LSD decreases in brain:

Correct Answer: A

Rationale: The correct answer is A: 5-HT2 receptor densities. LSD primarily acts on serotonin receptors, particularly the 5-HT2 receptors. When LSD binds to these receptors, it leads to a decrease in their densities in the brain. This is supported by research showing that LSD's hallucinogenic effects are mediated through its interaction with serotonin receptors. Choices B, C, and D are incorrect because LSD does not primarily target GABA, adrenergic, or dopamine receptors, so it would not lead to a decrease in their densities in the brain.

Correct Answer: B

Rationale: The correct answer is B: Vitamin B12. Pernicious anemia is caused by a deficiency of Vitamin B12, which is essential for the production of red blood cells. Without enough Vitamin B12, the body cannot make sufficient healthy red blood cells, leading to anemia. Erythropoietin (choice A) is a hormone that stimulates red blood cell production but is not directly related to pernicious anemia. Iron (choice C) deficiency leads to iron-deficiency anemia, not pernicious anemia. Vitamin B6 (choice D) deficiency can cause a different type of anemia but not pernicious anemia specifically.

Correct Answer: A

Rationale: Verapamil is a calcium channel blocker that can worsen heart failure symptoms by reducing heart contractility. Digoxin, dobutamine, and dopamine are commonly used to treat severe congestive heart failure by improving heart function. Verapamil is not recommended for heart failure management due to its negative inotropic effects.

Correct Answer: A

Rationale: Rationale: A: Incorrect. Bradycardic agents like Falipamil and Alinidine primarily act on cardiac tissue to decrease heart rate. They do not directly stimulate nerve endings to cause reflex and vascular dilative actions. B: Correct. The main effect of bradycardic drugs is to decrease heart rate without significant changes in arterial pressure. C: Correct. Bradycardic agents reduce oxygen demand on the heart which can be protective, especially in conditions like angina pectoris. D: Correct. Specific bradycardic agents are indeed used in the management of cardiovascular disorders like sinus tachyarrhythmias and angina pectoris.

Correct Answer: A

Rationale: Rationale: 1. Aminalon and Picamilon are GABA derivatives known to influence blood flow in the brain by enhancing cerebral circulation. 2. GABA derivatives like Aminalon and Picamilon act as vasodilators, improving blood flow without affecting blood pressure. 3. Nimodipine and Cinnarizine are calcium channel blockers that mainly act on vascular smooth muscle, not directly related to GABA. 4. Heparin and Warfarin are anticoagulants used to prevent blood clots, not directly affecting blood flow in the brain. 5. Vinpocetine and Nicergoline are vasodilators that enhance cerebral blood flow, but they are not derivatives of GABA.