Electrophysiological properties of thermosensitive neurons in slices of rat lateral parabrachial nucleus.

Both warm- and cold-sensitive neurons are found in the lateral parabrachial nucleus (LPB), a crucial relay for skin temperature information from the spinal cord to the preoptic area. The aims of this study were to investigate the electrophysiological properties of temperature-sensitive and -insensitive neurons in brain slices, and elucidate the basic mechanisms underlying the thermosensitivity of rat LPB neurons. In warm-sensitive neurons, temperature exerted no significant effects on resting membrane potential (RMP), threshold potential, and amplitude of the afterhyperpolarizing potential. However, warming significantly increased the prepotential rates of depolarization and the inactivation rates of potassium A current (IA) in warm-sensitive neurons, which in turn shortened their interspike interval and elevated the firing rate. In contrast, temperature had no significant effects on the depolarizing prepotentials and inactivation rate of IA in temperature-insensitive neurons. Besides, in cold-sensitive neurons, cooling and warming produced membrane depolarization and hyperpolarization, respectively, and there was a strong correlation between firing rate and membrane potential thermosensitivity. Nevertheless, temperature exhibited no significant effect on the depolarizing prepotential of cold-sensitive neurons. These results suggest that LPB neuronal warm sensitivity may reside in the temperature-dependent prepotentials and IA, while neuronal cold sensitivity might be mainly due to heat-induced changes in RMP.

Primary hepatic pregnancy: a case report with a history of cesarean section and oral contraceptives, with review of literature.

Primary hepatic pregnancy is an extremely rare event which is difficult to diagnose due to its unusual location; moreover the potential mortality rate is five to seven times higher than the rate found in other ectopic pregnancies. We report a case of primary hepatic pregnancy in a 23-year-old woman, who presented with a history of one cesarean section and had taken oral contraceptives within half a year prior to her presentation. Interestingly this patient has no history of amenorrhoea, and no clinical symptoms of chills, fever, nausea, vomiting and diarrhea. Imaging findings showed an abnormal mass on the lower part of the right lobe. The patient was misdiagnosed with a liver tumor prior to operation. Histopathologic examination found that chorionic villi with trophoblasts infiltrated the hepatic tissue. A few trophoblasts were detected in some hepatic veins. HCG immunostaining showed positive reactivity in the trophoblasts. We believe that some risk factors of primary hepatic pregnancy such as the history of cesarean section and oral contraceptive should be taken into serious consideration and raise the index of suspicion, especially in the women of reproductive age, with or without a history of amenorrhoea. Timely diagnosis should be made in order to avoid mortality from rupture of the gestational sac.