Biochemistry of Depression

Imipramine is a tricyclic antidepressant (TCA) that works by inhibiting the reuptake of serotonin and norepinephrine in the synapse.

5-HT2A receptors are a type of serotonin receptor found in the brain. They play a role in mood regulation and other brain functions.

Imipramine can increase serotonin levels in the synapse, even if they are initially low.

If serotonin levels are low in depressed patients, the 5-HT2A postsynaptic receptors in the synapse can become hypersensitive.

Imipramine inhibits the reuptake of monoamines like serotonin and norepinephrine.

Inhibiting reuptake leads to higher concentrations of monoamines in the synapse, thus increasing the chance for chemical transmission.

SSRIs (selective serotonin reuptake inhibitors) are a class of antidepressants that specifically target serotonin.

A type of antidepressant medication that works by inhibiting the enzyme Monoamine Oxidase (MAO).

In depressed patients, there may be a quick reuptake of serotonin because of low levels and hypersensitive receptors, making it hard for the neurotransmitter to transmit signals effectively.

The enzyme that breaks down monoamines (neurotransmitters like serotonin and norepinephrine) in the synapse.

The space between two neurons where communication happens through neurotransmitters.

Neurotransmitters that are involved in mood regulation, such as serotonin and norepinephrine.

MAOIs prevent the breakdown of monoamines by inhibiting the action of MAO. This allows for higher levels of monoamines in the synapse.

Increases in serotonin and norepinephrine levels lead to improved mood and reduced symptoms of depression.

The time it takes for MAOIs to start showing their effects.

A class of antidepressant medications that affect neurotransmitters like serotonin and norepinephrine.

A neurotransmitter associated with pleasure, motivation, and reward. It plays a role in movement, attention, and learning. Low levels of dopamine are linked to depression.

A neurotransmitter that regulates mood, sleep, appetite, and social behavior. Serotonin helps to stabilize our emotions and promote feelings of well-being. Low levels can contribute to depression.

A neurotransmitter that plays a crucial role in alertness, focus, energy, and responding to stress. It's also involved in fight-or-flight responses and memory.

A complex communication system in the body that regulates stress response. It involves the hypothalamus, pituitary gland, and adrenal glands, which work together to release hormones like cortisol.

The study of how drugs affect the body and its functions, specifically focusing on how medications are used to treat mental health disorders like depression.

A class of antidepressants that primarily work by inhibiting the reuptake of serotonin in the brain, leading to increased serotonin levels in the synaptic cleft.

A class of antidepressants that inhibit the reuptake of both serotonin and norepinephrine, boosting their levels in the brain.

A class of antidepressants that primarily work by inhibiting the reuptake of norepinephrine, leading to increased norepinephrine levels in the synaptic cleft.

A group of antidepressants that have a broader range of actions and don't fit neatly into other categories. Examples include mianserin and trazodone.

A state of excessive serotonin activity in the body, potentially caused by interactions of medications or drug abuse. Symptoms can include agitation, confusion, and muscle rigidity.

A decrease in the sensitivity of a specific type of receptor over time due to continuous exposure to a drug or neurotransmitter.

A neurotransmitter involved in arousal, attention, and alertness.

The process by which a neurotransmitter is reabsorbed back into the presynaptic neuron after being released into the synaptic cleft.

A protein responsible for transporting serotonin back into the presynaptic neuron, thereby reducing synaptic serotonin levels.

The ability of an antidepressant to effectively treat depressive symptoms.

The tendency for an antidepressant to be effective in a population with a specific condition, such as depression.

The ability of a medication to be taken with other drugs or food without significant interactions or side effects.

Depleting the body's tryptophan levels can worsen mood in people who have recovered from depression and are taking SSRIs. This is because tryptophan is a precursor for serotonin, an important neurotransmitter involved in mood regulation.

5-HT1A autoreceptors are located on the presynaptic neuron and regulate the release of serotonin. When activated, they inhibit the release of serotonin, leading to reduced levels of serotonin in the synapse.

In major depressive disorder (MDD), there is evidence of hypersensitivity of 5-HT1A autoreceptors, leading to a rapid and strong inhibition of serotonin release. This contributes to lower serotonin levels in the brain.

Antidepressants like SSRIs work by slowing down the process of 5-HT1A autoreceptor activation. This allows for more serotonin to be released in the synapse, ultimately improving mood.

Medications like mianserin and trazodone are examples of antidepressants that act as antagonists of 5-HT2 and alpha receptors. They can enhance the effects of SSRIs by reducing the inhibition of serotonin release.

Postmortem studies have revealed a reduced density of layer III neurons in the dorsolateral prefrontal cortex (DLPFC) of individuals with depression. These neurons play a role in higher cognitive functions.

The hippocampus, a brain structure involved in memory and emotion regulation, is found to have reduced volume in individuals with recurrent depression. This suggests a potential link between hippocampal dysfunction and depressive episodes.

The amygdala, responsible for processing fear and emotions, shows increased connectivity and heightened activity in individuals with depression. This heightened activation can contribute to feelings of anxiety and fear.

Early life stress, such as abuse or neglect, can lead to persistent increases in the release of corticotrophin-releasing hormone (CRH). This can trigger a dysregulation of the hypothalamic-pituitary-adrenal (HPA) axis, increasing vulnerability to depression.

Stressful experiences can cause damage to the hippocampus, leading to a disruption in the brain's ability to regulate emotions. This hippocampal damage has been implicated as a potential pathway to depression.

The a2 receptor, located on presynaptic neurons, acts as an autoreceptor for noradrenaline. When activated, it inhibits the release of noradrenaline, ultimately reducing its levels in the synapse.

Similar to the explanation for serotonin, altered activity of the a2 receptor is also proposed to play a role in depression. Altered receptor activity can affect noradrenaline levels, potentially contributing to depressive symptoms.

Reserpine is a blood pressure medication that works by depleting neuronal stores of both noradrenaline and serotonin. This depletion can lead to depressive symptoms due to the reduced availability of these crucial neurotransmitters.

Decreased levels of the serotonin metabolite, 5-HIAA, and the noradrenaline metabolite, MHPG, have been observed in the cerebrospinal fluid (CSF) of depressed individuals. These findings suggest altered metabolism of these neurotransmitters in depression.

A protein crucial for neuronal survival, growth, and differentiation in the brain. It's like a growth factor for neurons, helping them stay healthy and communicate effectively.

A class of proteins that regulate the survival, growth, and differentiation of neurons. They act as growth factors for the nervous system, like a team of helpers for neurons.

A crucial neurotrophin that plays a critical role in neuronal survival, growth, and plasticity, enabling learning and memory. It's like a key player in brain development and function.

The process by which neurons adapt and change their structure and function in response to experience. It's like a brain's way of learning and growing.

The major stress hormone in the body. It's like a firefighter, responding to stress by helping the body cope.

The primary receptor for cortisol, situated in various cells throughout the body. It's like a lock that cortisol binds to, triggering various responses within cells.

A phenomenon observed in some individuals with depression, where the body's response to cortisol is diminished. It's like a phone that's not receiving signals properly, resulting in a reduced effect.

A system within the body responsible for regulating stress response. It's like a command center, orchestrating the body's reaction to stress.

A chronic mood disorder marked by persistent feelings of sadness, loss of interest, fatigue, and other symptoms. It's like a dark cloud following someone around, impacting their mood and wellbeing.

A theory proposing that depression arises from a dysfunction in the levels or activity of certain neurotransmitters, particularly serotonin and norepinephrine, in the brain. It's like a chemical imbalance in the brain, affecting mood and behavior.

A type of receptor involved in the regulation of mood, sleep, appetite, among other functions. It's like a gatekeeper for certain chemical messages in the brain.

A receptor involved in the regulation of mood, attention, and other brain functions. It's like a 'target' for norepinephrine, influencing alertness, focus, and mood.

The therapeutic effect of antidepressants, specifically those targeting norepinephrine, is thought to involve a process that involves the desensitization of certain receptors, mainly the alpha-2 receptors followed by beta receptors. It's like a fine-tuning process involving receptors, resulting in mood improvements.