RELATIONSHIP between prandial drinking behavior and supersensitivity of salivary glands after superior salivatory nucleus lesions in RATS.

Prandial drinking, an increase in the number of drinking responses and secondary or non-homeostatic polydipsia in the presence of dry food, is typically associated with a deficit in salivary secretion. This study investigates the degree of salivary gland supersensitivity to pilocarpine administration after lesions to the superior salivatory nucleus (SSN), the site of origin of the parasympathetic preganglionic neurons that innervate the submandibular-sublingual (S-S) salivary glands. The main aim was to determine if there is a relationship between the degree of glandular supersensitivity, as an index of secretory deficit, and the development of prandial drinking in lesioned rats.

Place preferences induced by electrical stimulation of the external lateral parabrachial subnucleus in a sequential learning task: Place preferences induced by NLPBe stimulation.

It is known that electrical stimulation of the external lateral parabrachial nucleus (NLPBe) can sustain concurrent taste and place learning. Place preferences can be learned through different procedures. Previous studies demonstrated that electrical stimulation of the PBNLe can generate aversive and preference place learning using concurrent procedures.

Effects of oxytocin administration on the hydromineral balance of median eminence-lesioned rats.

In the clinical setting, acute injuries in hypothalamic mediobasal regions, along with polydipsia and polyuria, have been observed in patients with cerebral salt wasting (CSW). CSW is also characterised by hypovolaemia and hyponatraemia as a result of an early increase in natriuretic peptide activity. Salt and additional amounts of fluid are the main treatment for this disorder.

Differential rewarding effects of electrical stimulation of the lateral hypothalamus and parabrachial complex: Functional characterization and the relevance of opioid systems and dopamine.

Background: Since the discovery of rewarding intracranial self-stimulation by Olds and Milner, extensive data have been published on the biological basis of reward. Although participation of the mesolimbic dopaminergic system is well documented, its precise role has not been fully elucidated, and some authors have proposed the involvement of other neural systems in processing specific aspects of reinforced behaviour.

Aims And Methods: We reviewed published data, including our own findings, on the rewarding effects induced by electrical stimulation of the lateral hypothalamus (LH) and of the external lateral parabrachial area (LPBe) - a brainstem region involved in processing the rewarding properties of natural and artificial substances - and compared its functional characteristics as observed in operant and non-operant behavioural procedures.

Increased short‑term food intake after external lateral parabrachial subnucleus lesions in rats.

The vagus nerve and several brainstem nuclei to which it projects have been closely associated with food intake. The aim of this study was to determine the degree to which the same or different information on food intake is processed by this nerve and by one of these nuclei, the external lateral parabrachial subnucleus (LPbNe). For this purpose, we analyzed the solid and liquid food intake of Wistar rats subjected to vagal deafferentation with capsaicin or lesions of the LPbNe.

Tiapride prevents the aversive but not the rewarding effect induced by parabrachial electrical stimulation in a place preference task.

The parabrachial complex has been related to the processing of both rewarding and aversive signals. This pontine area is activated after the gastrointestinal administration of rewarding nutrients, in taste aversion learning, and in response to the reinforcing and aversive effects of some drugs of abuse. Electrical stimulation of this region can induce, in different animals, preference or aversion behaviors towards a place in a rectangular three-chamber maze task.

Tolerance to rewarding brain electrical stimulation: Differential effects of contingent and non-contingent activation of parabrachial complex and lateral hypothalamus.

Electrical stimulation of the parabrachial complex and related insular cortex induces concurrent conditioned place preference (CPP) in a naloxone-dependent manner. Furthermore, repeated rewarding activation of these regions generates tolerance, i.e.

Relevance of the nucleus of the solitary tract, gelatinous part, in learned preferences induced by intragastric nutrient administration.

Food preferences have been investigated in Wistar rats utilizing a learned concurrent flavor preference behavioral procedure. Previous studies have demonstrated that the perivagal administration of neurotoxin capsaicin disrupts the learning of preferences induced by intragastric administration of rewarding nutrients (pre-digested milk). The vagus nerve projects almost exclusively towards the nucleus of the solitary tract (NST), a brain medullary gateway for visceral signals.

Disruption of re-intake after partial withdrawal of gastric food contents in rats lesioned in the gelatinous part of the nucleus of the solitary tract.

Sensory information from the upper gastrointestinal tract is critical in food intake regulation. Signals from different levels of the digestive system are processed to the brain, among other systems, via the vagus nerve, which mainly projects towards the nucleus of the solitary tract (NST). The objective of this study was to analyze the participation of the gelatinous part (SolG) of the NST in short-term food intake.

Naloxone blocks the aversive effects of electrical stimulation of the parabrachial complex in a place discrimination task.

The parabrachial complex is known to participate in various rewarding and aversive processes, including those related to the learning of taste or place discrimination and the motivational effects of drugs of abuse, such as morphine. This study shows that electrical stimulation of the external lateral parabrachial (LPBe) subnucleus induces consistent place avoidance or place preference in three-compartment rectangular mazes. Administration of naloxone, an opiate antagonist, blocks both motivational effects induced by the intracranial electrical stimulation.

Satiation and re-intake after partial withdrawal of gastric food contents: A dissociation effect in external lateral parabrachial lesioned rats.

Sensory information from the gastrointestinal system can be transmitted to the brain through the vagus nerve, the intermediate-caudal region of the nucleus of the solitary tract (NST), and various subnuclei of the parabrachial complex, notably the external lateral subnucleus (LPBe). The objective of the present study was to examine the relevance of this subnucleus in satiation and food reintake after gastrointestinal food removal. LPBe-lesioned animals were subjected to a re-intake task following the partial withdrawal of gastric food contents shortly after satiation.

Chemical afferent vagal axotomy blocks re-intake after partial withdrawal of gastric food contents.

Objectives: The aim of this study was to investigate the biological process by which animals regulate meal size. An experimental procedure for its study is to examine food re-intake after partial withdrawal of gastric food contents.

Methods: The aim of the present experiments was to investigate the role of vagal afferents in food re-intake after perivagal administration of capsaicin, a neurotoxin that specifically damages weakly myelinated or unmyelinated vagal sensory axons.

Tolerance to repeated rewarding electrical stimulation of the parabrachial complex.

The parabrachial complex has been related to various rewarding behavioral processes. As previously shown, electrical stimulation of the lateral parabrachial external (LPBe) subnucleus induces opiate-dependent concurrent place preference. In this study, two groups of animals (and their respective controls) were subjected to sessions of rewarding brain stimulation daily or on alternate days.

Differential effects of naloxone on rewarding electrical stimulation of the central nucleus of the amygdala and parabrachial complex in a place preference study.

The central nucleus of the amygdala (CeA) is considered to be involved in different affective, sensory, regulatory, and acquisition processes. This study analyzed whether electrical stimulation of the PB-CeA system induces preferences in a concurrent place preference (cPP) task, as observed after stimulation of the parabrachial-insular cortex (PB-IC) axis. It also examined whether the rewarding effects are naloxone-dependent.

Animal models of Central Diabetes Insipidus: Human relevance of acquired beyond hereditary syndromes and the role of oxytocin.

The aim of this study was to review different animal models of Central Diabetes Insipidus, a neurobiological syndrome characterized by the excretion of copious amounts of diluted urine (polyuria), a consequent water intake (polydipsia), and a rise in the serum sodium concentration (hypernatremia). In rodents, Central Diabetes Insipidus can be caused by genetic disorders (Brattleboro rats) but also by various traumatic/surgical interventions, including neurohypophysectomy, pituitary stalk compression, hypophysectomy, and median eminence lesions. Regardless of its etiology, Central Diabetes Insipidus affects the neuroendocrine system that secretes arginine vasopressin, a neurohormone responsible for antidiuretic functions that acts trough the renal system.

Naloxone impairs concurrent but not sequential flavor aversion: Resorting to a flexible/explicit learning.

The role of opiate systems has been extensively studied in relation to learning and memory. Naloxone (Nx), an opiate antagonist, was administrated in concurrent (Experiment 1) and sequential (Experiment 2) flavor aversion learning (FAL) tasks. The outcomes demonstrate that Nx impairs the acquisition of concurrent but not sequential FAL.

Tolerance to repeated rewarding electrical stimulation of the insular cortex.

The insular cortex (IC) has been related to various reinforcing behavioral processes. This study examined the effect of electrical stimulation of the posterior agranular IC on concurrent place preferences. Two groups of animals and their respective controls underwent rewarding brain stimulation every day or on alternate days.

Opposite effects of oxytocin on water intake induced by hypertonic NaCl or polyethylene glycol administration.

Oxytocin (OT), a neurohormone, has been related to natriuretic and diuretic effects and also to water intake and sodium appetite. The objective of the present study was to determine the effect of subcutaneous OT administration on water intake and urine-related measures induced by the administration of hypertonic NaCl (experiment 1) or polyethylene glycol (PEG) (experiment 2). Experiment 1 showed that OT administration increases the urine volume, urinary sodium concentration, and natriuresis and reduces the water intake, water and sodium balances, and estimated plasma sodium concentration induced by hypertonic NaCl administration.

Lesions of the central nucleus of the amygdala only impair flavor aversion learning in the absence of olfactory information.

The amygdala is considered a crucial brain nucleus in different modalities of aversive conditioning, including flavor aversion learning (FAL). The importance attributed to the amygdala and its subnuclei has frequently depended on the different stimuli and procedures used in FAL tasks. In this study, FAL was impaired only in animals that had lesions in the central nucleus of the amygdala (CeA) area and also had their olfactory bulbs removed.

Rewarding effects of electrical stimulation of the insular cortex: decayed effectiveness after repeated tests and subsequent increase in vertical behavioral activity and conditioned place aversion after naloxone administration.

The insular cortex has been associated with various aversive and rewarding sensory, regulatory, and learning processes. The objective of this study was to examine the characteristics of the reinforcement induced by electrical stimulation of this brain area in rats. Results obtained confirm that electrical stimulation of the insular cortex may induce conditioned place and flavor preferences but the learning acquired is not transferred in a reversal test.

Tiapride impairs the aversive effect of electrical stimulation of the parabrachial complex in a conditioned place task.

The parabrachial complex has been related to various rewarding or aversive behavioral processes, including taste aversion learning and conditioned place aversion. This study examined the effect of tiapride, an antagonist of D2/D3 dopaminergic receptors, on place aversion induced by electrical stimulation of the external lateral parabrachial (LPBe) nucleus. Results obtained show that brain-stimulated animals avoid the area of the maze associated with electrical stimulation but show no such behavioral rejection when they receive an injection of 30 mg/kg tiapride.

Rewarding effects of the electrical stimulation of the parabrachial complex: taste or place preference?

The lateral parabrachial complex has been related to various emotional-affective processes. It has been shown that electrical stimulation of the external Lateral Parabrachial (LPBe) nucleus can induce reinforcing effects in place preference and taste discrimination tasks but does not appear to support self-stimulation. This study examined the relative relevance of place and taste stimuli after electrical stimulation of the LPBe nucleus.

Inhibition of natriuresis in median eminence polydipsia: effects after intake of diets with different osmolalities and after hypertonic NaCl administration.

Lesions in the hypothalamic median eminence (ME) induce polydipsia and polyuria in male rats. A first experiment was designed to examine the effect of salt consumption (standard 0.25 percent Na+ vs.

Conditioned place preference induced by electrical stimulation of the insular cortex: effects of naloxone.

The insular cortex has been related to various sensory, regulatory, and learning processes, which frequently include affective-emotional components. The objective of this study was to investigate the possibility of inducing reinforcing effects by electrical stimulation of this cortical region in Wistar rats. Concurrent conditioned place preference tasks were conducted for this purpose, using two rectangular mazes that differed in dimensions, texture, and spatial orientation.

The D2/D3-receptor antagonist tiapride impairs concurrent but not sequential taste aversion learning.

Taste aversion learning (TAL) is a learning modality in which the animals reject a gustatory stimulus associated with the administration of noxious visceral substances. This learning can be established by concurrent or sequential procedures that involve different anatomical and functional mechanisms and may constitute distinct learning modalities. The dopaminergic system has been related to various learning processes and goal-directed behaviours.