• Central Neurotransmission of Acetylcholine (ACh):
• In the central nervous system, acetylcholine acting on muscarinic receptors ($M_1$ subtype) produces slow, prolonged excitatory postsynaptic potentials (EPSPs).
• The biochemical mechanism involves $G_q$-protein activation, which closes voltage-gated potassium channels (the M-current / $I_M$), causing a decrease in potassium conductance ($g_{K^+}$).
• Decreased outward $K^+$ efflux leads to membrane depolarization and sustained neuronal excitation.
• (GABA and Glycine increase chloride conductance; Dopamine acts through D1/D2 GPCRs).
• nalysis:
• (Acetylcholine): Correct.

Correct option: (4) Acetylcholine

• Evaluation of Antrycide Pro-Salt in Trypanosomiasis (Surra):
• Assertion (A): Antrycide pro salt is used for the therapy and prophylaxis of trypanosomiasis.
• True. Antrycide Pro-salt is widely employed in livestock for both immediate clinical treatment and extended chemoprophylaxis against Trypanosoma evansi.
• Reason (R): Initial short and rapid protection from trypanosomiasis is offered by Quinapyramine chloride, followed by prophylactic effect by Quinapyramine sulfate later.
• False (Inverted): Antrycide Pro-salt is a combination of two salts:

• Quinapyramine sulfate (soluble): Rapidly absorbed, providing immediate curative therapeutic action.
• Quinapyramine chloride (insoluble): Precipitates at the injection site and is slowly absorbed over months, providing long-term prophylaxis.
  • The statement in Reason reverses these roles.

• nalysis:
• ((A) is true but (R) is false): Correct.

• Robenidine in Poultry Coccidiosis:
• Robenidine hydrochloride: A synthetic guanidine derivative that acts as a coccidiostat by inhibiting ATP synthesis in first- and second-generation schizonts (acting on the 2nd day of the Eimeria life cycle).
• Meat Taint Risk:
• Robenidine residues deposit in broiler muscle and adipose tissues, imparting a sharp, unpleasant chemical/medicinal taste and odor to the cooked poultry meat.
• Statutory regulations mandate a strict minimum 5-day withdrawal period prior to slaughter to clear tissue residues.
• nalysis:
• (Robenidine): Correct.

Correct option: (4) Robenidine