Cortical Brain Injury Causes Retrograde Degeneration of Afferent Basal Forebrain Cholinergic Neurons via the p75NTR

Traumatic brain injury (TBI) elicits neuronal loss at the site of injury and progressive neuronal loss in the penumbra. However, the consequences of TBI on afferent neurons projecting to the injured tissue from distal locations is unknown. Basal forebrain cholinergic neurons (BFCNs) extend long projections to multiple brain regions including the cortex, regulate many cognitive functions, and are compromised in numerous neurodegenerative disorders. To determine the consequence of cortical injury on these afferent neurons, we used the fluid percussion injury model of traumatic brain injury and assessed the effects on BFCN survival and axon integrity in male and female mice. Survival or death of BF neurons can be regulated by neurotrophins or proneurotrophins, respectively. The injury elicited an induction of proNGF and proBDNF in the cortex and a loss of BFCNs ipsilateral to the injury compared with sham uninjured mice. The p75NTR knock-out mice did not show loss of BFCN neurons, indicating a retrograde degenerative effect of the cortical injury on the afferent BFCNs mediated through p75NTR. In contrast, locus ceruleus neurons, which also project throughout the cortex, were unaffected by the injury, suggesting specificity in retrograde degeneration after cortical TBI. Proneurotrophins (proNTs) provided directly to basal forebrain axons in microfluidic cultures triggered retrograde axonal degeneration and cell death, which did not occur in the absence of p75NTR. This study shows that after traumatic brain injury, proNTs induced in the injured cortex promote BFCN axonal degeneration and retrograde neuron loss through p75NTR.

Excess cerebellar granule neurons induced by the absence of p75NTR during development elicit social behavior deficits in mice

Introduction

Recently, the cerebellum has been implicated with non-motor functions, including cognitive and emotional behavior. Anatomical and functional studies demonstrate bidirectional cerebellar connections with brain regions involved in social cognition. Cerebellar developmental abnormalities and injury are often associated with several psychiatric and mental disorders including autism spectrum disorders and anxiety. The cerebellar granule neurons (CGN) are essential for cerebellar function since they provide sensorimotor, proprioceptive, and contextual information to Purkinje cells to modify behavior in different contexts. Therefore, alterations to the CGN population are likely to compromise cerebellar processing and function. Previously we demonstrated that the p75 neurotrophin receptor (p75NTR) was fundamental for the development of the CGN. In the absence of p75NTR, we observed increased proliferation of the granule cell precursors (GCPs), followed by increased GCP migration toward the internal granule layer. The excess granule cells were incorporated into the cerebellar network, inducing alterations in cerebellar circuit processing.

Methods

In the present study, we used two conditional mouse lines to specifically delete the expression of p75NTR in CGN. In both mouse lines, deletion of the target gene was under the control of the transcription factor Atoh-1 promotor, however, one of the lines was also tamoxifen-inducible.

Results

We observed a loss of p75NTR expression from the GCPs in all cerebellar lobes. Compared to control animals, both mouse lines exhibited a reduced preference for social interactions when presented with a choice to interact with a mouse or an object. Open-field locomotor behavior and operant reward learning were unaffected in both lines. Lack of preference for social novelty and increased anxiety-related behavior was present in mice with constitutive p75NTR deletion; however, these effects were not present in the tamoxifen-inducible mice with p75NTR deletion that more specifically targeted the GCPs.

Discussion

Our findings demonstrate that alterations to CGN development by loss of p75NTR alter social behavior, and contribute to the increasing evidence that the cerebellum plays a role in non-motor-related behaviors, including social behavior.

Role of 'krishna tila' and 'arkapushpa taila' uttarbasti in the management of artavakshaya

Ayurvedic classics give importance to Shuddha Artava and mention that Artavadushti is one of the causative factors for infertility. Artavakshaya is not separately described as disease any where in Ayurvedic classics, of course, this doesn't desecrate Artavakshaya. Because, Acharya Charaka has quoted in Charaka Nidana Sthana, first chapter, that symptoms of a disease themselves also constitute as a disease. But sometime, because of their subordinate nature they are only symptoms and not disease. This quotation substantiates the stand of taking 'Artavakshaya' as disease in the present studies. There are many processes and methods available in Ayurvedic classics to alleviate Artavakshya. But it is yet, the on going research to find out a method of treatment, which is nearer to procurance of permanent cure without side effects. It is well known that Ayurvedic classics emphasize on both Shodhana and Shamana therapy. Since Vata plays key role in Yoniroga, Uttarbasti, being Vata shamana, is a specific treatment in diseased condition of Yoni. As Shamana therapy Kwatha preparation choose to evaluate its efficacy. In the present study total 37 patients were registered, out of them 6 patients were discontinued. One group of patients was administered Arkapushpa Taila Uttarbasti and Krishna Tila Kwatha simultaneously. It gave more significant result. Krishna Tila Kwatha was administered orally in other group. Placebo wheat powder was administered orally in third group. Uttarbasti and Kwatha were found highly effective when administered simultaneously.