Fatty Acid Metabolism via CPT1A Supports Poll Gland Function and Rutting Activities in Male Bactrian Camels

TL;DR

This study shows that fatty acid metabolism, especially through CPT1A, supports poll gland function and rutting behaviors in male Bactrian camels during the breeding season.

Contribution

The study identifies CPT1A as a key driver of fatty acid oxidation in poll gland function during the rutting season in male Bactrian camels.

Findings

CPT1A is significantly upregulated in breeding season camels, linking fatty acid oxidation to reproductive activity.

Proteomic and metabolomic analyses reveal CPT1A's role in energy production and regulation of fatty acid metabolism.

Histological evidence shows increased mitochondrial activity and ATP production during the rutting season.

Abstract

The poll gland, a specialized tissue of male Bactrian camels, undergoes seasonal enlargement and marked metabolic activation during the rutting season. However, the metabolic mechanisms of the poll gland and its role in rutting activities and inducing estrus are still not fully understood. This study aimed to investigate the contribution of fatty acid metabolic pathways, specifically those mediated by carnitine palmitoyltransferase 1A (CPT1A), in poll gland activity during the breeding season; poll gland tissue, neck mane, and urine samples were systematically collected from healthy male Bactrian camels stratified into breeding and non-breeding season groups for integrated proteomic, metabolomic, and biochemical assays. Histological and immunohistochemical analyses revealed reduced adipocytes but elevated ATP production in rutting camels, suggesting increased mitochondrial activity and enhanced oxidative phosphorylation. Proteomic analyses identified 119 differentially expressed proteins (DEPs) linked to fatty acid metabolism, with CPT1A, a key regulator of mitochondrial fatty acid oxidation, emerging as a central hub. The Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis further confirmed enrichment in fatty acid biosynthesis, degradation, and PPAR/AMPK signaling. The metabolomic analysis identified 14 metabolites, including acetylcarnitine and glycine, that were closely correlated with CPT1A expression, suggesting their potential involvement in regulating fatty acid metabolism during the breeding season. Quantitative expression analyses revealed that CPT1A in glandular acini was significantly upregulated in the breeding group compared to the non-breeding group across all assays: qPCR (2.53-fold, p < 0.05), Western blot (3.5-fold, p < 0.05), and immunohistochemistry (1.5-fold, p < 0.05). This demonstrated that CPT1A-mediated fatty acid metabolism plays a pivotal role in energy provision for reproductive activities. The results suggested that CPT1A-mediated fatty acid oxidation sustains poll gland function and reproductive behaviors in male Bactrian camels. This study provided a theoretical basis for understanding the role of CPT1A-mediated fatty acid oxidation in maintaining poll gland function and supporting reproductive activities in male Bactrian camels.

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