Relaxin family peptide receptors Rxfp1 and Rxfp2: mapping of the mRNA and protein distribution in the reproductive tract of the male rat

Background  

Relaxin is the endogenous ligand of the G-protein coupled receptor RXFP1, previously known as LGR7. In humans relaxin can also activate, but with lower affinity, the closely related receptor for the insulin-like peptide from Leydig cells, RXFP2, previously known as LGR8. The lack of relaxin impairs male fertility but the precise distribution and the function of relaxin receptors in the male reproductive tract is not known. We investigated the distribution of Rxfp1 and Rxfp2 in the reproductive tract of the male rat and the function of relaxin in the vas deferens, a tissue with high expression of both receptors.     

Augmentation by naloxone of efflux of LRF from superfused medial basal hypothalamus

The effects of naloxone and β-endorphin (β-EP) on the efflux of luteinizing hormone releasing factor (LRF) from superfused rat medial basal hypothalamus (MBH) were determined. After an equilibration period of 2.5 hrs with Medium 199 at 37°C 0.5 ml fractions were collected. Infusion of medium containing 150 mM KCl for 10 min produced a prompt 4-fold rise in LR$\text{F}$ efflux. Injection of naloxone, but not medium alone, into the system significantly increased the effluent concentration of LRF from female (N = 6) MBH's by 177% (P < 0.01) and from male (N = 5) MBH's by 108% (P < 0.05). Administration of β-EP did not significantly alter LRF efflux. However, β-EP did nullify the LRF-stimulating effect of naloxone, when an equimolar mixture of β-EP and naloxone was injected. We conclude that naloxone-sensitive opiate receptors exert a tonic inhibitory effect on tuberoinfundibular LRF neurons. This action does not require the intermediation of brain centers outside the MBH.     

Cyclic melanotropins. Part VII: Modified ring structures--synthesis and biological activity

The highly potent cyclic analogue of alpha-MSH, Ac-[Cys4,Cys10]-alpha-MSH4-13-NH2, was structurally modified in position 4. Four analogues were prepared and their biological activities in the in vitro frog and lizard skin bioassays were determined. It was shown that removing the terminal acetylamino group to give [Mpa4,Cys10]-alpha-MSH4-13-NH2 resulted in little change in the biological activity, but a change in the stereochemistry of cysteine in position 4 to give Ac-[D-Cys4,Cys10[-alpha-MSH4-a3-NH2 led to a small decrease of activity in both bioassays. Decreasing the size of the intramolecular ring by removing one methylene group to give [Maa2,Cys10]-alpha-MSH4-13-NH2, resulted in an analogue with lower activities in both assays (about 3 times in the lizard and 500 times in the frog), and increasing the size of the righ by methylene group to give Ac-[Hcy4,Cys10]-alpha-MSH4-13-NH2 led to much lower activities in the lizard system and similar effects were seen upon decreasing the ring size in the frog skin assay.     

Don't forget the children.

Serious illness or hospitalization of a parent is potentially destructive to the mental health of the child. Stress is caused by both the separation and the illness itself. If the physician does not ensure that the situation is explained to the child, it is likely the child will be confused and frightened and any attempts at clarification will be blocked in the attendant family dysfunction. The general principles of prevention are to share the facts of the situation with the child and to allow him his natural and varied reactions. The family interview is useful in clearing up misunderstandings, sharing feelings and working out family roles.     

Adolescent smokers seen in general practice: health,lifestyle, physical measurements,and response to antismoking advice.

OBJECTIVE--To compare physical, lifestyle, and health characteristics of adolescent smokers and non-smokers and their initial response to anti-smoking counselling. DESIGN--Adolescents aged 13, 15, and 17 years were identified from age-sex registers and invited by letter for a general practice health check. SETTING--Three general practices in the MRC general practice research framework. MAIN OUTCOME MEASURES--Blood pressure, body mass index, saliva cotinine concentration, peak flow rate, alcohol consumption, exercise, duration of sleep, and stated persistent health problems. RESULTS--73% of the adolescents (491) attended for the health check. A total of 68 (14%) were regular smokers. By age 17 those who smoked regularly had a significantly lower systolic blood pressure than those who had never smoked regularly (by 6 mm Hg; p = 0.025) despite a significantly higher body mass index (by 1.5; p <0.001) [corrected]. Cotinine concentrations increased with smoking exposure, from 0.7 ng/ml when no family member smoked to 155 ng/ml in active smokers of six or more cigarettes a week. Significantly more regular smokers than never regular smokers drank greater than or equal to 8 g alcohol a day (chi 2 = 15.2 adjusted for age and sex p less than 0.001); regular smokers exercised less (1.0 hrs/week in boys and 0.8 hrs/week in girls v 3.4 hrs/week in boys and 2.2 hrs/week in girls; p less than 0.001) and slept less (8.0 hrs/night v 8.5 hrs/night at age 17; p less than 0.005). Persistent health problems, mostly asthma or allergic symptoms, were reported by 25% (17/68) of the smokers and 16% (60/381) of the non-smokers. Of the smokers given counselling, 60% (26/43) made an agreement with the practice doctor or nurse to give up smoking. CONCLUSION--General practice is an appropriate setting for adolescents to receive advice on healthy lifestyle, which should not focus solely on smoking.     

Comparative biological activities of potent analogues of alpha-melanotropin. Effect of nonaromatic and para substituted aromatic amino acids at position 7

Several alpha-melanotropin (alpha-MSH) analogues with para substituted aromatic and nonaromatic amino acids in the 7-position of the hormone were prepared and their melanotropic activities determined in the frog (Rana pipiens) and lizard (Anolis carolinensis) skin bioassays. D and L-Phe(p-NO2), D- and L-Tyr, D- and L-Ala, and Gly were substituted in the 7-position. The use of substituted D or L-aromatic amino acids in the 7th position of the central Ac-[Nle4]-alpha-MSH4-11-NH2 fragment resulted in a loss in potency relative to the corresponding phenylalanine-containing analogue. The loss in potency cannot be due entirely to steric hindrance at the melanophore receptor, since nonaromatic amino acids substituted in the 7th position of this octapeptide fragment also generally led to a loss in biological activity. We reported previously that replacement of phenylalanine-7 by its D enantiomer led to a marked increase in potency in each fragment analogue tested. Analogues containing other D amino acids in the 7th position also were more potent than their L amino acid-containing analogues with one exception: Ac-[Nle4, Ala7]-alpha-MSH4-11-NH2 was more potent than Ac-[Nle4, D-Ala7]-alpha-MSH4-11-NH2 in the frog skin bioassay. Replacement of phenylalanine-7 by glycine resulted in a large decrease in potency in both bioassays, illustrating the importance of the side chain group, in this position of alpha-MSH, to biological potency of the hormone.     

Comparison of calibration methods for respiratory inductive plethysmography in infants

In infants under the age of 6 mo respiratory inductive plethysmograph (RIP)-calculated tidal volumes (VT) were compared with simultaneously measured volumes using a pneumotachograph (PNT) to 1) assess whether using multiple points (MP) along the inspiratory profile of a breath is superior to using only VT when calculating volume-motion (VM) coefficients, 2) verify the assumption of independent contributions of the abdomen and rib cage to VT, which was accomplished by extending the normal RIP model to include a term representing interaction between these two compartments, and 3) investigate whether VM coefficients are sleep-state dependent. Neither use of multiple points nor inclusion of the interacting term improved the performance of the RIP over that observed using a simple two-compartment model with VT measurements. However, VM coefficients obtained during quiet sleep (QS) were not reliable when used during rapid-eye-movement (REM) sleep, suggesting that coefficients obtained during one sleep state may not be applicable to another state where there is a substantial change in the relative abdominal/rib cage contributions to VT.