In the present study, the responses of inhibitory gustatory neurons in the parabrachial nucleus (PBN) to four basic taste stimuli NaCl, HCl, quinine HCl (QHCl) and sucrose were examined using single-unit recording technique in anesthetized rats. A total of 18 inhibitory taste neurons in the PBN were obtained. Spontaneous firing rates of these inhibitory neurons were 0.2-5.5 Hz with mean firing rate of (2.15+/-0.31) Hz. Most of the neurons responded to more than one of the basic taste qualities. The inhibitory responses to taste occurred quickly and lasted 5-80 s in different PBN neurons. According to the responsive characteristics to the four basic taste stimuli, the neurons could be classified as NaCl-best (n=8), HCl-best (n=3), QHCl-best (n=3), and sucrose-best (n=4). The breadth of tuning of NaCl-best neurons was the highest (0.945). Inhibitory responsive neurons had feeble discrimination among sapid stimuli or aversive stimuli. These results suggest that there exist inhibitory taste neurons in the PBN. These neurons may play some useful roles in precise transmission of taste information and the taste coding for hedonic and aversive tastes.
Animals ; Male ; Neural Inhibition ; physiology ; Neurons ; physiology ; Pons ; physiology ; Rats ; Rats, Sprague-Dawley ; Taste ; physiology

OBJECTIVETo establishing the cochlea slice technique and infrared visual slice patch clamp method in order to observe the electrophysiological characteristics of rat spiral ganglion neurons (SGN) METHODS: SD rats were divided into three groups according to postnatal days old (0-2 d, 3-6 d and 7-14 d). Making slice of SD rat cochlear quickly, using infrared differential interference contrast (IR-DIC) technique, together with slice patch clamp, the electrophysiological characteristics of rat spiral ganglion neurons were observed, and factors which affected the quality of cochlear slice and recording of patch clamp were analyzed.

RESULTSThe success rate of 3-6 days SD was the highest, and 2-4 pieces of slice could be made from each cochlea. Cochlea connecting with partial skull and integrity of cochlear hull were the key for making slice, and the angle of modiolus axis should be adjusted to be parallel to the knife and the preparing time should be shorter. The SGN cell of good condition could be easily found and the seal test became easier with the help of infrared visual slice patch clamp method. The rest membrane potential was (-45.6 +/- 5.3) mV (x +/- s, n=52) and the current of Na+ and K+ could be activated.

CONCLUSIONSCochlear slice technique can retain structural integrity, cell viability and their association in cochlea, which suggest that this technique provides carrier for electrophysiological study of rat spiral ganglion neurons, and patch clamp with infrared videomicroscopy method can be used to make direct real-time observation in electrophysiological experiments of SGN, which can provide important technique support and reference for deep study of electrophysiological characteristics of SGN and auditory neurotransmission in cochlea.

Animals ; Cochlea ; physiology ; Microtomy ; Neurons ; physiology ; Patch-Clamp Techniques ; Rats ; Rats, Sprague-Dawley ; Spiral Ganglion ; physiology

Animals ; Electric Stimulation ; Hippocampus ; physiology ; Male ; Nerve Endings ; physiology ; Rats ; Rats, Sprague-Dawley ; Vagus Nerve ; physiology

Animals ; Calcitonin Gene-Related Peptide ; physiology ; Heart ; physiology ; Male ; Physical Exertion ; physiology ; Rats ; Rats, Sprague-Dawley

BACKGROUNDAs the widespread use of electric devices in modern life, human are exposed to extremely low frequency magnetic fields (ELF MF) much more frequently than ever. Over the past decades, a substantial number of epidemiological and experimental studies have demonstrated that ELF MF (50 Hz) exposure is associated with increased risk of various health effects. The present study examined the effects of chronic exposure to ELF MF on anxiety level and spatial memory of adult rats.

METHODSThe 50-Hz ELF MF was used during the whole experimental procedures and the value of magnetic field (MF) was set to 2 mT. Adult rats were divided randomly to control, MF 1 hour and MF 4 hours group. Anxiety-related behaviors were examined in the open field test and the elevated plus maze; changes in spatial learning and memory were determined in Morris water maze after 4 weeks of daily exposure.

RESULTSRats in MF 4 hours group had increased anxiety-like behaviors with unaltered locomotor activity. In the Morris water maze test, rats had reduced latency to find the hidden platform and improved long-term memory of former location of platform without changes in short-term memory and locomotor activity.

CONCLUSIONChronic ELF MF exposure has anxiogenic effect on rats, and the promoting effects on spatial learning and long-term retention of spatial memory.

Animals ; Anxiety ; physiopathology ; Electromagnetic Fields ; Male ; Maze Learning ; physiology ; Memory ; physiology ; Rats ; Rats, Sprague-Dawley

Animals ; Environment ; Female ; Male ; Maze Learning ; physiology ; Memory ; physiology ; Microarray Analysis ; Rats ; Rats, Sprague-Dawley ; Weaning

OBJECTIVETo examine the effect of docosahexaenoic acid (DHA) deficiency in brain on spatial learning and memory in rats.

METHODSSprague Dawley rats were fed with an n-3 fatty acid deficient diet for two generations to induce DHA depletion in brain. DHA in seven brain regions was analyzed using the gas-liquid chromatography. Morris water maze (MWM) was employed as an assessing index of spatial learning and memory in the n-3 fatty acid deficient adult rats of second generation.

RESULTSFeeding an n-3 deficient diet for two generations depleted DHA differently by 39%-63% in the seven brain regions including cerebellum, medulla, hypothalamus, striatum, hippocampus, cortex and midbrain. The MWM test showed that the n-3 deficient rats took a longer time and swam a longer distance to find the escape platform than the n-3 Adq group.

CONCLUSIONThe spatial learning and memory in adult rats are partially impaired by brain DHA depletion.

Animals ; Brain ; metabolism ; Docosahexaenoic Acids ; metabolism ; Maze Learning ; physiology ; Memory ; physiology ; Rats ; Rats, Sprague-Dawley

Animals ; Electric Stimulation ; Neurons ; pathology ; physiology ; Pain Threshold ; Rats ; Rats, Sprague-Dawley ; Red Nucleus ; pathology ; physiology

Animals ; Evoked Potentials, Motor ; physiology ; Male ; Rats ; Rats, Sprague-Dawley ; Signal Transduction ; Spinal Cord ; physiology

OBJECTIVETo observe the effects of repeated + Gz exposures on the apoptosis of myocyte in rats.

METHODSTwelve male Sprague-Dawley rats were randomly divided into three groups: Control group, + 6Gz group and + 10Gz group. The rats of + Gz groups were exposed to + 6Gz for 3 min, + 10Gz for 3 min respectively, 1 b/d, 1 week. Four control rats were kept at the Earth gravity (1G) in the room with the centrifuge. All animals were anaesthetized and anatomies 1 day after the last exposure. Ventricular myocardium was studied by electron microscopy and terminal deoxynucleotide transferase-mediated dUTP nick end labeling (TUNEL) method.

RESULTSThe apoptosis of myocyte in control group and + 6Gz group were scarcely observed by electron microscopy, while heterochromatin concentration and margination were observed in + 10Gz group. The apoptotic index of myocardium increased significantly in + 6Gz and + 10Gz group compared with that of the control group (P < 0.05) and showed the largest value in the + 10Gz group (P < 0.05).

CONCLUSIONRepeated + Gz exposures may induce apoptosis in myocyte, and the number of apoptosis in myocyte increases gradually with the increase of G value.

Acceleration ; Animals ; Apoptosis ; physiology ; Male ; Myocardium ; cytology ; Myocytes, Cardiac ; physiology ; Rats ; Rats, Sprague-Dawley