Medial parabrachial nucleus neurons modulate d-fenfluramine-induced anorexia through 5HT2C receptors.

We previously reported that lesions of the medial parabrachial nucleus (PBN) enhanced d-fenfluramine (DFEN)-induced anorexia; a finding that suggests these lesions may potentiate the release of serotonin (5HT) or increase the postsynaptic action of 5HT. In the present study, we used SB 206553 (a 5HT2B/2C receptor antagonist) or m-CPP (a 5HT2C/1B receptor agonist) in a standard behavioral procedure (deprivation-induced feeding) to further explore the role of the medial PBN in drug-induced anorexia. In Experiment 1, DFEN (0 or 1.

Excitotoxic lesions of the gustatory thalamus spare simultaneous contrast effects but eliminate anticipatory negative contrast: evidence against a memory deficit.

Using consummately contrast procedures and the same taste stimuli (0.15% saccharin and 1.0 M sucrose), the authors tested the hypothesis that lesions of the gustatory thalamus disrupt gustatory memory in 2 experiments.

Effects of excitotoxic lesions of the gustatory thalamus on latent inhibition and blocking of conditioned taste aversion in rats.

The influence of bilateral excitotoxic lesions of the gustatory thalamus on latent inhibition and blocking of conditioned taste aversion (CTA) was examined in two experiments. In Experiment 1, rats with thalamic lesions showed normal latent inhibition by acquiring a CTA that was significantly weaker when the conditioned stimulus (CS) was familiar than when it was novel. In Experiment 2, the preconditioned element (sodium chloride) of a compound CS blocked the acquisition of a CTA to the novel element (sucrose) in normal rats.

Excitotoxic lesions of the lateral parabrachial nucleus do not prevent cholecystokinin-induced suppression of milk intake in rats.

We examined the effect of lateral (visceral) and medial (gustatory) parabrachial nucleus (PBN) lesions on the suppression of milk intake induced with cholecystokinin (CCK) in 24 h food-deprived rats. Irrespective of CCK dose, each type of PBN lesion significantly elevated the consumption of milk. Neither medial nor lateral PBN lesions had any discernible influence on the anorectic action of CCK, however.

Gustatory thalamus lesions eliminate successive negative contrast in rats: evidence against a memory deficit.

Successive negative contrast is the exaggerated reduction of licking that occurs when rats expecting a high-value reward are given a low-value reward. This effect is typically investigated with a 24-hr retention interval between access periods. The present experiment tested the hypothesis that the absence of successive negative contrast in rats with bilateral lesions of the gustatory thalamus (GT) is due to a memory deficit.

Medial versus lateral parabrachial nucleus lesions in the rat: effects on mercaptoacetate-induced feeding and conditioned taste aversion.

The two experiments of the present study examined the influence of bilateral electrophysiologically-guided ibotenic acid lesions of the medial (gustatory) and lateral (viscerosensory) subdivisions of the parabrachial nucleus (PBN) on lipoprivic feeding and on the acquisition of a conditioned taste aversion. In Experiment 1, mercaptoacetate (0, 400, 600, or 800 micromol/kg) failed to enhance food intake in normal rats maintained and tested on standard laboratory chow. In the same procedure, rats with lesions of the medial or lateral PBN consumed less food during baseline but nonetheless were sensitive to the orexigenic action of mercaptoacetate.