Characteristics of Electrical Synapses, C-terminals and Small-conductance Ca2+ activated Potassium Channels in the Sexually Dimorphic Cremaster Motor Nucleus in Spinal Cord of Mouse and Rat

Sexually dimorphic motoneurons (MNs) located in lower lumbar spinal cord are involved in mating and reproductive behaviours and are known to be coupled by electrical synapses. The cremaster motor nucleus in upper lumbar spinal cord has also been suggested to support physiological processes associated with sexual behaviours in addition to its thermoregulatory and protective role in maintaining testes integrity. Using immunofluorescence approaches, we investigated whether cremaster MNs also exhibit features reflecting their potential for electrical synaptic communication and examined some of their other synaptic characteristics. Both mice and rats displayed punctate immunolabelling of Cx36 associated with cremaster MNs, indicative of gap junction formation. Transgenic mice with enhanced green fluorescent protein (eGFP) reporter for connexin36 expression showed that subpopulations of cremaster MNs in both male and female mice express eGFP, with greater proportions of those in male mice. The eGFP+ MNs within the cremaster nucleus vs. eGFP- MNs inside and outside this nucleus displayed a 5-fold greater density of serotonergic innervation and exhibited a paucity of innervation by C-terminals arising from cholinergic V0c interneurons. All MNs within the cremaster motor nucleus displayed prominent patches of immunolabelling for SK3 (K+) channels around their periphery, suggestive of their identity as slow MNs, many though not all of which were in apposition to C-terminals. The results provide evidence for electrical coupling of a large proportion of cremaster MNs and suggest the existence of two populations of these MNs with possibly differential innervation of their peripheral target muscles serving different functions.

LRRTMs Organize Synapses through Differential Engagement of Neurexin and PTPσ

Presynaptic neurexins (Nrxs) and type IIa receptor-type protein tyrosine phosphatases (RPTPs) organize synapses through a network of postsynaptic ligands. We show that leucine-rich-repeat transmembrane neuronal proteins (LRRTMs) differentially engage the protein domains of Nrx but require its heparan sulfate (HS) modification to induce presynaptic differentiation. Binding to the HS of Nrx is sufficient for LRRTM3 and LRRTM4 to induce synaptogenesis. We identify mammalian Nrx1γ as a potent synapse organizer and reveal LRRTM4 as its postsynaptic ligand. Mice expressing a mutant form of LRRTM4 that cannot bind to HS show structural and functional deficits at dentate gyrus excitatory synapses. Through the HS of Nrx, LRRTMs also recruit PTPσ to induce presynaptic differentiation but function to varying degrees in its absence. PTPσ forms a robust complex with Nrx, revealing an unexpected interaction between the two presynaptic hubs. These findings underscore the complex interplay of synapse organizers in specifying the molecular logic of a neural circuit.

Study of Adherence Pattern of Antidepressants in Patients with Depression

Background Depression is one of the leading psychiatric disorders of the world affecting a person's mood, physical health and behavior. It is not permanent and is neither a character flaw nor a lack in discipline for a person to be ashamed of. It is a disorder that is reliably diagnosed and successfully treated. Antidepressants are the standard and the most efficacious approach to treating people with depression. However, adherence to treatment is necessary for achieving effectiveness. The result of nonadherence is severe and may cause therapeutic failure resulting in poor quality of life. Objective To determine the medication adherence pattern in patients with depression and assess the factors associated with non-adherence to the prescribed antidepressant therapy. Method Patients meeting the inclusion criteria who were diagnosed with depression were taken for the study. Informed consent was taken from the patients or from their relatives in case of their incapability. They were then interviewed using structured questionnaire. Result Among the 60 patients included in the study, 78% of them were females. Most of the patients 43% (n=26) were prescribed with atypical antidepressants. Less number (37%) of the patients were adherent to the antidepressant therapy. 68% of the females were non adherent. 82% of housewives were not adherent to therapy. Forgetfulness was the main reason for missing dose in majority (50%) of the nonadherent patients. Conclusion Majority of the patients with depression were non-adherent to medication. Forgetfulness was the major reason for missing dose in these patients.

A Prospective Study of Commonly Prescribed Drugs in the Management of Neuropathic Pain and its Medication Adherence Pattern

Background Neuropathic pain is one of the common complains of patients visiting neurology and orthopedic departments in hospitals. Management of neuropathic pain is difficult and is often symptomatic rather than being curative. Adherence to medication is necessary for pain management to be effective. However, there are various factors related to patient, physician, drug regimen and other socio-economic affecting adherence. Objective To study commonly prescribed drugs in neuropathic pain management and the medication adherence pattern including its associated factors. Method Patients already diagnosed as neuropathic pain were interviewed using structured questionnaire and data entered in Microsoft Office Excel 2007. Informed consent was taken from the patients. Result Among the 84 patients in the study, 69% were females. Majority 53.6% of patients had low back pain as cause of neuropathic pain. Anticonvulsants were mostly prescribed (75%) followed by non-steroidal anti-inflammatory drugs (52.4%) and Methylcobalamin (47.6%). More than 50% (n=49) patients were not adherent to the prescribed medication and majority (61.2%) of them were housewives. Significant association was observed between patient's adherence to gender, occupation, polypharmacy, drug regimen, cost and availability of medicine. Conclusion Anticonvulsants were commonly prescribed drugs in patients with neuropathic pain. Neuropathic pain was seen more in females with low back pain. Majority of patients were non-adherent and forgetfulness was the major reason for missing dose in them.