Structural and functional consequences in the amygdala of leptin-deficient mice

Abstract

On the one hand, the emotional state can influence food intake and on the other hand, hunger can have an impact on the emotional state. Leptin, which is encoded by the ob gene, is involved in the energy homeostasis and plays a role in development of obesity. Mice deficient for leptin (ob/ob) are obese and display several behavioral alterations. It has been shown that ob/ob mice display striking changes in neuronal plasticity within the limbic system, e.g., hippocampal formation. We focus on alterations in ob/ob mice that can be related to alter processing in another part of the limbic system, the amygdala. ob/ob mice have a higher food consumption than age-matched controls, which might have an impact on the emotional state of these mice. Since the amygdala is involved in emotional processing, we analyze whether ob/ob mice display alterations in plasticity at the electrophysiological and structural level. No changes were seen in dendritic spine densities in the basolateral and lateral (LA) nucleus of the amygdala. Interestingly and in contrast to the hippocampus (Porter et al. 2013), long-term potentiation in the LA was increased in ob/ob mice. Our results indicate that amygdalar and hippocampal synaptic plasticity are regulated in different ways by leptin deficiency in accordance with the different functions of these limbic structures in stress and anxiety.

Orexin-A and endocannabinoids are involved in obesity-associated alteration of hippocampal neurogenesis, plasticity, and episodic memory in mice

“…To test if HFD and ob/ob mice present impairment in discriminating stored memories as effects of a deficit in PS, the novel object recognition (NOR) task was performed 14 after having characterized the lack of impact of obesity on baseline motor abilities. Based on the evidence that obese mice are more sensitive to the behavioral responses during spontaneous behavior or ethologically based tests 47 , the light−dark box test and open-field test were performed to exclude the influence of the obese phenotype on general motor functioning (Supplementary Fig. 1 ).…”

Effectiveness of Motivational Counseling for Lifestyle Modification in Obese Patients Using a Patient-centered Approach

“…Epworth moderate daytime sleepiness (ESS) tended to decrease without a significant difference (6.73±0. 50 Sleep duration by the end of 6 months of observation stabilized significantly (р=8.41Е-05; р<0.001) to 0.14±0.08 points, which is interpreted as an extension of sleep to more than 7 hours/night. Habitual sleep efficiency significantly improved to 0.08±0.04 points (р=4.30Е-03; р<0.01), which also indicated the effectiveness of measures and improvement of sleep by more than 85%.…”

“…The action of serotonin has been confirmed experimentally, with the peripheral administration of a tryptophanhydroxylase inhibitor, its metabolism decreases and its concentration in the blood and across the blood-brain barrier increases, and as a result, a decrease in body weight is observed even in individuals with hyperphagia and obesity [46]. Leptin is a peripheral hormone secreted by adipocytes and affects the hypothalamus and limbic system, which control emotions, motivation, behavior, according to the principle of feedback, reduces appetite and promotes weight loss [47][48][49][50][51].…”

Human Milk Processing and Its Effect on Protein and Leptin Concentrations

“…Other results revealed that both hormones affected physical growth outcomes in preterm infants [ 60 ]. Furthermore, animal studies have demonstrated that leptin deficiency is associated with structural and functional brain alteration and lower brain weight [ 24 , 25 , 61 ]. Preterm infants are at high risk for leptin deficiency after birth [ 19 , 23 ], and the low leptin concentration in pasteurized human breast milk might have an additional effect on brain maturation and development.…”