Serotonin (5-HT) Activation of Immortalized Hypothalamic Neuronal Cells Through the 5-HT1B Serotonin Receptor

Abstract

Serotonin [or 5-hydroxytryptamine or (5-HT)] has been implicated as a key modulator in energy homeostasis and a primary focus in the treatment of obesity. There is growing evidence that 5-HT, acting through the 5-HT 1B receptor (5-HT(1B)R) in the paraventricular nucleus of the hypothalamus (PVN), is important to this regulation. However, there is some contention as to whether 5-HT(1B)R action occurs directly on PVN neurons or indirectly via inhibitory inputs into the PVN. To address these questions, we used a novel clonal, hypothalamic neuronal cell model, adult mouse hypothalamic-2/30 (mHypoA-2/30), expressing a PVN-specific marker, single-minded homolog 1, as well as a complement of PVN neuropeptides, including TRH, vasopressin, ghrelin, nucleobindin-2, and galanin. Adult mouse hypothalamic-2/30 neurons were also found to express the 5-HT(1B)R and 5-HT 6 receptor, but not 2C, all previously linked to feeding regulation. Direct serotonergic stimulation (100 nm to 10 μm) of these neurons resulted in dose-dependent cFos activation. 5-HT (10 μm) suppressed forskolin-induced cAMP levels and induced a rise in intracellular Ca(2+) through ER Ca(2+) release, effects that were mimicked by the 5-HT(1B)R agonists, CGS12066B and CP93129, and that were attenuated in the presence of the 5-HT(1B)R-specific inhibitors, GR55562 and isamoltane hemifumarate. Modest transcriptional changes in ghrelin and nucleobindin-2 were also observed in response to 100 nm and 10 μm 5-HT, respectively. These findings support the model wherein 5-HT action through the 1B receptor subtype occurs directly on PVN neurons, leading to potential modification of neuronal transcriptional and secretory machinery.

Probable involvement of p11 with interferon alpha induced depression

“…Several studies have demonstrated that both 5-HTR1b and 5-HTR4 are critical for the initiation of depression. In the pre-synapses, 5-HTR1b acts as an autoreceptor to inhibit the release of serotonin 56 . Cai et al demonstrate that the activation of 5-HTR1b in post-synapse facilitates excitatory synaptic transmission, which is associated with depression 25 .…”

Roles for the Endoplasmic Reticulum in Regulation of Neuronal Calcium Homeostasis

“…Depletion of ER Ca 2+ stores by application of the SERCA inhibitor, thapsigargin, in cortical, hippocampal, and other neurons leads to the dramatic and rapid increase in the transcription of the immediate early genes encoding c-Fos and Homer-1a [73,74]. Stimulation of ER Ca 2+ release in hypothalamic neurons following application of serotonin also results in c-Fos induction via a process requiring ER Ca 2+ release through IP 3 Rs [75,76]. The relationship between c-Fos induction and ER Ca 2+ release reinforces the role for the latter in synaptic plasticity.…”

CRH-R2 signalling modulates feeding and circadian gene expression in hypothalamic mHypoA-2/30 neurons

“…The adult mouse derived hypothalamic neuronal cell line mHypoA-2/30 (CELLutions Biosystems Inc, Toronto, Canada), was used as an experimental model. These cells possess neuron-specific markers and function as effective models to study neuroendocrine signalling at the cellular level ( 24 ). Cells were grown in 6 well plates (Corning life Sciences, Flintshire, UK) with high glucose (HG) Dulbecco’s Modified Eagle’s Medium (DMEM, 4500 mg/L, Sigma-Aldrich, Dorset, UK) supplemented with 5% fetal bovine serum (FBS, Gibco, Paisley UK) and 1% penicillin-streptomycin (Biochrome AG, Berlin, Germany) maintained at 37°C and 5% CO2 until 90% confluency.…”