α‐Linolenic Acid Dietary Deficiency Alters Age‐Related Changes of Dopaminergic and Serotoninergic Neurotransmission in the Rat Frontal Cortex

TLDR

The study investigated how α‑linolenic acid deficiency affects dopaminergic and serotoninergic neurotransmission in the frontal cortex, striatum, and cerebellum of male rats at ages 2, 6, 12, and 24 months. Male rats were fed a diet deficient in α‑linolenic acid and examined across four age groups, measuring fatty acid composition, receptor densities, neurotransmitter levels, and monoamine oxidase activities in the frontal cortex, striatum, and cerebellum. Deficiency caused a severe drop in 22:6n‑3 fatty acids and a compensatory rise in n‑6 fatty acids, with partial recovery between 2 and 12 months; in the frontal cortex it led to a 40–75% reduction in endogenous dopamine, a 10% decrease in D2 receptor density, and an 18–46% increase in 5‑HT2 receptor density, while aging alone affected monoamine systems in striatum and cerebellum regardless of diet.

Abstract

Abstract: The effects of α‐linolenic acid diet deficiency on rat dopaminergic and serotoninergic neurotransmission systems were investigated in the frontal cortex, striatum, and cerebellum of male rats 2, 6, 12, and 24 months of age. The diet deficiency induced a severe decrease in the 22:6n‐3 fatty acid levels in all regions and a compensatory increase in n‐6 fatty acid levels. A recovery in the levels of 22:6n‐3 was observed in deficient rats between 2 and 12 months of age; however, this recovery was lower in frontal cortex than in striatum and cerebellum. In the striatum and the cerebellum, dopaminergic and serotoninergic receptor densities and endogenous dopamine and serotonin levels were affected by aging regardless of the diet. In contrast, a 40–75% lower level of endogenous dopamine in the frontal cortex occurred in deficient rats according to age. The deficiency also induced an 18–46% increase in serotonin 5‐HT 2 receptor density in the frontal cortex during aging, without variation in endogenous serotonin level, and a 10% reduction in density of dopaminergic D 2 receptors. Monoamine oxidase‐A and ‐B activities showed specific age‐related variations but regardless of the diet. Our results suggest that a chronically α‐linolenic‐deficient diet specifically affects the monoaminergic systems in the frontal cortex.