Activity and Coupling to Hippocampal Oscillations of Median Raphe GABAergic Cells in Awake Mice

Ascending serotonergic/glutamatergic projection from the median raphe region (MRR) to the hippocampal formation regulates both encoding and consolidation of memory and the oscillations associated with them. The firing of various types of MRR neurons exhibits rhythmic modulation coupled to hippocampal oscillatory activity. A possible intermediary between rhythm-generating forebrain regions and entrained ascending modulation may be the GABAergic circuit in the MRR, known to be targeted by a diverse array of top-down inputs. However, the activity of inhibitory MRR neurons in an awake animal is still largely unexplored. In this study, we utilized whole cell patch-clamp, single cell, and multichannel extracellular recordings of GABAergic and non-GABAergic MRR neurons in awake, head-fixed mice. First, we have demonstrated that glutamatergic and serotonergic neurons receive both transient, phasic, and sustained tonic inhibition. Then, we observed substantial heterogeneity of GABAergic firing patterns but a marked modulation of activity by brain states and fine timescale coupling of spiking to theta and ripple oscillations. We also uncovered a correlation between the preferred theta phase and the direction of activity change during ripples, suggesting the segregation of inhibitory neurons into functional groups. Finally, we could detect complementary alteration of non-GABAergic neurons’ ripple-coupled activity. Our findings support the assumption that the local inhibitory circuit in the MRR may synchronize ascending serotonergic/glutamatergic modulation with hippocampal activity on a subsecond timescale.

Whole-brain connectivity atlas of glutamatergic and GABAergic neurons in the mouse dorsal and median raphe nuclei

The dorsal raphe nucleus (DR) and median raphe nucleus (MR) contain populations of glutamatergic and GABAergic neurons that regulate diverse behavioral functions. However, their whole-brain input-output circuits remain incompletely elucidated. We used viral tracing combined with fluorescence micro-optical sectioning tomography to generate a comprehensive whole-brain atlas of inputs and outputs of glutamatergic and GABAergic neurons in the DR and MR. We found that these neurons received inputs from similar upstream brain regions. The glutamatergic and GABAergic neurons in the same raphe nucleus had divergent projection patterns with differences in critical brain regions. Specifically, MR glutamatergic neurons projected to the lateral habenula through multiple pathways. Correlation and cluster analysis revealed that glutamatergic and GABAergic neurons in the same raphe nucleus received heterogeneous inputs and sent different collateral projections. This connectivity atlas further elucidates the anatomical architecture of the raphe nuclei, which could facilitate better understanding of their behavioral functions.

Single Median Raphe Scrotal incision Orchiopexy: A safe & feasible approach for fixation of Palpable Undescended testes

Background: We wish to share our outcome of single median raphe scrotal incision orchiopexy (SMRSO) regarding safety & feasibility of technique by evaluating ease of access, conversion rate, duration of surgery, success rate, complications, and the need for redo-surgery. Methods: We retrospectively analyzed data of 277 orchiopexies performed in our department on 224 patients operated on between June 2016 to June 2019. SMRSO was considered for palpable testes that can be brought to the upper limit of the scrotum under anesthesia. The conventional inguinoscrotal approach was used for high lying testes. A median raphe incision was made to access & mobilize the testis on either side, ligation of processus vaginalis performed, and the testes secured in the scrotal pouch. The approach was utilized for both unilateral and bilateral orchiopexies. Follow-up done at one week, one month & six months to evaluate the outcome. Results: A total of 277 orchiopexies were performed in 224 patients. 237 (86%) orchiopexies were via the median raphe scrotal approach in 184 patients. Out of these, 53 cases had bilateral orchiopexies. 30 (11%) performed via a conventional inguinoscrotal approach and 10 (4%) by laparoscopic approach. The mean duration of surgery for SMRSO was 24 minutes for unilateral and 42 minutes for bilateral cases. Immediate postoperative complications included scrotal hematoma in three (1.6%) cases, Hematoma of the abdominal wall in one case, and scrotal edema in 4 (2%) patients. All complications were treated conservatively & resolved. No wound infection or testicular atrophy was reported. Long-term complications included testicular ascend in three cases [1.6%]. Conclusion: Single-incision Median Raphe Scrotal orchiopexy is an attractive alternative to the standard inguinoscrotal orchiopexy for palpable low lying undescended testes with a better cosmetic outcome. doi: https://doi.org/10.12669/pjms.37.7.4261 How to cite this:Jan IA, Hassan M, Shalaan I, Alshehhi MA. Single Median Raphe Scrotal incision Orchiopexy: A safe & feasible approach for fixation of Palpable Undescended testes. Pak J Med Sci. 2021;37(7):---------. doi: https://doi.org/10.12669/pjms.37.7.4261 This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.