Trigeminal deafferentation and ingestive behavior in rats.

Abstract

For studying the role of orosensory input in the control of ingestive behavior, rats were subjected to varying degrees of trigeminal deafferentation. Somatosensory branches that convey touch, temperature, and pain from the oral cavity were sectioned selectively, and innervation of the muscles of mastication and taste afferents were left intact. Severe intake deficits were produced, which included aphagia, adipsia, and prolonged hypophagia accompanied by a corresponding decrease in body weight. The deficits were proportional to the extent of deafferentation and were most severe when upper and lower portions of the mouth were affected. Although somatosensory impairment affected the organization of the consummatory response, all rats could bite, chew, and lick. Analysis of feeding patterns of minimally (mandibular) deafferented rats showed that the animals compensated for the consummatory inefficiency by increasing meal duration but failed to initiate meals at the normal rate, thus keeping food intake below normal levels. These results suggest that oral somatosensory input is critical for the mechanisms that regulate ingestive behavior.

Higher Levels of Early Childhood Caries (ECC) Is Associated with Developing Psychomotor Deficiency: The Cross- Sectional Bi-Township Analysis for The New Hypothesis

“…Previous studies in the field have shown and suggested that high levels of ECC, or alike, may result in early decays [2,3], oral-facial pain, reduced dietary intakes, loss of weight or/and sleep, accompanied by a poorer quality of life [2,3,4,5,6]. These conditions could lead to lowered mastication on the occlusal forces, the brain’s neurologic activation, or even some interferences with the metabolism and intellectual development [7,8,9], where the appropriate stimuli are linked to the synapses on the glial (or dendritic) cells for the neuro-physiological functions [10,11]. It has been previously suggested that severe caries and ECC may affect children’s’ verbal skills for proper communications and also weight loss along with certain developmental delays or deficiencies [12,13].…”

Mastication-related neurons in the orofacial first somatosensory cortex of awake cats

“…The importance of oral somatosensory inputs was indicated by observations of behavior after deafferentation (M iller, 1981;Inoue et al, 1989). On the other hand, extracellular activity recorded in the mandibular division of Gasserian ganglion in rabbits has shown that no intraoral mechanoreceptive afferents discharged during imposed jaw movements or mastication unless their mechanoreceptive ® elds were contacted.…”

Maturation of Brainstem Reflex Mechanisms in Relation to the Transition from Liquid to Solid Food Ingestion

“…Subsequently the tongue moves forward under the food item retained by the teeth and rugae; repe tition of these movements gradually moves the food backwards in the mouth [Thexton, 1984]. The same process for solid food transport has also been de scribed in the rabbit by Ardran and Kemp [1960] and increased gape, when ingesting solids as compared to liquids, has been re ported in rats [Hiiemae and Ardran, 1968], opossums [Hiiemae, 1976], pigs [ProcterGray, personal communication] and liz ards [Smith, 1984], Conversely, a decreas ed gape and an inability to ingest hard food follows a reduction in trigeminal sen sory input, although the ability to ingest semi-solids is retained [Miller, 1981]. The 'additional jaw opening' movement there fore appears to be an important subunit of motor performance [Evarts, 1982] which is triggered by a particular pattern of oral stimulation arising from contact with solid food.…”