Glutamatergic control of a pattern-generating central nucleus in a gymnotiform fish.

The activity of central pattern-generating networks (CPGs) may change under the control exerted by various neurotransmitters and modulators to adapt its behavioral outputs to different environmental demands. Although the mechanisms underlying this control have been well established in invertebrates, most of their synaptic and cellular bases are not yet well understood in vertebrates. Gymnotus omarorum, a pulse-type gymnotiform electric fish, provides a well-suited vertebrate model to investigate these mechanisms. G. omarorum emits rhythmic and stereotyped electric organ discharges (EODs), which function in both perception and communication, under the command of an electromotor CPG. This nucleus is composed of electrotonically coupled intrinsic pacemaker cells, which pace the rhythm, and bulbospinal projecting relay cells that contribute to organize the pattern of the muscle-derived effector activation that produce the EOD. Descending influences target CPG neurons to produce adaptive behavioral electromotor responses to different environmental challenges. We used electrophysiological and pharmacological techniques in brainstem slices of G. omarorum to investigate the underpinnings of the fast transmitter control of its electromotor CPG. We demonstrate that pacemaker, but not relay cells, are endowed with ionotropic and metabotropic glutamate receptor subtypes. We also show that glutamatergic control of the CPG likely involves two types of synapses contacting pacemaker cells, one type containing both α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) and N-methyl-d-aspartate (NMDA) receptors and the other one only-NMDA receptor. Fast neurotransmitter control of vertebrate CPGs seems to exploit the kinetics of the involved postsynaptic receptors to command different behavioral outputs. The prospect of common neural designs to control CPG activity in vertebrates is discussed.NEW & NOTEWORTHY Underpinnings of neuromodulation of central pattern-generating networks (CPG) have been well characterized in many species. The effects of fast neurotransmitter systems remain, however, poorly understood. This research uses in vitro electrophysiological and pharmacological techniques to show that the neurotransmitter control of a vertebrate CPG in gymnotiform fish involves the convergence of only-NMDA and AMPA-NMDA glutamatergic synapses onto neurons that pace the rhythm. These inputs may organize different behavioral outputs according to their distinct functional properties.

Recognition of taste in patients during antineoplastic therapy with platinum drugs.

Taste changes caused by the use of platinum drugs have been described. However, few studies qualify the impaired tastes and whether these changes are derived exclusively from chemotherapy (QTx). AIMS: Evaluation of changes in sweet, sour, salty, bitter, and umami tastes in patients receiving QTx with platinum drugs was the aim of this study. METHODS: A total of 43 subjects, 21 from the study group and 22 from the control, were studied in two time periods, one before the start of QTx (T0) and another after two cycles of QTx (T1). The usual dietary intake, body mass index (BMI), handgrip strength and fatigue (through the fatigue pictogram) were evaluated to characterize the group studied. Taste Strips tests were performed for all 4 tastes and umami was studied by comparing Likert's scale using monosodium glutamate (GMS) food. Statistical analysis was performed using repeated measures (ANOVA), mixed model, with significance level p≤0.05. RESULTS: Salty and sour were the most affected tastes in the study group (p = 0.001 and 0.05); as well as the ionotropic receptors (p = 0.02) responsible for identifying these tastes. There was a difference between the times for BMI, dynamometry and impact in daily activities, by the fatigue pictogram (p = 0.008, 0.009 and 0.006 respectively). CONCLUSION: These findings suggest an important role in altering taste recognition, mainly in salty and sour tastes, identified by ionotropic receptors, which seems to be related to dietary changes. QTx has demonstrated a contribution to impairment of functionality and fatigue.