Cellular and Network Effects of Introducing Connexin-36 Expression in an Uncoupled Neuronal Population in the Mouse Hypothalamus
Year: 2026
Type: preprint
Abstract: Electrical synapses are prevalent throughout nervous systems, including the mammalian brain. Several lines of evidence implicate these gap junction connections in several important roles in neural networks. Yet, progress has been hampered by a shortage of experimental tools to investigate their function with sufficient precision. In an effort to address this deficit, we here take advantage of a curious species-difference in electrical coupling in tuberoinfundibular dopamine (TIDA) neurons of the rodent hypothalamus. In rats, these cells exhibit strong electrical coupling, generating stereotyped, slow oscillations that are synchronized across the population. In contrast, mouse TIDA neurons lack gap junctions and display diverse, faster, and asynchronous oscillations. Motivated by this natural discrepancy, we designed a gain-of-function strategy to induce localized and robust expression of the main pore-forming protein of neuronal gap junctions, connexin-36 (Cx36), in mouse TIDA neurons by viral vectors. This perturbation yielded electrical coupling that was weaker than the rat TIDA system, but on par with many other brain populations connected by gap junctions. Cx36 overexpression resulted in significantly increased auto- and cross-correlation, as well as augmented functional connectivity, in agreement with the induction of electrical synapses in the population. Yet, these measures were modest in comparison with rat TIDA neurons, and Cx36 overexpression failed to alter serum levels of the hormone prolactin, which is controlled by this neuroendocrine system. These findings highlight the potential and limitations of experimentally inducing electrical synapses in a natively uncoupled system, and suggest directions for future improvements. Significance statement Many neurons communicate by electrical synapses, in addition to classical chemical synapses. However, understanding of the properties and role of the former remains limited in the absence of sufficiently precise experimental tools. Here, we applied a novel strategy by attempting to convert a natural species difference in neuroendocrine dopamine (“TIDA”) neurons, which are strongly coupled in rats but completely lack electrical synapses in mice. By overexpressing the pore-forming protein, connexin-36, in mouse TIDA neurons, several measures of electrical coupling and synchronizing network effects were induced, albeit weakly. While network interactions were significantly altered by overexpression, overall circuit performance, reflected in target hormone levels, remained stable. These findings illustrate both the promise and current limitations of gain-of-function manipulations of electrical coupling.
Institution: Stockholm University
Language: English
Topic: Connexins and lens biology
Subfield: Molecular Biology
Domain: Life Sciences
Open Access status: green
Funders: Vetenskapsrådet, Stockholms Universitet
OpenAlex ID: W7214804646