ANA-12(Medical University of South Carolina)

Memory reconsolidation is a re-stabilization phase in which memory is gradually changed from unstable to stable. This process is critical because unstable memories can be subject to modification or erasure if the reconsolidation phase is disrupted within a 6 h time window. TrkB signaling pathway plays a key role in regulating neurogenesis, neuronal differentiation, maturation and survival. Numerous studies have reported that the TrkB signaling pathway participates in memory acquisition, consolidation and storage, although its role in memory reconsolidation is not fully understood. ANA-12, as a type of TrkB receptor inhibitor, can regulate various pain behaviors and attenuate propofol-induced apoptosis by blocking the TrkB signaling pathway. In this study, we investigated the effect of ANA-12 on memory reconsolidation in a novel object recognition (NOR) task. The results showed that ANA-12 injection immediately after the reactivation phase of the NOR task inhibited memory reconsolidation, whereas ANA-12 injection 6 h after the reactivation phase had no effect on memory performance. ANA-12 injection 24 h after the sample phase, with no subsequent reactivation phase, had no effect on memory performance. Transcriptome analysis demonstrated that ANA-12 administration significantly upregulated 347 genes and downregulated 79 genes in the hippocampus, compared to vehicle-treated animals. Those differentially expressed genes are involved in a wide range of functional pathways, including neuroinflammation, neurotransmitter synthesis, metabolism and transport, and long-term potentiation, which are all linked to memory impairment. These findings indicate that ANA-12-induced impaired memory reconsolidation is associated with changes in multiple signaling pathways.

To investigate the therapeutic potential of ANA-12 in restoring testicular health by modulating local neurochemical balance in adult rats of passive smoking, secondhand smoking or environmental tobacco smoke/nicotine exposure.

Preclinical rodent models mimicking a real-life human smoking scenario.

Post-acclimatization, adult male rats of 250-300 g body weight were randomized into passive smoking, oral nicotine, ANA-12 pre-treatment, and healthy unexposed controls.

Rats were exposed to passive smoking through a whole-body inhalation chamber and oral nicotine through gavage with/without intraperitoneal administration of ANA-12 at differential dosages prior to passive smoking/nicotine exposure for a period of 4- and 12-week studies.

Testes histopathology, DNA damage potency, and fertility indices alongside redox homeostasis and expressions of local neurotransmitter dopamine and its receptors D1 and D2, and neurotrophic factor, brain-derived neurotrophic factor (BDNF) and its receptor, tyrosine kinase beta (Trk-β) in testes, comet assay in whole blood, and serum cotinine levels.

Compared with the healthy unexposed controls, passive smoking and oral nicotine exposure dose- and time-dependently disrupt developing spermatogonia, spermatocytes, and spermatids of the seminiferous tubules and basement membrane; reduce sperm count with concomitant higher deoxyribonucleic acid (DNA) damage; and upregulate BDNF/Trk-β and dopamine/D1 expressions, as well as oxidative stress with subsequent antioxidant depletion in testes. In contrast, regardless of the duration of exposure, ANA-12 pre-treatment significantly restores germ cells of the seminiferous epithelium, improves spermatogenesis, downregulates aberrant local neurochemical systems, and maintains redox homeostasis in the testicular milieu. These results are in accordance with the whole blood DNA damage and serum cotinine levels, a biomarker of nicotine exposure.

The results offer a novel insight into therapeutic interventions for passive or secondhand smoking- or environmental tobacco smoke-induced male reproductive impairment via regulation of BDNF-dopaminergic signaling and antioxidant balance in testes by ANA-12, leading to improved fertility potential and overall testicular health, which could establish the modulation of the brain-testes axis, implicated in nicotine addiction. This study holds translational potential of ANA-12 for the management of smoking- or nicotine-related male infertility of individuals unable or unwilling to quit smoking.