The aim of this study is to gain insight into the time during the life history of a retinal neuron that it becomes committed to a particular phenotype. At this point, it is not possible to identify the time of commitment, but the time that differentiation begins can be identified. Bromodeoxyuridine labeling coupled with immunohistochemistry with a ganglion cell-specific antibody was used to fix the time of the beginning of ganglion cell differentiation relative to the time of mitosis in the developing chick retina. It was found that ganglion cells can begin to differentiate in less than 15 min after the end of mitosis. This suggests that the retinal ganglion cell fate may be determined before or during mitosis.

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This is the first study to examine how both structural and functional components of individuals’ social networks may moderate the association between biological sex and experimental pain sensitivity. One hundred and fifty-two healthy adults (mean age = 22yrs., 53% males) were measured for cold pressor task (CPT) pain sensitivity (i.e., intensity ratings) and core aspects of social networks (e.g., proportion of friends vs. family, affection, affirmation, and aid). Results showed consistent sex differences in how social network structures and intimate relationship functioning modulated pain sensitivity. Females showed higher pain sensitivity when their social networks consisted of a higher proportion of intimate types of relationship partners (e.g., kin vs. non kin), when they had known their network partners for a longer period of time, and when they reported higher levels of logistical support from their significant other (e.g., romantic partner). Conversely, males showed distinct patterns in the opposite direction, including an association between higher levels of logistical support from one’s significant other and lower CPT pain intensity. These findings show for the first time that the direction of sex differences in exogenous pain sensitivity is likely dependent on fundamental components of the individual’s social environment. The utility of a social-signaling perspective of pain behaviors for examining, comparing, and interpreting individual and group differences in experimental and clinical pain reports is discussed.

In this report we studied coupling of M₂ and M₄ muscarinic acetylcholine receptors to activation of endothelial nitric oxide synthase (eNOS). Chinese hamster ovary cells that co-express the individual receptor subtypes and eNOS in a stable fashion were used as a model. Activation of eNOS was assayed by measuring increasing levels of cyclic GMP in admixed cells that contain guanylate cyclase. Activation of both M₂ or M₄ muscarinic receptors resulted in marked activation of eNOS, in a time- and concentration-dependent manner. The time course of the response exhibited a transient peak, followed by a sustained lower plateau. While the sustained phase was dependent on influx of extracellular calcium, the transient response showed dependency on both mobilization of intracellular calcium and extracellular influx.

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