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Spinal lamina II (substantia gelatinosa, SG) neurons integrate nociceptive information from the primary afferents and are classified according to electrophysiological (tonic firing, delayed firing, single spike, initial burst, phasic firing, gap firing and reluctant firing) or morphological (islet, central, vertical, radial and unclassified) criteria. T-type calcium (Cav3) channels play an essential role in the central mechanism of pathological pain, but the electrophysiological properties and the cell-type specific distribution of T-type channels in SG neurons have not been fully elucidated. To investigate the electrophysiological and morphological features of T-type channel-expressing or -lacking neurons, voltage- and current-clamp recordings were performed on either transverse or parasagittal spinal cord slices. Recording made in transverse spinal cord slices showed that an inward current (IT) was observed in 44.5% of the SG neurons that was fully blocked by Ni2+ and TTA-A2. The amplitude of IT depended on the magnitude and the duration of hyperpolarization pre-pulse. The voltage for eliciting and maximizing IT were −70 mV and −35 mV, respectively. In addition, we found that most of the IT-expressing neurons are tonic firing neurons and exhibit more negative action potential (AP) threshold and smaller difference of AP threshold and resting membrane potential (RMP) than those neurons lacking IT. Consistently, a specific T-type calcium channel blocker TTA-P2 increased the AP threshold and enlarged the difference between AP threshold and membrane potential (Ihold = 0). Meanwhile, the morphological analysis indicated that most of the IT-expressing neurons are islet neurons. In conclusion, we identify a cell-type specific distribution and the function of T-type channels in SG neurons. These findings might provide new insights into the mechanisms underlying the contribution of T-type channels in sensory transmission.

Background: There is an emerging literature on the mental health of both pre-and post-partum mothers during the coronavirus disease 2019 (COVID-19) pandemic.Methods: As of April 1, 2020, 23 mothers confirmed with COVID-19, 15 mothers suspected with COVID-19 but with negative polymerase chain reaction tests, and 33 mothers without COVID-19 (Control Group) were recruited for a study from Hubei Province in China. The Maternal Postnatal Attachment Scale (MPAS), the Zung Self-rating Anxiety Scale, and the Zung Self-rating Depression Scale were applied to investigate the attachment of mothers to their neonates and the postpartum mental health of mothers within the first 3 months after delivery (between 20 to 89 days).Results: The period of mother-child separation among the confirmed group (33.9±20.9 days) was significantly longer than that of suspected group (16.7±12.2 days) and control group (10.7±8.4 days). The total score of the MPAS in mothers confirmed with COVID-19 (45.5±4.2) was significantly lower (indicating less mother-child attachment) than that in the suspected (50.5±4.7) and control (48.8±4.6) groups. A negative correlation was noted between the mother-child separation time and the MPAS scores, including the subscale scores of attachment (MPAS acore: Spearman's ρ =−0.33, 95% CI: −0.095 to −0.538, P=0.005; Subscale score of attachment: Spearman's ρ =−0.40, 95% CI: −0.163 to −0.592, P=0.001). The incidence of postpartum anxiety in the confirmed, suspected and control groups was 4.3%, 6.7% and 12.1%, respectively; and the incidence of postpartum depression was 39.1%, 33.3% and 30.3%, respectively. No significant difference was found with regards to maternal postpartum anxiety and depression among the three groups.Conclusions: Decreased mother-child attachment found among mothers confirmed with COVID-19, indicates that further intervention is needed to ensure mother-child interaction to appropriately develop attachment. Mother-child attachment experienced disruption due to prolonged mother-child separation necessitated by the COVID-19 management protocol, which needs to be revised to reduce prolonged mother-child separation. Additionally, mothers with and without COVID-19 suffered a high incidence of depression, which warrants further mental health investment for pregnant mothers during the COVID-19 pandemic.

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