Olfactory Epithelium Infection by SARS-CoV-2: Possible Neuroinflammatory Consequences of COVID-19.

Background: The loss of smell is a typical diagnostic symptom of coronavirus disease 2019 (COVID-19). This sensorial deprivation may be expressed as quantitative (anosmia or hyposmia) or qualitative (dysosmia) alterations as a consequence of anatomical disturbances of the nasal epithelium structure. The olfactory system sends direct neuronal connections to brain structures that are involved in emotional processing, including deep temporal nuclei.

Ketamine and fluoxetine exert similar actions on prelimbic and infralimbic responsivity to lateral septal nucleus stimulation in Wistar rats.

Ketamine is a dissociative anesthetic that has been proposed to be a useful alternative in cases of a poor response to other treatments in patients with depression. Remarkably, beneficial clinical actions of ketamine are detected once its psychotropic actions disappear. Therefore, clinical actions may occur independently of dose.

Prelimbic and infralimbic responsivity to amygdala input is modified by gonadal hormones in parallel to low anxiety-like behavior in ovariectomized rats.

Gonadal hormones may influence sexual activity by reducing anxiety. The basolateral amygdala (BLA) and prelimbic (PL) and infralimbic (IL) cortical regions comprise a loop that is related to fear, anxiety, and social behavior. In female ovariectomized rats, actions of estradiol, progesterone, and sequential estradiol and progesterone administration were explored in the open field test (OFT) and plus maze test (PMT) to evaluate signs of anxiety-like behavior.

Anxiety Constitutes an Early Sign of Acute Hypoglycemia.

Introduction: Research in humans has identified a link between hypoglycemia and anxiety. The present study examined anxiety-like behaviors in rats that were subjected to hypoglycemia that was produced by an acute injection of insulin. Healthy female Wistar rats were subjected to a battery of tests to explore anxiety (elevated plus maze) and locomotion (open field test).

Insulin and fluoxetine produce opposite actions on lateral septal nucleus-infralimbic region connection responsivity.

Some diabetes patients develop depression, the main treatment for which is antidepressants. Pharmacological interactions between insulin and antidepressants (e.g.

2-Heptanone reduces inhibitory control of the amygdala over the prelimbic region in rats.

Basolateral amygdala (BLA) nuclei and their reciprocal connections with prelimbic (PL) and infralimbic (IL) regions of the medial prefrontal cortex (mPFC) are involved in the regulation of fear. 2-Heptanone is released in urine in stressed rats, and the olfactory detection of this odor produces immediate avoidance and alarm reactions and modifies neuronal activity in limbic connections in non-stressed rats. If 2-heptanone acts as a danger signal, then long-lasting actions would be expected.

Putative Anti-Immobility Action of Acute Insulin Is Attributable to an Increase in Locomotor Activity in Healthy Wistar Rats.

Background/aims: Anti-immobility actions of insulin in diabetic rats that are subjected to the forced swim test (FST) have been reported. In this test, low doses of antidepressants exert actions after long-term treatment, without affecting locomotor activity in healthy rats. Few studies have compared acute and chronic actions of insulin with antidepressants in healthy rats.

Estrogen and progesterone priming induces lordosis in female rats by reversing the inhibitory influence of the infralimbic cortex on neuronal activity of the lateral septal nucleus.

The lateral septal nucleus (LSN) exerts inhibitory control over lordosis in female rats, but the influence of forebrain structures, such as prelimbic (PL) and infralimbic (IL) regions of the medial prefrontal cortex (mPFC), on LSN activity during sexual receptivity is unknown. We hypothesized that the neural responsivity of these connections may differ depending on sexual receptivity. Gonadally intact female Wistar rats received sequential priming injections of estradiol and progesterone (E2-P4).

Responsivity of lateral septum-mPFC connections in alloxan-induced hyperglycemia.

The lateral septal nucleus (LSN) is related to the actions of antidepressants, and the prelimbic cortex (PL) and infralimbic cortex (IL) modulate responses to fear. However, unknown is whether experimental diabetes that is induced by alloxan alters the responsivity of these regions. We used a method in which one forebrain region (LSN) was electrically stimulated while single-unit extracellular recordings were performed in another mPFC region (PL and IL).

Reciprocal interactions between the basolateral amygdala and infralimbic and prelimbic regions of the mPFC: Actions of diazepam.

The basolateral amygdala (BLA) and prelimbic (PL) and infralimbic (IL) cortices are interconnected structures that participate in the regulation of fear. Unknown are the reciprocal functional influence of these regions on neuronal responsivity and the action of an anxiolytic drug. We performed multiunit activity recordings from one neuronal pool while applying electrical stimulation to another neuronal pool.

Fluoxetine and stress inversely modify lateral septal nucleus-mpfc neuronal responsivity.

Several clinically effective antidepressants increase the neuronal firing rate in the lateral septal nucleus (LSN), a forebrain structure that is anatomically related to medial prefrontal cortex (mPFC) regions. mPFC function is related to depression and the regulation of fear. However, unknown is whether antidepressant treatment or chronic stress modifies the responsivity of neuronal LSN-mPFC connections.

An alarm pheromone reduces ventral tegmental area-nucleus accumbens shell responsivity.

2-Heptanone (methyl n-amyl ketone) is a ketone that produces alarm reactions in insects (e.g., bees and ants).

Myristic acid in amniotic fluid produces appetitive responses in human newborns.

Background: A mixture of eight fatty acids (lauric acid, myristic acid, palmitic acid, palmitoleic acid, stearic acid, oleic acid, elaidic acid, and linoleic acid) that are contained in human amniotic fluid, colostrum, and milk produces appetitive responses in newborns, suggesting the existence of a transition of sensorial cues that guide newborns to the maternal breast.

Objective: To explore the ability of each of these eight fatty acids individually to produce appetitive responses in newborns.

Methods: The study included 12 healthy human newborns<24h after birth.

Cognitive impairment in diabetes and poor glucose utilization in the intracellular neural milieu.

The main characteristic of diabetes is hyperglycemia. Depending on whether diabetes is type-1 or type-2, it is characterized by deficiencies in insulin secretion, insulin receptor sensitivity, hexokinase activity, and glucose transport. Current drug treatments are able to lower circulating glucose but do not address the problem of glucose utilization in the intracellular milieu, the consequence of which is tissue damage.

Progesterone modifies the responsivity of the amygdala-mPFC connection in male but not female Wistar rats.

Amygdala-medial prefrontal cortex (mPFC) connections partially regulate fear, anxiety, and the acquisition of conditioned fear. Progesterone exerts some effects on anxiety and fear. Currently unknown, however, are the actions of progesterone on the responsivity of amygdala-mPFC connections and possible sex differences.

Amniotic fluid or its fatty acids produce actions similar to diazepam on lateral septal neurons firing rate.

Human amniotic fluid (AF) contains eight fatty acids (FATs), and both produce anxiolytic-like effects in adult rats and appetitive responses in human newborns. The medial amygdala and lateral septal nucleus function are related to social behavior, but the action of AF or its FATs in this circuit is known. We obtained 267 single-unit extracellular recordings in Wistar rats treated with vehicle (1 mL, s.

Anterior olfactory organ removal produces anxiety-like behavior and increases spontaneous neuronal firing rate in basal amygdala.

Some chemical cues may produce signs of anxiety and fear mediated by amygdala nuclei, but unknown is the role of two anterior olfactory epithelial organs, the septal and vomeronasal organs (SO-VNOs). The effects of SO-VNO removal were explored in different groups of Wistar rats using two complementary approaches: (i) the assessment of neuronal firing rate in basal and medial amygdala nuclei and (ii) behavioral testing. Fourteen days after SO-VNO removal, spontaneous activity in basal and medial amygdala nuclei in one group was determined using single-unit extracellular recordings.

2-Heptanone increases the firing rate of the basal amygdala: role of anterior olfactory epithelial organs.

Wistar rats subjected to physical stress release a urine alarm pheromone (2-heptanone) that produces signs of anxiety and despair in receptor rats not subjected to physical stress. However, unknown are the effects of 2-heptanone on the firing rate of the basal amygdala, a structure that participates in the expression of fear, and the participation of anterior olfactory epithelial organs, namely the septal organ and vomeronasal organ (SO-VNO). We explored the effects of 2-heptanone applied near the nostrils on single-unit extracellular recordings from the basal amygdala in a sham-operated group and rats that underwent removal of the SO-VNO.

Amniotic fluid elicits appetitive responses in human newborns: fatty acids and appetitive responses.

In humans, maternal cues guide newborns to the maternal breast, and transitional cues may be present in maternal-fetal fluids. The aim of the present study was to determine the consistent presence of sensorial cues in three maternal-fetal fluids--amniotic fluid, colostrum, and milk--and test the ability of these cues to produce appetitive responses in newborns. In the analytical study, gas chromatography-mass spectrometry (GC-MS) detected eight fatty acids consistently present in the amniotic fluid, colostrum, and milk from 12 healthy volunteers, but we do not find a mammalian pheromone, identified in another mammalian species (rabbits), in another 30 volunteers.

Anxiolytic-like effects of human amniotic fluid and its fatty acids in Wistar rats.

Odors from amniotic fluid produce signs of calmness in mammals suggesting some anxiolytic-like properties. Experimental models, such as the defensive burying, elevated plus maze, and open field tests offer well-controlled approaches to the study of putative anxiolytic substances using rats. Using gas chromatography-mass spectrometry, we first identified eight fatty acids (lauric, myristic, palmitic, palmitoleic, stearic, oleic, elaidic, and linoleic acids) as consistently present in human amniotic fluid.

Testosterone reduces cumulative burying in female Wistar rats with minimal participation of estradiol.

Testosterone exerts anxiolytic effects, but the participation of its aromatase metabolic product estradiol is controversial. Therefore, we used the defensive burying paradigm in female Wistar rats to explore testosterone's (1.0 mg/rat, s.

Stressors can affect immobility time and response to imipramine in the rat forced swim test.

We subjected Wistar rats to the forced swim test (FST) to compare the effects of two doses of imipramine in physically stressed rats (P: unavoidable electric footshocks), emotionally stressed rats (E: odors), or non-stressed rats (C). Stress or control sessions lasted 35 days. Drug treatments began on day 21 and continued for the next 14 days.

Urine from stressed rats increases immobility in receptor rats forced to swim: role of 2-heptanone.

The present study was aimed to determine whether the urine from donor rats, which were physically stressed (UD-PS) by unavoidable electric footshocks, produces despair in receptor partner rats (RP) in the long-term. For each trial, an RP rat was placed during 10 min once per day for 21 days in a small non-movement-restricting cage impregnated with the urine collected from a UD-PS rat. Control rats, free of stimulation, maintained their locomotion and immobility scores at basal values throughout the 21-day test.

Allopregnanolone reduces immobility in the forced swimming test and increases the firing rate of lateral septal neurons through actions on the GABAA receptor in the rat.

Since allopregnanolone reduces the total time of immobility in rats submitted to the forced swimming test, we decided to explore whether this neuroactive steroid shares other antidepressant-like actions, such as increasing the neuronal firing rate in the lateral septal nucleus (LSN). In order to discard the influence of the oestrous cycle on immobility and on the firing rate of LSN neurons, all Wistar rats used in the study underwent ovariectomy before treatments. A group of rats received different doses of allopregnanolone (0.

A single session of emotional stress produces anxiety in Wistar rats.

The sensorial stimulation arising from a physically stressed (PS) subject may produce emotional stress in a witnessing partner (WP). Both members of the pair develop functional changes. We tested changes in locomotor activity (crossing) and in the defensive burying test in WP, and PS adult male Wistar rats having been submitted to a single 10 min session in a two-compartment cage.