Distinct α subunit variations of the hypothalamic GABA_Areceptor triplets (αβγ) are linked to hibernating state in hamsters

• Main Authors: Alò Raffaella, Avolio Ennio, Di Vito Anna, Carelli Antonio, Facciolo Rosa, Canonaco Marcello
• Format: Article
• Language: English
• Published: BMC 2010-09-01
• Series: BMC Neuroscience
• Online Access: http://www.biomedcentral.com/1471-2202/11/111

<p>Abstract</p> <p>Background</p> <p>The structural arrangement of the γ-aminobutyric acid type A receptor (GABA_AR) is known to be crucial for the maintenance of cerebral-dependent homeostatic mechanisms during the promotion of highly adaptive neurophysiological events of the permissive hibernating rodent, i.e the Syrian golden hamster. In this study, <it>in vitro </it>quantitative autoradiography and <it>in situ </it>hybridization were assessed in major hypothalamic nuclei. Reverse Transcription Reaction-Polymerase chain reaction (RT-PCR) tests were performed for specific GABA_AR receptor subunit gene primers synthases of non-hibernating (NHIB) and hibernating (HIB) hamsters. Attempts were made to identify the type of αβγ subunit combinations operating during the switching ON/OFF of neuronal activities in some hypothalamic nuclei of hibernators.</p> <p>Results</p> <p>Both autoradiography and molecular analysis supplied distinct expression patterns of all α subunits considered as shown by a strong (p < 0.01) prevalence of α₁ratio (over total α subunits considered in the present study) in the medial preoptic area (MPOA) and arcuate nucleus (Arc) of NHIBs with respect to HIBs. At the same time α₂subunit levels proved to be typical of periventricular nucleus (Pe) and Arc of HIB, while strong α₄expression levels were detected during awakening state in the key circadian hypothalamic station, i.e. the suprachiasmatic nucleus (Sch; 60%). Regarding the other two subunits (β and γ), elevated β₃and γ₃mRNAs levels mostly characterized MPOA of HIBs, while prevalently elevated expression concentrations of the same subunits were also typical of Sch, even though this time during the awakening state. In the case of Arc, notably elevated levels were obtained for β₃and γ₂during hibernating conditions.</p> <p>Conclusion</p> <p>We conclude that different αβγ subunits are operating as major elements either at the onset of torpor or during induction of the arousal state in the Syrian golden hamster. The identification of a brain regional distribution pattern of distinct GABA_AR subunit combinations may prove to be very useful for highlighting GABAergic mechanisms functioning at least during the different physiological states of hibernators and this may have interesting therapeutic bearings on neurological sleeping disorders.</p>