<prompt> Increasing the concentration of norepinephrine in adrenergic synapses leads toActivation of tyrosine hydroxylaseActivation of dopa decarboxylaseIncreased release of norepinephrineActivation of presynaptic Gi C coupled receptors  <response>: Classification:- Adrenergic receptors are classified into two types a and b. The a receptors were demonstrated to be present prejunctionally as well. To differentiate these release inhibitory prejunctional a receptors, a subdivision into a1 and a2 was suggested. b receptors were fuher subdivided into b1, b2, beta 3subtypes. Alpha2 receptor is located prejunctionally and inhibits the release of neurotransmitter. Ref:- kd tripathi; pg num:-126,127 