Explain with examples drug agonism and antagonism in animals.

Drug agonism and antagonism refer to the effects of drugs on specific receptors in the body. Agonism occurs when a drug binds to a receptor and activates it, leading to a biological response. Antagonism, on the other hand, occurs when a drug binds to a receptor but does not activate it, blocking the receptor from being activated by other substances.

Examples of drug agonism in animals include:

1. Morphine is an agonist for opioid receptors in the brain, leading to pain relief and a feeling of euphoria in animals.

2. Beta-adrenergic agonists like albuterol bind to beta-adrenergic receptors in the lungs, causing relaxation of smooth muscle and bronchodilation in animals with asthma.

Examples of drug antagonism in animals include:

1. Naloxone is an antagonist for opioid receptors in the brain, blocking the effects of opioids and reversing their effects in animals experiencing an overdose.

2. Propranolol is a beta-adrenergic antagonist that blocks the effects of adrenaline on beta-adrenergic receptors, leading to a decrease in heart rate and blood pressure in animals with hypertension.