Hyperlipidemic diet causes loss of olfactory sensory neurons, reduces olfactory discrimination, and disrupts odor-reversal learning.

Currently, 65% of Americans are overweight, which leads to well-supported cardiovascular and cognitive declines. Little, however, is known concerning obesity's impact on sensory systems. Because olfaction is linked with ingestive behavior to guide food choice, its potential dysfunction during obesity could evoke a positive feedback loop to perpetuate poor ingestive behaviors. To determine the effect of chronic energy imbalance and reveal any structural or functional changes associated with obesity, we induced long-term, diet-induced obesity by challenging mice to high-fat diets: (1) in an obesity-prone (C57BL/6J) and obesity-resistant (Kv1.3(-/-)) line of mice, and compared this with (2) late-onset, genetic-induced obesity in MC4R(-/-) mice in which diabetes secondarily precipitates after disruption of the hypothalamic axis. We report marked loss of olfactory sensory neurons and their axonal projections after exposure to a fatty diet, with a concomitant reduction in electro-olfactogram amplitude. Loss of olfactory neurons and associated circuitry is linked to changes in neuronal proliferation and normal apoptotic cycles. Using a computer-controlled, liquid-based olfactometer, mice maintained on fatty diets learn reward-reinforced behaviors more slowly, have deficits in reversal learning demonstrating behavioral inflexibility, and exhibit reduced olfactory discrimination. When obese mice are removed from their high-fat diet to regain normal body weight and fasting glucose, olfactory dysfunctions are retained. We conclude that chronic energy imbalance therefore presents long-lasting structural and functional changes in the operation of the sensory system designed to encode external and internal chemical information and leads to altered olfactory- and reward-driven behaviors.

A brief intervention may affect parents' attitudes toward using less physical punishment.

Ninety-six parents in a preschool and pediatric clinic participated in a randomized study of a brief parenting intervention. The Attitudes Toward Spanking (ATS) scale was measured at baseline, and, on average, 4 months postintervention. Higher ATS scores are correlated with increased use of physical punishment. In the intervention group, there was a 2.7-point decrease in the ATS score at follow-up compared with baseline (P = 0.01). There was no decrease in the ATS in the control group. Brief interventions may shift parental attitudes toward using less physical punishment and have implications for improving anticipatory guidance within primary care and early education.