Neuronal circuits in sensory system are closely connected with other nerve systems for efficient handling of sensory information.1 For example, taste sensory CHIR-99021 concentration information that reached the nucleus tractus of solitarius is principally relayed to the gustatory

cortex via the parabrachial nucleus, but also targets to the other brain area such as the cerebral cortex, hippocampus, amygdala, hypothalamus and nucleus accumbens for the better storage or recall of taste memory or the innate and instinctive response such as preference and aversion.2, 3 and 4 Thus, it is suggested that the deprivation or disruption of taste sensory relays may affect the function of those brain regions. Taste sensory system is in charge of evaluating the nutritious content of food and preventing the ingestion of toxic substances, and importantly also has the additional value of contributing to the overall pleasure and enjoyment of a meal. Eating has been viewed as a strategy to improve negative mood5 and to mask stress,6 and studies indicate that healthy, normal-weight persons regulate negative emotions by eating.7 and 8 It has been reported that decreased responses

in the reward network including the nucleus accumbens to palatable food may be a trait marker of vulnerability to depression.9 and 10 In rodents, anhedonia, a reduced sensitivity to reward, which is a core symptom of major depression, can be measured by a decreased intake of and preference for sweet solutions. Indeed, sweet solutions have been shown to rapidly calm stress responses in human Dichloromethane dehalogenase newborns,11 and GSK126 in vitro in adults, experimentally induced negative mood is improved

immediately and selectively after eating palatable food,12 suggesting that immediate positive affective reactions elicited by palatable foods diminish the impact of stress. Collectively, it is hypothesized that alterations in oral sensory information can modulate the psycho-emotional status of individuals. Lingual nerve can be damaged by dental surgery or trauma such as physical irritation, radiation, chemotherapy, or viral infection. This study was conducted to define the psycho-emotional effects of the lingual nerve damage in which oral sensory relay to the brain is disrupted, and the rats were tested for anxiety- and depression-like behaviours after bilateral transections of the lingual and chorda tympani nerves. The chorda tympani nerve joins the lingual division of the trigeminal nerve, the lingual nerve, and distributes together to the fungiform papillae on the anterior two thirds of the tongue and may reach also the anterior portion of the foliate papillae. Axons of glossopharyngeal nerve supply both tastes buds and general sensory innervations to the vallate and foliate papillae, and also tastes buds in the pharynx.13 Thus, it is expected that with bilateral transections of the lingual and chorda tympani nerves, rats may lose the sensory information from the anterior two thirds of tongue.