Key neuropeptide and neuroendocrine pathways of the optic lobe are affected by high temperatures in the female Octopus maya

This study investigated the neuroendocrine role of the optic lobe (OL) in Octopus maya females during reproduction. While previous neuroendocrine research in octopus has focused on the gonads, optic glands, olfactory lobes, and oviducal glands, the role of the OL remains less explored. A transcriptomic approach was used to compare gene expression in the OL across reproductive stages-mating, egg-laying, and senescence-and with other tissues. Additionally, mature females were exposed to a thermal challenge (TC), and their OL transcriptomes were compared to those maintained at optimal temperatures (24 °C). Compared to other octopus' tissues, the OL transcriptome was enriched with genes encoding neuropeptides, neuroendocrine proteins, and neurotransmitter-modifying enzymes, confirming its neuroendocrine functions. Notably, transcripts of the LWamide neuropeptide, which is involved in life-stage transitions, were exclusively detected in the OL. Genes from neuroendocrine and neuropeptide pathways exhibited stable expression patterns throughout the reproductive stages. However, the TC induced stage-specific changes in gene expression. For instance, at the mating stage, transcripts of FMRF-amide, buccalin, and neuropeptide prohormone-4 were upregulated. At the egg-laying stage, apoptotic transcripts were upregulated, while genes encoding the neuroendocrine protein 7B2 and multiple ATPases were downregulated. Finally, at the senescence stage, mitochondrial and metabolic transcripts were downregulated by the TC. Temperature-driven changes in gene expression during the mating and egg-laying stages could be linked to a decrease in the reproductive success of this octopus species. This study confirms the critical role of OL in neuropeptide and neuroendocrine pathways that regulate the physiology and reproduction of octopuses.