Neuroadaptations of presynaptic and postsynaptic GABA_B receptor function in the paraventricular nucleus in response to chronic unpredictable stress

Abstract

These findings suggest that chronic stress impairs postsynaptic GABA receptor function but augments presynaptic GABA receptor function in controlling glutamatergic and GABAergic synaptic inputs in PVN-CRH neurons.

Balancing tonic and phasic inhibition in hypothalamic corticotropin‐releasing hormone neurons

“…) in both the pre‐ and the postsynaptic membranes (Gao et al . ). We applied the GABA B R antagonist CGP (2 μ m ) to test whether constitutive activity of GABA B Rs modulates I Phasic in PVN CRH neurons (Fig.…”

“…A recent study examining PVN CRH neurons in rats, however, was unable to replicate this, instead reporting GABA B R‐mediated suppression only after a chronic unpredictable mild stress paradigm (Gao et al . ). One explanation for the discrepancy may be attributed to the difference in the age of animals used in each study.…”

“…() (3–4 weeks); Gao et al . () used older rats (7–10 weeks) and the absence of GABA B effects may be due to the decrease in GABA B R expression in older rat hypothalamus (Bianchi et al . ).…”

“…; Gao et al . ). The recruitment of GABA B Rs, which are likely sensitive to GABA uptake, should decrease I Phasic , but whether GABA B Rs also impact I Tonic indirectly in PVN CRH neurons is not known.…”

“…GABA transporters (GATs) in astrocytes and neurons play a key role in constraining I Tonic in other cell populations in PVN (Park et al 2006(Park et al , 2009Pandit et al 2015). Additionally, presynaptic GABA B Rs, which decrease release probability (P r ) of GABA, are also present within the PVN (Liu et al 2006;Gao et al 2017). The recruitment of GABA B Rs, which are likely sensitive to GABA uptake, should decrease I Phasic , but whether GABA B Rs also impact I Tonic indirectly in PVN CRH neurons is not known.…”