The research, published in eNeuro, an open-access, peer-reviewed scientific journal published by the Society for Neuroscience, explores how nicotine influences key areas associated with reward and aversion, showcasing a nuanced relationship that varies based on dosage, sex and distinct brain regions. The medial habenula (MHb), a region known for regulating nicotine aversion, takes center stage in the study. Researchers discovered that MHb activity experiences fluctuations, either heightened or diminished, depending on factors such as the amount of nicotine consumed, dosage variations (with or without menthol), and the sex of the subject. Intriguingly, this modulation was not mirrored in reward centers like the ventral tegmental area, challenging previous assumptions about nicotine’s impact.

“This study demonstrates that the activity of crucial brain regions associated with nicotine dependence is altered in different ways based on nicotine dosage and sex,” said lead researcher Nathan Olszewski, a biomedical research doctoral student at Marshall University in the laboratory of Brandon J. Henderson, Ph.D. “Nicotine usage affects individuals uniquely, making it advisable for users to exercise caution.”

The study employed a vapor-inhalation model of nicotine self-administration in mice, utilizing nose poking to earn nicotine vapor deliveries. Employing patch-clamp electrophysiology, researchers elucidated changes in neuronal excitability in the medial habenula and ventral tegmental area based on nicotine dosage and sex. Fast-scan cyclic voltammetry was also used to assess changes in dopamine release dynamics in the nucleus accumbens.

“In our field, attention has predominantly focused on specific regions like the ventral tegmental area,” said Henderson, an associate professor of biomedical sciences at Marshall University. “This study underscores the necessity of exploring other brain areas controlling the negative aspects of nicotine exposure.”

The researchers aim to expand their investigation to other brain regions, particularly focusing on the interplay between the MHb and the interpeduncular nucleus (IPN). This circuit, known as the aversive pathway of nicotine usage, plays a crucial role in limiting nicotine intake and withdrawal symptoms. Future research will utilize electrophysiology, confocal microscopy and RNA-fluorescent in situ hybridization (FISH) to understand how nicotine alters the activity and expression of nicotinic acetylcholine receptors in this aversive circuit.

In addition to Olszewski and Henderson, Samuel Tetteh-Quarshie, another Ph.D. student in the Henderson laboratory, is a co-author on the study. This study was supported with grant funding (#DA050717 to Henderson) from the National Institute on Drug Abuse (NIDA).

Visible Changes in the Nervous System

A research team from Julius-Maximilians-Universität Würzburg (JMU) discovered this a few years ago. However, it was previously unknown where in the ants’ brains the magnetic information is processed. This has now changed: In a new study published in the journal PNAS — Proceedings of the National Academy of Sciences, the team shows that information about the Earth’s magnetic field is primarily processed in the ants’ internal compass, the so-called central complex, and in the mushroom bodies, the animals’ learning and memory centers.

Professor Wolfgang Rössler, holder of the Chair of Behavioral Physiology and Sociobiology at the University of Würzburg, Dr. Pauline Fleischmann, former scientist at the Chair of Behavioral Physiology and Sociobiology and now a member of the Neurosensorics/ Animal Navigation working group at the University of Oldenburg, and Dr. Robin Grob, who has since moved from Rössler’s chair to the Norwegian University of Science and Technology in Trondheim, were responsible for this study.

First Exploratory Walks for Calibration

“Before an ant leaves its underground nest for the first time and goes in search of food, it has to calibrate its navigation system,” says Pauline Fleischmann, explaining the background to the work. During so-called learning walks, the animals then explore the immediate surroundings around the nest entrance and repeatedly pirouette around their own body axis with short stops in between. During these pauses, they always look exactly back in the direction of the nest entrance, even though they cannot see it — a tiny hole in the ground.

Thanks to their field studies in southern Greece, where Cataglyphis ants are native, Fleischmann and her colleagues were able to prove that desert ants orient themselves to the Earth’s magnetic field during the learning walk phase. Pauline Fleischmann and Robin Grob were once again on site in Greece. This time, however, they not only investigated the ants’ orientation behavior while the magnetic field was being manipulated, but also looked for changes in the nervous system of Cataglyphis as an expression of the newly acquired experience.

A Faulty Magnetic Field Disrupts the Learning Process

The zoologists concentrated on young workers that had not yet undertaken any learning walks. The animals were only allowed to set off as part of the precisely planned experiments — sometimes under natural conditions, sometimes in a permanently manipulated magnetic field that, for example, displayed chaotic directions or did not allow horizontal orientation. With this faulty directional information, it was not suitable as a reliable reference system for the ants’ behavior to look back to the nest entrance during the learning walks.

The result: “Our neuroanatomical brain analyses show that ants exposed to an altered magnetic field have a smaller volume and fewer synaptic complexes in an area of the brain responsible for the integration of visual information and learning, the so-called mushroom body,” explain Fleischmann and Grob. In the central complex, the region of the ant’s brain in which spatial orientation is anchored, the same findings were observed under certain conditions.

The Number of Synaptic Connections Increases

Desert ants that were allowed to make their first excursions under natural conditions were clearly different. Their sensory experiences, a combination of information about the magnetic field, the position of the sun and the visual environment, triggered a learning process that was accompanied by structural changes in the neurons and an increase in synaptic connections in the aforementioned brain regions.

According to the scientists, this leads to the conclusion that magnetic information not only serves as a compass for navigation, but also as a global reference system that is crucial for the formation of spatial memory.

In Search of the Sensory Organ

The results of their experiments prove “that ants need a functioning magnetic compass during their learning walks in order to calibrate their visual compass and at the same time store images of the nest environment in their long-term memory,” as Pauline Fleischmann and Robin Grob say. At the same time, their research extends far beyond the field of compass calibration in ants. Wolfgang Rössler emphasizes that “the results provide valuable information on how multisensory stimuli can influence neuronal plasticity of brain circuits for navigation in a critical phase of brain maturation.”

In a next step, the team now wants to investigate in which sensory organ the desert ant receives the magnetic information and via which sensory pathways it is transmitted and processed. This has not yet been achieved with any animal species that orients itself to the Earth’s magnetic field. Due to their manageable and relatively small nervous system, insects, to which Cataglyphis belongs, offer a unique opportunity to investigate the neuronal basis of magnetic orientation at all levels.

The new research published in the Journal of Physiology conducted by an interdisciplinary consortium of clinicians and researchers led by University of Birmingham and collaborators in Germany.

The team found that male sex hormones, such as testosterone, also called androgenic anabolic steroids (AAS), which are misused for muscle building particularly among in young men can increase the risk of atrial fibrillation in individuals genetically predisposed to heart diseases.

Dr Laura Sommerfeld, Postdoctoral Researcher at the UKE Hamburg, who completed her PhD at the Institute of Cardiovascular Sciences at the University of Birmingham focusing on this work is lead author of the study.

Dr Sommerfeld said: “Our study can significantly contribute to understanding the impact on the heart health of young men who misuse anabolic steroids to increase muscle mass. Recent reports have shown that young men in particular are being targeted on social media such as TikTok being sold testosterone products, but we have shown how the misuse of steroids carries a specific risk that many people will not be aware of.”

Professor Larissa Fabritz, Chair of Inherited Cardiac Conditions at UKE Hamburg and Honorary Chair in the Institute of Cardiovascular Sciences at the University of Birmingham added:

“Heart muscle diseases like ARVC affect young, athletic individuals and can lead to life-threatening heart rhythm disturbances. Atrial fibrillation is a common condition in the general population. Elevated testosterone levels can result in an earlier onset of these diseases.”

The scientists examined potential effects on a condition called arrhythmogenic right ventricular cardiomyopathy (ARVC), which is genetically determined and primarily attributed to disruptions in the formation of cell connections critical for heart muscle stability.

The scientists initially confirmed, based on clinical patient data from UHB and elsewhere, that ARVC occurs more frequently and severely in men than in women. In laboratory experiments, they discovered that six weeks of AAS intake, combined with impaired cell connections, could lead to reduced sodium channel function in heart tissue and a slowing of signal conduction within the atria.

Dr Andrew Holmes, co-author and Assistant Professor in the Institute of Clinical Sciences at the University of Birmingham said:

“This work implies that young male individuals with key inherited genetic changes have a greater risk of developing electrical problems in the heart in response to anabolic steroid abuse.”

Many of these altered immune genes are the same ones that increase an individual’s risk for Alzheimer’s. Northwestern scientists theorize the cause could be a previous viral infection, environmental pollutants or other lifestyle factors and behaviors.

“It is possible that these findings implicate the peripheral immune response in Alzheimer’s disease risk,” said lead investigator David Gate, assistant professor of neurology at Northwestern University Feinberg School of Medicine. “We haven’t yet untangled whether these changes are reflective of brain pathology or whether they precipitate the disease.”

The study was published Feb. 9 in Neuron.

Previous research showed that many of the mutated genes putting a person at higher risk for Alzheimer’s are in the immune system. But scientists primarily studied the central immune system in the brain because Alzheimer’s is a brain disease. They have largely ignored the immune system in the blood, also known as the peripheral immune system.

Gate decided to study the blood. He and colleagues discovered every immune cell type in Alzheimer’s patients has epigenetic changes, indicated by open chromatin. Chromatin is the packaging of the DNA within cells. When chromatin is open — or exposed — the cells’ genome is vulnerable to alterations.

Then, Gate examined which genes are more open in these immune cells. He discovered that a receptor — CXCR3 — on the T cells was more exposed. Gate believes CXCR3 functions like an antenna on T cells that allows the cells to enter the brain. T cells do not normally enter the brain because they can cause inflammation.

“The brain is emitting a signal that it is damaged, and the T cells are homing to that signal by their antenna, CXCR3,” Gate said.

“T cells can be very toxic in the brain, but we also don’t know if these cells might be attempting to repair the damage in the brain,” Gate said.

Gate also discovered epigenetic changes in inflammatory proteins in white blood cells called monocytes.

“Altogether, these findings indicate that immune function in Alzheimer’s patients is significantly altered,” Gate said. “It could be that environmental factors, like pollutants, or infections that a person has in their lifetime cause these epigenetic changes.”

The findings revealed several genes that may be therapeutic targets for manipulating the peripheral immune system. Next steps in the research are preclinical studies using in vitro culture systems and animal models to test these targets.

Other Northwestern authors include Abhirami Ramakrishnan, Natalie Piehl, Brooke Simonton, Milan Parikh, Ziyang Zhang, Victoria Teregulova and Lynn van Olst.

The title of the article is “Epigenetic dysregulation in Alzheimer’s disease peripheral immunity.”

The research is supported by National Institute of Neurological Disorders and Stroke grant NS112458 and National Institute on Aging grant AG078713, both of the National Institutes of Health, Bright Focus Foundation, Alzheimer’s Association and Cure Alzheimer’s Fund.

Palaeontologists from the NHMW found snail shells of the superfamily Cerithioidea in Burgenland, Austria. The snails lived there twelve million years ago on the shores of a tropical sea. Professor Mathias Harzhauser at NHMW, who was involved in the discovery, explains: “It was unclear whether the patterns of reddish colour were from the original shell or were formed by later processes in the sediment.” Researchers at Göttingen University’s Geoscience Center solved the mystery. They analysed the pigments using Raman spectroscopy. This involves irradiating samples with laser light. The scattered light reflected from the sample can be used to clearly identify chemical compounds. They detected pigments in the fossilised shells that belong to the polyene group of chemicals. These are organic compounds that include the well-known “carotenoids,” which are responsible for producing the vibrant red, orange and yellow colours seen in birds’ feathers, carrots and egg yolks, for instance.

Dr Klaus Wolkenstein, who led the study and has been researching the chemistry of fossil pigments at Göttingen University for many years, explains: “Normally, after such a long period of time, the best we can hope for is that there are traces of degradation products of these chemicals. If degraded, however, these compounds would be devoid of colour. So, it was really surprising to discover these pigments, preserved almost intact, in fossils that are twelve million years old.”