 Dear students, in this module, we shall discuss in detail the neuropeptides, endorphins, and ancephalins. These substances are naturally occurring signaling molecules which are produced in the central nervous system. They act as analgesics, that is, they reduce the feeling of pain. They also induce euphoria during stress, that is, the feeling of betterment in stress. They also decrease urine output and reduce the rate of respiration. Central nervous system neurons have a lot of cells and receptors are present for endorphins or encephalins. These receptors bind the narcotic opiates, such as morphine, heroin, and opium. Because these molecules have similar structures and they mimic the endogenous endorphins and encephalins. So, they produce similar effects, that is, they reduce pain and also cause euphoria and change the emotional state of the person taking these opioids. Endorphins or encephalins receptors chunke external opiates ko bhi bind katte hain isli ye inke receptors ko opioid receptors katte hain. The exogenous opiates, that is, opium, and its derivatives produce extreme sense of plight. Brain ke andar, naturally bhi plightable activities ki vajah se endorphins ka level increase karta hain. Chunke ye external or internal opioids me ek similarity pae jati hain isli ye naturally produced endorphins ko hum endogenous opioids katte hain. Or opium aur uske derivatives ko exogenous opioids katte hain. Now, what is the basis of analgesic action of opioids? The opioids block the release of neurotransmitters from the nerve endings that are involved in the perception of pain. When these opioid molecules bind to the receptors, they also produce an intense feeling of plight. Yehi wo waja hain ke opiates ka bator narcotic drug used jo hain, ye popular hua. However, it has a side effect that ek persan jo continuously aisi doainyaan ya aisi drugs leta hain, to uske neti jaye main body ke andar, ya nervous system ke andar, compensatory changes produce hoti hain. Neuronal metabolism change hona shro ho jaati hain. So the removal of these opioids produces such changes in the system that they cannot be balanced without further dose of such drugs. Is ter hai ki jo metabolikali induced dependence hoti hain usse addiction ka hain jaata hain. Dear students, now we shall discuss the role of nellozone on opioid receptors. Nellozone is a drug that also binds to the opioid receptors in the sentinel nervous system, but it is, it acts as a competitive blocker of opioid receptors. Yehi jab yeh attach ho jaati hain receptor ka saath to uske baad yeh detach nahi hoti. It antagonizes narcotic effect of opiates. Then yeh jab yeh attach ho jaati hain, to receptor activate nahi hota, yehi jo cascade of enzyme reactions hain wo start nahi hoti. Isli yeh yeh opiates ko act karne se rohk leti hain, target cells ke upar unka action nahi hota. Nellozone ki yeh jo antagonistic properties hain, inko boh zyada used kiya hain opiod receptors ki detailed study meh aur unke mechanism of action ko understand karne meh yeh drug boh zyada helpful saabat hui hain.