Neurogenic and Neuroendocrine Effects of Goldfish Pheromones

TLDR

Goldfish use reproductive hormones as endocrine signals and pheromones to coordinate spawning behavior among conspecifics. This study examined how two pheromonal hormones, prostaglandin F₂α and 17α,20β‑dihydroxy‑4‑pregnen‑3‑one, influence neurogenesis, neurotransmission, neuronal activity, and plasma androstenedione levels. The authors assessed neurogenesis, neurotransmission, neuronal activity, and AD levels in male and female goldfish exposed to waterborne PGF₂α or 17,20β‑P. PGF₂α increased diencephalic cell division, upregulated GnRH and ChAT transcripts, and promoted brain plasticity linked to spawning, whereas 17,20β‑P raised male plasma AD and induced androgen receptor and cGnRH‑II transcripts in female cerebellum, indicating distinct neuroendocrine pathways and establishing PGF₂α as the first pheromone linked to vertebrate neurogenesis.

Abstract

Goldfish ( Carassius auratus ) use reproductive hormones as endocrine signals to synchronize sexual behavior with gamete maturation and as exogenous signals (pheromones) to mediate spawning interactions between conspecifics. We examined the differential effects of two hormonal pheromones, prostaglandin F 2α (PGF 2α ) and 17α,20β-dihydroxy-4-pregnen-3-one (17,20β-P) on neurogenesis, neurotransmission, and neuronal activities, and on plasma androstenedione (AD) levels. Exposure to waterborne PGF 2α induced a multitude of changes in male goldfish brain. Histological examination indicated an increase in the number of dividing cells in male diencephalon ( p < 0.05, Kruskal–Wallis test). Real-time quantitative PCR tests showed elevated levels of transcripts for the salmon gonadotropin-releasing hormone (GnRH) in the male telencephalon and cerebellum ( p < 0.005, one-way ANOVA) and for ChAT (choline acetyltransferase) in the male vagal lobe and the brainstem underneath the vagal lobe ( p < 0.05, one-way ANOVA). Therefore, PGF 2α seemed to modulate male brain plasticity that coincided with behavioral changes during spawning season. Exposure to waterborne 17,20β-P, however, increased circulatory levels of immunoreactive AD in males and the transcripts of androgen receptor and cGnRH-II (chicken-II GnRH) in the female cerebellum ( p < 0.05, one-way ANOVA). PGF 2α and 17,20β-P thereby seemed to act through distinct pathways to elicit different responses in the neuroendocrine system. This is the first finding that links a specific pheromone molecule (PGF 2α ) to neurogenesis in a vertebrate animal.