Developmental Hippocampal Neuroplasticity in a Model of Nicotine Replacement Therapy during Pregnancy and Breastfeeding

The influence of developmental nicotine exposure on the brain represents an important health topic in light of the popularity of nicotine replacement therapy (NRT) as a smoking cessation method during pregnancy.In this study, we used a model of NRT during pregnancy and breastfeeding to explore the consequences of chronic developmental nicotine exposure on cerebral neuroplasticity in the offspring. We focused on two dynamic lifelong phenomena in the dentate gyrus (DG) of the hippocampus that are highly sensitive to the environment: granule cell neurogenesis and long-term potentiation (LTP).Pregnant rats were implanted with osmotic mini-pumps delivering either nicotine or saline solutions. Plasma nicotine and metabolite levels were measured in dams and offspring. Corticosterone levels, DG neurogenesis (cell proliferation, survival and differentiation) and glutamatergic electrophysiological activity were measured in pups.Juvenile (P15) and adolescent (P41) offspring exposed to nicotine throughout prenatal and postnatal development displayed no significant alteration in DG neurogenesis compared to control offspring. However, NRT-like nicotine exposure significantly increased LTP in the DG of juvenile offspring as measured in vitro from hippocampal slices, suggesting that the mechanisms underlying nicotine-induced LTP enhancement previously described in adult rats are already functional in pups.These results indicate that synaptic plasticity is disrupted in offspring breastfed by dams passively exposed to nicotine in an NRT-like fashion

The Enlarged Translabyrinthine and Transapical Extension Type I Approach for Large Vestibular Schwannomas

To evaluate the results obtained by performing the enlarged translabyrinthine and transapical extension type I approaches for removal of large vestibular schwannomas and those with anterior extensions. An academic tertiary referral centre at Mumbai, India. Retrospective case review. 35 patients of vestibular schwannomas having size greater than 3 cm in extrameatal diameter with extension anterior to the internal auditory canal who underwent the enlarged translabyrinthine or transapical extension type I approach and with a minimum follow up of 1 year are considered. Other subjects who underwent translabyrinthine approach but did not fulfill the above criteria were excluded. Tumor was removed completely in 34 subjects (97.1%). Anatomic interruption of facial nerve occured in 4 cases (11.4%); 3 subjects underwent end to end anastomosis and 1 subject required a cable graft, these were done during the primary procedure itself. At 1 year follow up 28 subjects (80%) had good facial function (Grade I and II, House Brackmann Grading). Postoperative cerebrospinal fluid leak was encountered in 1 subject (2.9%). 34 subjects (97.1%) had a normal albeit slow gait by the sixth post-operative day. Complete tumor removal with a very low morbidity in our series suggest that the enlarged translabyrinthine and transapical extension type I approach offers excellent control of the neurovascular structures in the cerebellopontine angle as also of the large vestibular schwannoma itself aiding complete removal. It also offers the advantage of management of the interrupted facial nerve at the primary procedure itself since the proximal and distal segments are in the operative field