reduced both the OB and the individual layers areas; minimal perikarya effects and significant reductions in the number and extension of MC dendrites. Although macroneurons are formed prenatally, neonatal undernourishment at critical periods may have long-lasting effects that interfere with the functional maturity of the OB. These findings may have relevant consequences for early odor discrimination of the offspring, since olfaction is a fundamental sensorial avenue for newborn adaptive responses and maternal care.

Effects of perinatal undernutrition on the circumvallate papilla of developing Wistar rats

“…In altricial species perinatal undernutrition (PNU) during particular developmental time windows interferes, among others brain structures, with maturation of the sensory systems, as evidenced by the delayed ear and eye-opening, olfactory glomeruli and mitral cells hypoplasia, delayed myelination, reduced numbers of afferent fibers, and delayed visual, olfactory, and somatosensory electrical cortical responses (Callison and Spencer, 1968;Frias et al, 2009;Math and Davrainville, 1980;Salas and Cintra, 1973;Sima and Sourander, 1974). These brain sensory impairments are also correlated with deficient long-term cognitive processes (Córdoba et al, 1993;Salas et al, 2002;Tonkiss et al, 1991).…”

Perinatal undernourishment and handling: effects on olfactory discrimination in the newborn rat

“…), which achieves its adult characteristics only at the end of the third postnatal week. [5][6][7][8][9][10] Olfactory discrimination early in life coincides with the sensitive period of enhanced neuronal plasticity in the olfactory bulb. This activity is initially mediated by the maternal care and thereafter by nest environmental odors that induce important basic structural and functional plasticity for the pup's learning.…”

“…12 Furthermore, these alterations also affect olfactory structures (glomeruli profiles, mitral/tufted output, granule neurons, amygdala and hippocampal neuronal substrate), which delays the electrophysiological development and interferes with odor discrimination and long-term olfactory-guided behavior. 9,10,[25][26][27] During the lactating period, the mother-litter bonds are essential for the development of the newborn rat's physical, behavioral, cognitive, and endocrine responses to stress. [28][29][30] Maternal care can be disrupted if the lactating dam is exposed to stressful conditions.…”

Development of the Gusto Facial Reflex in Perinatally Undernourished Rats

“…In the past, a number of studies have shown that perinatal undernutrition in the rat delays the maturation of sensory systems and causes the expression of altered motor patterns; these effects lead to a significant deficiency of somatosensory, auditory, visual, and chemosensory stimulation that may be essential for long-term behavioral performance [1][2][3][4][5][6][7][8]. Perinatal undernutrition mainly interferes with the anatomical organization of central nervous system (CNS) areas which undergo a phase of postnatal cell proliferation; these areas include the cerebral and cerebellar cortices, the hippocampus, central amygdaloid nucleus, olfactory bulb, and solitary tract nucleus, and they participate in the head movements, mouth opening and closing, chewing, food ingestion, and chemosensory CNS integration [8,[9][10][11][12][13].…”

“…Perinatal undernutrition mainly interferes with the anatomical organization of central nervous system (CNS) areas which undergo a phase of postnatal cell proliferation; these areas include the cerebral and cerebellar cortices, the hippocampus, central amygdaloid nucleus, olfactory bulb, and solitary tract nucleus, and they participate in the head movements, mouth opening and closing, chewing, food ingestion, and chemosensory CNS integration [8,[9][10][11][12][13]. Early undernutrition affects neuronal development by reducing the cell number and their dendritic branching, and by the formation of spines with small perikarya alterations that interfere with their connectivity and neuronal interactions [7,8,[14][15][16].…”