Specific Na+ sensors are functionally expressed in a neuronal population of the median preoptic nucleus of the rat.
نویسندگان
چکیده
Whole-cell patch-clamp recordings were performed on acute brain slices of male rats to investigate the ability of the neurons of the median preoptic nucleus (MnPO) to detect fluctuation in extracellular osmolarity and sodium concentration ([Na+]out). Local application of hypotonic and hypertonic artificial CSF hyperpolarized and depolarized the neurons, respectively. Similar responses obtained under synaptic isolation (0.5 microM TTX) highlighted the intrinsic ability of the MnPO neurons to detect changes in extracellular osmolarity and [Na+]out. Manipulating extracellular osmolarity, [Na+]out, and [Cl-]out showed in an independent manner that the MnPO neurons responded to a change in [Na+]out exclusively. The specific Na+ response was voltage insensitive and depended on the driving force for Na+ ions, indicating that a sustained background Na+ permeability controlled the membrane potential of the MnPO neurons. This specific response was not reduced by Gd3+, amiloride, or benzamil, ruling out the participation of mechanosensitive cationic channels, specific epithelial Na+ channels, and Phe-Met-Arg-Phe-gated Na+ channels, respectively. Combination of in situ hybridization, using a riboprobe directed against the atypical Na+ channel (Na(X)), and immunohistochemistry, using an antibody against neuron-specific nuclei protein, revealed that a substantial population of MnPO neurons expressed the Na(X) channel, which was characterized recently as a concentration-sensitive Na+ channel. This study shows that a neuronal population of the MnPO acts as functional Na+ sensors and that the Na(X) channel might represent the molecular basis for the extracellular sodium level sensing in these neurons.
منابع مشابه
Neuronal sodium leak channel is responsible for the detection of sodium in the rat median preoptic nucleus.
Sodium (Na(+)) ions are of primary importance for hydromineral and cardiovascular homeostasis, and the level of Na(+) in the body fluid compartments [plasma and cerebrospinal fluid (CSF)] is precisely monitored in the hypothalamus. Glial cells seem to play a critical role in the mechanism of Na(+) detection. However, the precise role of neurons in the detection of extracellular Na(+) concentrat...
متن کاملIntrinsic properties of the sodium sensor neurons in the rat median preoptic nucleus.
The essential role of the median preoptic nucleus (MnPO) in the integration of chemosensory information associated with the hydromineral state of the rat relies on the presence of a unique population of sodium (Na+) sensor neurons. Little is known about the intrinsic properties of these neurons; therefore, we used whole cell recordings in acute brain slices to determine the electrical fingerpri...
متن کاملRegulation of central Na+ detection requires the cooperative action of the NaX channel and α1 Isoform of Na+/K+-ATPase in the Na+-sensor neuronal population.
The median preoptic nucleus (MnPO) holds a strategic position in the hypothalamus. It is adjacent to the third ventricle; hence, it can directly access the ionic composition of the CSF. MnPO neurons play a critical role in hydromineral homeostasis regulation by acting as central sensors of extracellular Na(+) concentration ([Na(+)](ext)). The mechanism underlying Na(+) sensing involves the atyp...
متن کاملPostnatal expression of EAAC1 and glutamate receptor subunits in vestibular nuclear neurons responsive to vertical linear acceleration
Both glutamate receptors and transporters are known to be important in the postsynaptic regulation of glutamate neurotransmission. However, the maturation profile of glutamate transporter EAAC1 and glutamate receptor subunits (NR1, NR2A and NR2B; and GluR 1-4) in functionally activated saccule-related vestibular nuclear neurons of postnatal rats remains unclear. In the present study, conscious ...
متن کاملPostnatal expression of EAAC1 and glutamate receptor subunits in vestibular nuclear neurons responsive to vertical linear acceleration
Both glutamate receptors and transporters are known to be important in the postsynaptic regulation of glutamate neurotransmission. However, the maturation profile of glutamate transporter EAAC1 and glutamate receptor subunits (NR1, NR2A and NR2B; and GluR 1-4) in functionally activated saccule-related vestibular nuclear neurons of postnatal rats remains unclear. In the present study, conscious ...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید
ثبت ناماگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید
ورودعنوان ژورنال:
- The Journal of neuroscience : the official journal of the Society for Neuroscience
دوره 24 16 شماره
صفحات -
تاریخ انتشار 2004