Abstract
Play development in juvenile rats depends on specific sensory signals integrated at cortical, limbic and brain stem levels to modulate motoric, metabolic, motivational and social responses. Neonatal undernourishment disrupts the morphological and functional organization of the brain for adaptive responses including play performance. These alterations may be restored by preweaning exposure to sensory-enriched environments. This study was designed to determine in four experimental groups, Control (LC), Underfed (LU), Control Ligated/Stimulated (LCS), and Underfed Ligated/Stimulated (LUS), whether changes in juvenile play of neonatally underfed male rats by the nipple-ligated procedure of F0 dams and/or the handling of F1 rats may restore the deficiencies in juvenile play performance. The pinning frequency values in LC, LCS and LUS groups consistently increased until reaching a significant peak between postnatal days (PDs) 25 and 50 and then gradually declining until PD 60, when the play in pairs was significantly higher compared with the play in groups that follows the same sequence but with lower values in the stimulated groups. The results may reflect poor maternal care and lower somatosensory stimulation; and the sensory massage of LU F1 pups compared with the LC, LUS, and LCS rats. Fewer dorsal body contacts occurred in LU and LUS rats when playing in pairs than in groups. Results suggest that although handling has salutary effects on neuronal play structures, the reduced levels of total pinning and dorsal contacts, mainly in the play of rat pairs in LCS vs. LUS groups, were not fully recovered.
Highlights
This study was designed to determine in four experimental groups, Control (LC), Underfed (LU), Control Ligated/Stimulated (LCS), and Underfed Ligated/Stimulated (LUS), whether changes in juvenile play of neonatally underfed male rats by the nipple-ligated procedure of F0 dams and/or the handling of F1 rats may restore the deficiencies in juvenile play performance
The pinning frequency values in ligated control (LC), LCS and LUS groups consistently increased until reaching a significant peak between postnatal days (PDs) 25 and 50 and gradually declining until PD 60, when the play in pairs was significantly higher compared with the play in groups that follows the same sequence but with lower values in the stimulated groups
Somatosensory stimulation is a relevant source of influence to modulate the expression of specific motor responses of young rats, including maternal anogenital licking, huddling, grooming, suckling, and retrieving, elicited by sensitive skin receptors located in strategic areas of the body to provoke adaptive motoric responses including juvenile play [11] [12] [13] [14] [15]
Summary
During the lifespan of rats, the neuronal mechanisms underlying juvenile play. The available information is sometimes contradictory or provides poor support to the neuronal mechanisms underlying this basic juvenile neuromotor activity both in healthy and in handicapped subjects [8]. Somatosensory stimulation is a relevant source of influence to modulate the expression of specific motor responses of young rats, including maternal anogenital licking, huddling, grooming, suckling, and retrieving, elicited by sensitive skin receptors located in strategic areas of the body to provoke adaptive motoric responses including juvenile play [11] [12] [13] [14] [15]
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